₦airaland Forum

ebner70:
Just started noticing this check sign and VSC sign on my rx300, any idea of the meanings ND possible solution

You have a MIL - Malfunction Indicator Light on.

Why do you have a malfunction indicator light on?

The vehicle's PCM or ECU has detected either an emissions fault or a drivability fault.

To determine what sort of fault has been detected you need to communicate with the PCM or ECU, but do you know how to speak OBD II which is the only language it understands? NO!

To communicate with the PCM or ECU in the language it understand, you need a Scan Tool

The Scan Tool speaks the language of the PCM or ECU

The Scan Tool will then translate that language into English which you speak and understand in the form of DTCs

Actually as been pointed by others on this thread you have two lights indicating your vehicle is not operating as it was designed

If you have difficulty understanding any of the terms I have used, then please visit this thread https://www.nairaland.com/3661728/on-board-diagnostics-obd-ii-questions

If you still have questions, throw them at me, and I will respond when I can

If I was helpful, you should bookmark that thread and visit it often

Dbkk:
Did you buy this vehicle brand new or is it new to you? Bought it Naija used

What is it's mileage? About 141k

How long have you had this problem? I dunno, I don't usually check fuel trim

Was any repair made before you had this problem? None by me, & no maintenance history base on naija used

Or is the MIL on but no drivability issues/complaints? No drivability issue

Can I have your Freeze Frame Data?
Current Parameter Display information?

Seen.

To be sure that we are absolutely on the same page, please read my last post on this page https://www.nairaland.com/3661728/on-board-diagnostics-obd-ii-questions

I will be back with a detailed response based on the data that you have provided.

What is OBD II?

The second iteration of the OBD standard, i.e., An enhanced iteration of the OBD standard (capability-wise and standardization-wise)

Before OBD II, different manufacturer had different connectors, different pinouts, different electrical signaling protocols, and different messaging formats, non-standard DTCs.

In other words, you had purchase a different scan tool for every make of vehicle - imagine the cost implications for technicians and their shops in the days prior to OBD II

OBD II is an enhanced diagnostic monitoring tool that is integrated into vehicle PCM or ECU

OBD II allows your PCM or ECU to provide real-time data on its operations

Your PCM or ECU can generate a standardized series of diagnostic trouble codes (DTCs) which helps tremendously in the detection and remediation of faults in the vehicle

OBD II started life around 1994.

OBD II became mandatory in 1996 for all cars meant for the American market

It is basically an emissions standard and was initially designed for the reporting of vehicle emission status, but manufacturers latched onto the standard making it the de facto diagnosis and reprogramming protocol

If your vehicle's emission levels are greater than 1.5 times the originally certified emissions level, it with output a diagnostic trouble code (DTC).

The OBD standard was driven largely by the California Air Resources Board (CARB)'s mission of improving the quality of the environment - hence the statement that it was basically an emissions standard.

OBD II was built from the ground up sense failures in vehicle emissions control systems that would result in increased emission (read that to mean) pollution levels.

These failures could be electrical, chemical or mechanical.

With OBD II, if all systems (electrical, mechanical) except the catalytic converter are functioning perfectly, then there is a problem. A chemical failure. What chemical failure? A catalytic converter failure who is not doing its work.


https://www.youtube.com/watch?v=DXchXMVteyk

And what is the work of a catalytic converter? To chemically purify the air that passes through it! This failure is enough to cause the PCM/ECU to output a code.

This was not the case with OBD I, a chemical failure would not lead to a MIL!

The take-home lesson - OBD I brought drivability to the fore. OBD II brings emission (pollution) levels to the fore.

OBD II will however also output codes related to drivability - but that is not the primary reason why it is monitoring vehicle systems!



What this means is that irrespective of what you think or your friends and neighbors think, if your car was built to this standard, you are driving a modern car!

Brother and Sister, if your technician does not understand this language, you are in big trouble.

If your vehicle is a post 1996 vehicle. If your technician says don’t worry about the MIL, you are in even bigger trouble, because the car is telling you I got an issue, I need a checkup and you are ignoring it.

If your MIL was deleted, by your or the person who sold the car to you, then you know who your enemy is, how you intend to deal with him, well, I’ll leave that to you!


Got questions on OBD II? We will try to answer them in a down-to-earth manner so that anyone can understand!

What is On-board diagnostics (OBD)?


Wikipedia defines it as “an automotive term referring to a vehicle's self-diagnostic and reporting capability. OBD systems give the vehicle owner or repair technician access to the status of the various vehicle subsystems. The amount of diagnostic information available via OBD has varied widely since its introduction in the early 1980s versions of on-board vehicle computers. Early versions of OBD would simply illuminate a malfunction indicator light or "idiot light" if a problem was detected but would not provide any information as to the nature of the problem. Modern OBD implementations use a standardized digital communications port to provide real-time data in addition to a standardized series of diagnostic trouble codes, or DTCs, which allow one to rapidly identify and remedy malfunctions within the vehicle.”

Source: https://en.wikipedia.org/wiki/On-board_diagnostics

Dbkk:
Good days gurus, please what are the causes of negative fuel trim? On but short term & long term, from my little research online, means the engine is running rich meaning higher fuel consumption, the car is Honda accord 2006 i4, the only MIL code on is catalyst code P0420
Cc Gazzu.zz Nu.rey Hon.musa Mayor.2013 King.reign Pi.yke Egun.Mogaji

I will address your question soon.

This is an OBD II issue.

I think is is wrong to call that MIL code just.

OBD II considers emissions issues more important than drivability issues.

The catalytic converter is a major part of your vehicle's emission control system.

Expect an in-depth explanation of the issues later.

To help me treat the issues as they affect your vehicle in particular and not just this code in general

Did you buy this vehicle brand new or is it new to you?
What is it's mileage?
How long have you had this problem?
Was any repair made before you had this problem?
Do you have any drivability issues?
Or is the MIL on but no drivability issues/complaints?
Can I have your Freeze Frame Data?
Current Parameter Display information?

If I can have this information, I will personalize the response.

I can see you have your own OBD II Scanner! That's a big plus!!


And subscribe to this thread https://www.nairaland.com/3661728/on-board-diagnostics-obd-ii-questions


---------
MODIFIED
---------

Here is what additional information I need to know:

What is the current status of the MIL
1. Do you have no driveability complaint along with the MIL?
2. Do you have driveability complaint(s) along with the MIL? If yes, kindly explain.

Have you ever erased the DTC? Did it come back after that?


Freeze Frame Data required includes:
Fuel System Status (whether Open Loop or Closed Loop)
Calculated Load in Percentage
Short Term Fuel Trim Bank 1 in Percentage
Short Term Fuel Trim Bank 2 in Percentage
Long Term Fuel Trim Bank 1 in Percentage
Long Term Fuel Trim Bank 1 in Percentage
Engine Speed in RPM
Vehicle Speed in MPH or km/h
Engine Coolant Temperature in degrees
If a single-cylinder misfire is detected, indicate cylinder(s)

Current Parameter Display Information required includes:


Fuel System Status (whether Open Loop or Closed Loop)
Calculated Load in Percentage
Short Term Fuel Trim Bank 1 in Percentage
Short Term Fuel Trim Bank 2 in Percentage
Long Term Fuel Trim Bank 1 in Percentage
Long Term Fuel Trim Bank 1 in Percentage
Engine Speed in RPM
Vehicle Speed in MPH or km/h
Engine Coolant Temperature in degrees

We cannot just look at fuel trims in isolation because that is not how the ECU does, it looks at multiple sources of data and then uses them to decide one way or the other, so to solve a problem properly, we have think the way the OBD II system thinks, sort of peek into its mind!

Title: Advanced On-Board Diagnostics (OBD II) Strategies

Purpose: Familiarize participants with everything they need to know to diagnose post OBD II vehicles intelligently and professionally

Instructional Method:
1. Lectures
2. Discussions
3. Hands-on Practice
4. QnA sessions on Nairaland

Training Environment:
1. Classroom
2. Service Bay
3. ELearning (to reinforce concepts taught in 1 and 2 if you desire)

Materials Needed:
1. Pen
2. Pencil
3. Paper
4. Computer
5. Phone
6. Tablet

Training Aids:
1. PowerPoint Presentations
2. Videos
3. Computers
4. Handouts
5. Simulations
6. A variety of tech tools including but not limited to OBD Scanner and DMM (more advanced tools will be required later)
7. posts on Nairaland

Over the course of the following 7 days, the promise made on at 11.51pm on November 16, 2016 will be fulfilled.

How important to drivability is a well-maintained ignition system?


What a vehicle owner needs to know about ignition systems?

In the meantime, if you have any questions on automobile Electricity and Electronics, feel free to post and be assured you will receive a response as soon as possible

kedra:
Well done AutoElectNG..pls how do I resolve P1520 error code on a 2002 toyota camry

Your code is P1520.

This code for your vehicle and model stands for - Stop Lamp Switch Signal Malfunction - it is not a generic code, it is a Manufacturer specific code.

This is clearly an electrical problem. The problem signal is used by the vehicle computer to detect if you have depressed the brake pedal. It's second function is to control fuel cutoff which results in the vehicle computer lowering engine speed.

This code is coming up because the vehicle computer is not receiving or detecting the signal.

What could cause these state of affairs?

1.Faulty stop light switch

2. Stop light switch is not properly connected

3. Short in the harness for the stop light switch

There is no difference between what Toyota calls a stop light switch and what some other manufacturers call a brake light switch

This extract sourced from should enlighten you a bit more: https://www.yourmechanic.com/services/brake-light-switch-replacement

Brake Light Switch Replacement Service & Cost

What is the Brake Light Switch all about?

When driving, brake lights notify people behind you that you are slowing down or stopping. If your brake lights do not work, you are at risk for causing accidents.

The brake light switch is connected to the brake pedal of the car. When you step on the brake pedal, the brake lights turn on. If the switch is faulty, the brake lights will not work.

Keep in mind:

Although uncommon, sometimes the electrical wires connected to the switch break. In that case, the mechanic will need to replace the electrical connector.

A brake light switch failure can affect the operation of the shift interlock system and not allow the driver to shift from Park to Drive.

How it's done:


Inspect brake light switch, circuit, and fuses.

Remove and replace the brake light switch if not working.

Replace the fuse if it is blown.

Check operation of the brake lights.

Verify the vehicle can be shifted from Park to Drive.

Our recommendation:


The brake lights and brake switch should be inspected regularly as part of a major service.

What common symptoms indicate you may need to replace the Brake Light Switch?


Brake lights not working.

Not being able to shift out of Park.

How important is this service?


When you depress the brake pedal, the brake light switch sends a signal to your brake lights, and turns them on. Brake lights are an important safety feature (and a legal necessity), but they rely on the brake light switch to turn them on. Without a functioning brake light switch, there will be no communication between your brake pedal and your brake lights.

Since each manufacturer implements these standard vehicular components differently, a technician will need access to the vehicle wiring diagrams and troubleshooting routine to do a good job of fixing this issue for you. I provided generic instructions, and because those do not come free, it will definitely be at some cost to you.

Are you a handyman? You want to do it yourself or do you need professional help to get it done?

If there is anything that is not clear, feel free to drop a line...

critic007:
Hello Op
I have issues with my Opel vectra B, 1998 model. The speedometer and RPM just stopped working. Once I tried hitting the dashboard, it worked. Ever since then, its been at 0. What do I do? Thanks

Does it behave like this one?


https://www.youtube.com/watch?v=o8lOko3NpZs

We need wiring diagrams to do further and detailed diagnostics

castro:
Hello guys, I have been reading some of the posts on this section and I believe I should be able to get a solution for my vehicle. I parked the car for more than a year when I went for a post graduate and ever since I returned I have tried to kick-start the vehicle. Initially it woul start but after a few minutes, it would rev but and then go off. Now it doesn't kick-start at all. One mechanic told me its ignition problem while another said its the nozzles. Pls who can tell me what the problem is?

Which battery are you using to start this vehicle? The one stored for more than a year or a brand new one?

If it is the one stored for over a year, can you get it load tested? I did not say voltage testing, I said load tested.

If you cannot find a place to do load test of the old battery, then I suggest you replace the battery with new and if it still does not start, then we can go neck deep into proper starting system troubleshooting.

Is your charging system in order?

Get a competent electrician to go through the entire system.

Ensure that the charging system is ok, so we can concentrate on confirming if you have a starting system problem or something else?

arcbaba:
Well I bought the car recently Nigeria used, just noticed it 3days after buying it. It's a toyota Camry 1999 model pencil light. Spoke to an auto electrician he said it wud be difficult to diagnose since it does not happen all the time.

SECOND RESPONSE!


Your speedometer (part of the instrument cluster called combination picture in the diagram I have encouraged you to download and study below) receives input data from a Vehicle Speed Sensor.

This Vehicle Speed Sensor can be found on top of the bell housing ( Wikipedia defines it as the portion of your transmission that covers the flywheel and the torque converter) of your automatic transmission.

Reasons why you have problems with your speedometer include:
1. a failed Vehicle Speed Sensor;
2. bad wiring between the Vehicle Speed Sensor and the Instrument Cluster
3. a bad instrument cluster
4. bad wiring between the Instrument Cluster and the ECM
5. A bad Engine Control Module

The attached picture illustrates how the system works.

Credits for the picture: https://d3nevzfk7ii3be.cloudfront.net/igi/tLijsFcZx2rhnYyn

To do a good job of tracing the problem will require consulting the manufacturer wiring diagrams and comparing with what currently obtains on your vehicle.

The manufacturer also provides troubleshooting guides so tests can be run to trace the fault that is causing this state of affairs.

I hope this detailed response is of benefit to you.

arcbaba:
Well I bought the car recently Nigeria used, just noticed it 3days after buying it. It's a toyota Camry 1999 model pencil light. Spoke to an auto electrician he said it wud be difficult to diagnose since it does not happen all the time.

Sorry for the long period of absence.

Does this video indicate the problem that you are facing?


https://www.youtube.com/watch?v=JwTd9mOKvsY

arcbaba:
Hi, I have an issue with my speedometer, It does not work sometimes, I notice it happens more when the car is parked for long under the heat of the sun. sometimes it works for days without any issues, on some days it does not work at all but start working unexpectedly anytime. I really don't know what is wrong.

Specifications of the vehicle?
Make
Model
Trim

What work was done before this happened?

Or it just started all of a sudden?

Andy790:
well done sir....

am really interested in automobile electronics...

I wouldn't mind learning under you.

more like an apprentice or intern.

please give me your contact let's talk
thanks

Send me a PM via the nairaland messaging system or drop your email address

Does it make sense to buy a tokunbo ignition coil pack?

Yes and No!

Yes - if it is tested not using battery positive and negative terminals (as is commonly done in local auto markets) but with a DMM to confirm that its resistance matches manufacturer engineering tolerances (professional electricians always refer to wiring diagrams when troubleshooting or doing R&R i.e., Remove and Replace)

No - if it is bought on the false assumption that a tokunbo product is as good as new but with a shorter life span (so no need to test with a DMM but just with a battery's positive and negative terminals, so no need to consult manufacturer specifications as well as TSBs, so long as the physical appearance is identical, then all is good)

I'll elaborate in subsequent posts, and I will also try to explain in some measure of detail in plain language just how important to vehicular operation a well-maintained ignition system is.

Ideally, though, the customer is advised to replace a failed or sub-optimal ignition component with a brand new equivalent for best results

DO'S AND DON'TS

If your technician pulls off a plug wire or the coil's high voltage output wire to test for a spark, then sorry to say, he is either a quack or is uneducated as to the damage to the vehicle's sensitive electronic ecosystem he is causing and by extension your pocket!

He could get a serious electrical shock ( as low as 6,000 volts and as high as 12,000 to 40,000 and even 100,000 Volts is required to fire the spark plugs in most applications to jump the air gap of the spark plugs)

If such voltages do are not able to follow their natural path, they will follow unnatural paths, and they will leave a lot of sorrow and destruction in their wake!

He could end up converting your coil into a useless brick

In the end, you pay. He goes Scot-free

How's that for one more reason to pick and educated mechanic, over his uneducated counterpart

abussyaya:
Hi Autoelectng,

I ran into a bump today and there after my Car CD player stopped working but the Radio still works. I have also been unable to eject the CD that was playing after I ran into the bump. It's a Honda Accord 2006 model, Single CD, OEM.

It has shown CD Error a few times in the past though.[color=#006600][/color]

While waiting for your response, this problem will require physical inspection to resolve.

But here are some suggestions:

1.
https://www.youtube.com/watch?v=kwuUo5H-ko8

2. Search for this link at forum (.) edmunds (.) com "How to remove a stuck CD"

3. Search for this link "How to remove a stuck CD from a car player" at wikihow (.) com

4. Refer also to my response here: https://www.nairaland.com/3456276/automobile-electricity-electronics-question-answer#50928460 (and follow the procedure before this line of text: "If either method of rebooting the ECU fails to yield positive results, then you have five options:"

abussyaya:
Hi Autoelectng,

I ran into a bump today and there after my Car CD player stopped working but the Radio still works. I have also been unable to eject the CD that was playing after I ran into the bump. It's a Honda Accord 2006 model, Single CD, OEM.

It has shown CD Error a few times in the past though.

CD Player bad = CD Player not ejecting after bump hit
Radio OK

Did the CD Error show before the bump hit or after the bump hit?

consultancy:
@AutoElect i must really commend you for takin out time to respond to me. i should say this, the car just went into a pothole at top speed with the driver side tires only, and the airbag came out. no form of damage was done to the car tires, or any parts of the car exterior. so i guess the srs module should still be intact. i already arranged to take it for a scan when i arrive lagos anyway

Your welcome.

Keep me posted.

Particularly interested in a Honda HDS scan results from your ride when you get back to base as to the state of the airbag sub-system

consultancy:
yes just the airbag, nothing else was replaced

That seems to be where the problem comes from.

You need to replace the side curtain airbag + SRS module (new preferred but some people poach it from the scrapyard which is not recommended) + a side impact sensor (new preferred but some people poach it from the scrapyard which is not recommended)

And maybe also programming so the unit can recognize the newly installed modules - I said may because I have not consulted the Service Manual for your vehicle in particular but for vehicles from the same manufacturer, and the procedures differ a bit from manufacturer to manufacturer and vehicle to vehicle.

The reason is that the the SRS module stores crash data every time the airbag deploys - hence the need to either reset it or replace it with new or with a recycled one.

If your module was not damaged, then there are places where it can be reset (to remove the stored crash data) - that will be a lot cheaper than buying brand new.

Next it will be necessary to reset that light.

Assuming that your SRS module is ok and the light still shows, then there is a fix for that.

Try and find someone with the Honda Diagnostic System to run a check on your airbag modules so we can be certain that the SRS module is in order, so we can face the light issue, it can fixed on the cheap without having to go to the dealer. But I don't want liability associated with turning off the light when the SRS module is not ok.

As for the faulty cigarette lighter, we need to check the wiring diagram for vehicle, the associated wiring harness and fuses to make a judgment call!

NOTE: IF YOU OWN A HONDA OR ACURA, BE VERY GENTLE AROUND POTHOLES, SEVERAL MODELS WILL DEFLATE THE AIRBAG JUST BECAUSE OF THAT JOLT WHEN YOU HIT A POTHOLE, UNLESS YOU DON'T MIND THE ADDITIONAL AVOIDABLE EXPENSES

consultancy:
these are screenshots i got of the dashboard from a video of my car in my phone. but at the time i made this video, the airbag light had not appeared. so i got another picture from the Internet of the exact airbag light that has now appeared on the dashboard. i hope you understand

That's an SRS Warning Light.

Was anything else replaced apart from the faulty side curtain airbag?

Or just the side curtain airbag was replaced

consultancy:
i am currently away from the car right now, but i hav d dashboard photo on my phone, but i dnt have that of the airbag light

is it an SRS light?

consultancy:
please brethren what could make a car cigarette lighter suddenly start to produce low voltage. low voltage in the sense that when i plug my phone in, it chargers for 10 seconds and stops and starts again and stops and continues like that in a loop. it was charging perfectly well before. i noticed this after i ran into a big pothole and the driver side curtain airbag deployed. a new airbag was fixed, but the airbag light remained displayed on the dashboard. car is acura mdx 2004

Please kindly post a picture of your dashboard so I can verify some facts before going to offer advice, i want to see the airbag light you are speaking of

DO'S AND DON'TS

Before removing plugs, inspect the surrounding area for collected debris. This must be cleaned before the plug is removed.

If this debris finds its way into the cylinder or the plug seat, you could end up with damaged piston or cylinder walls, or correct sealing and heat transfer between the plug and the cylinder head will be next to impossible.

phibetakappa:
Can the idling speed be increased using the diagnostic machine. The car is a 2007 VW Touareg {gasoline} V6.

Have you consulted your manual? to confirm that the idle is not within specifications?

This may be a problem known to the manufacturer.

Please investigate this:

TSB DESCRIPTION: VOLKSWAGEN: GASOLINE ENGINES HAVE ROUGH IDLE, HAVE SIGNIFICANT LOSS OF POWER OR STALLING WITH REDUCED PERFORMANCE.

DATE REPORTED: FEBRUARY 10, 2012

NHTSA REFERENCE: #10043602

TSB REFERENCE: #TB-01-12-04

Some more pointers to assist you:

Spark plugs? when last changed?
Coil change? when last changed?
EGR valve full of carbon? Can it be cleaned?
Dirty injectors?

phibetakappa:
The idling speed is low (680 rpm) and the makes the engine stall during idling.

Do you have any codes that might suggest any underlying problems to be resolved before doing what you want to do? such as vacuum leaks.

You have got to tune up the engine first to eliminate a poorly running running engine before going this route you are suggesting - team up with a trusted mechanic to sort that out first, before trying what you are thinking of.

DO'S AND DON'TS

HOW TO CHANGE BATTERIES

The negative battery cable(black) should be removed from the old battery before the positive battery cable(red) is

The positive battery cable(red) should be installed in the new battery before the negative battery cable(black) is

Take precautions to ensure that there is no spark or arc near the battery! It can explode or you can short-circuit important components resulting in expensive repairs

DO'S AND DONT'S

It is absolutely wrong to change spark plugs when an engine is hot!

Plugs have steel shells
Most engines have aluminum cylinder heads
So
The steel shell of the plug can destroy the aluminum cylinder head of the engine if it is installed or removed when the engine is hot
By allowing the engine to cool completely, you prevent heat expansion locking the plug into the head and thus ruin an otherwise perfect setup (not forgetting digging a deep hole in your pocket)

How it Works: The Computer Inside Your Car

A maze of wires and computers is the key to your vehicle's deepest secrets. The Controller Area Network, or CAN, is incredibly complex, but here's what drivers should know about how it keep your car's components connected.

We get asked a lot of questions about the bits and pieces of cars that squeak and rattle and break—everything from why is my wheel going clickety-clack to how do I get rid of this rodent smell. But for some time now we've seen our inboxes stuffed with questions on the failings of electronic components. That says something about the technological progress of the automobile. Vehicles are increasingly behaving like computers with wheels, so it's time for a discussion of a little-known aspect of your car: its computer network. In the past we would have called it the electrical system, but its mission has evolved way beyond simply moving dumb electrons. Collectively, these electronics are known as the Controller Area Network, or CAN, but, to be specific, the system of wires and software protocols acting as the connective tissue between a vehicle's computers and sensors is known as CANbus. CAN allows cars to be smarter, cheaper, and capable of doing some slick stuff that wouldn't otherwise be possible.

An Infrastructure for Info

We talked to Eric Paton, a technical specialist at Ford, about the intricacies of CAN. Paton says, "If there's one thing drivers should know when getting into a car, it's that everything seems simple, but beneath the covers it's incredibly complex." The design of CAN is similar to that of a freeway system. Data move like vehicles from high-traffic highways to local roads via on and off ramps. Thousands of data points traverse this freeway at any time along any given stretch and can get off at any exit. Throughout the car are various computers called electronic control units, or ECUs—the traffic lights and intersections of our road-system analogy. Each ECU has several jobs: controlling the engine or transmission, rolling up windows, unlocking doors, and the like. These computers have sensors and switches wired in to detect variables such as temperature, pressure, voltage, acceleration at different angles, braking, yaw and roll of the vehicle, steering angle, and many other signals. When an ECU needs a signal from a sensor connected to an ECU elsewhere in the car, that's where CAN comes in.

Like a freeway, the CANbus network allows data from all the sensors and computers to circulate around the car at all times. Each computer transmits all its sensor and programming information constantly—as many as 2000 signals are floating around the network at any time, whether they're being requested or not. At the same time, each ECU "listens" to the network to pluck out pieces of information it may need to carry out its work. There is no central hub or routing system, just a continuous flow of information that's always available to the ECUs.

Take, for instance, power sliding doors, a common feature on modern minivans. These doors are operated by an ECU called the body control module. Sensors constantly report whether the door is open or closed, and when the driver pushes a button to close the door, the signal from that switch is broadcast across the network. When the ECU gets that signal, however, it doesn't simply close the door. First, it checks the data stream to make sure the car is in park and not moving. If all is well, it then gives a command to a power circuit that energizes the motors used to close the door. It goes even further, though—the ECU then monitors the voltage consumed by the motors. If it detects a voltage spike, which happens when a door is hindered by an errant handbag or a wayward body part, the ECU immediately reverses the direction of the door to prevent potential injury. If the door closes properly, the latch electrically locks the door shut. In the old days, this would have been an engineering feat. Just electrically powering the doors would have required dedicated wires running between the shifter, the door switch, and the motor.

Before CAN was developed in the mid-'80s, every time an automaker added an electronic feature, like, say, heated seats, new, dedicated wires had to be added just to connect the heaters to a dash-mounted switch. Over the years, more features meant more wires, until there were literally miles of wire in wrist-thick vines snaking all over the car. With CAN, the seat heaters and the switch that powers them don't have to be directly wired together. They can simply "talk" over the existing CAN network—no special wires needed. What is needed, however, is some additional programming to get all the devices networked. It's a choice to shift toward programming complexity over physical complexity. CAN has made software development more challenging, but it has had many more positive effects: significant cost savings to the consumer, much lighter weight, reduced reliance on rubber and copper resources, and far better reliability with fewer wires to break over time. Those attributes may be important from a technical standpoint, but the most profound effect of this shift toward programming is on vehicle diagnostics and software updates.

Car, Heal Thyself

The shrinking of the car's wiring harness and other benefits were not the main impetus for the creation of CAN. As pollution requirements matured in the late 1970s, the National Highway Traffic Safety Administration and the California Air Resources Board demanded ways to monitor the effectiveness of vehicle-emissions-control systems. The result of that directive was the standardized On-Board Diagnostics protocol (now in its second generation, known as OBD-II) that required a CAN network to efficiently connect to all the engine sensors for a self-diagnosis. With this interconnection, a designated ECU can watch the network for problem reports broadcast to the network as OBD-II codes. If an ECU detects a problem, it broadcasts it as an alphanumeric code and the Check Engine light is turned on. Modern cars carry out these self-checks any time the car is running. Anyone with a handheld code reader (see Digital Diagnostics) can plug into the standard 16-pin data port in the driver footwell and retrieve fault codes. An Internet search will usually explain the fault or at least give a hint at the problem.

That same data port also comes in handy if a manufacturer uncovers a computer glitch or wants to modify how the car operates. For example, a carmaker may develop an algorithm for smoother transmission shifts. Installing it in any customer car is as simple as a dealer technician plugging his computer into the data port and uploading the new software. Before CAN, this would've meant physically replacing an ECU.
Peeking Behind the Digital Curtain

The heavy tinkerers out there know all about the ability to reprogram, or hack, a car. Manufacturers frown on the practice, of course—it will void your warranty—but not everyone can resist the urge to reverse-engineer code and make a few changes. Unless you're sporting a computer-engineering degree, hacking into the system directly is inadvisable (if you accidentally grenade your engine, you'll be left with a car-shaped driveway ornament), although some aftermarket products make interacting with your car's network quite rewarding, especially if you're a speed freak. Mechanics in hot-rod shops, who modify engines for more horsepower, have been successfully reprogramming cars for at least a decade. But, remember, they're professionals.

WHAT'S NEXT: Wired Like the Web

Your car's electronics network may be sophisticated, but as the amount of data it handles increases over time, it will have to be upgraded. Most likely, cars will adopt an Ethernet-based system such as VEEDIMS, the one in the high-tech Iconic AC Roadster. VEEDIMS assigns each vehicle component an IP address so that centralized and remote computers can pass around huge amounts of information. Attach a cellular connection and data can be beamed to the cloud for analysis. Dealer visits for software upgrades could be replaced by a download. What's holding all this back? Legacy costs. It would take billions to re-create the software. But car Ethernet is coming—someday.

courtesy: popularmechanics

phibetakappa:
Can the idling speed be increased using the diagnostic machine. The car is a 2007 VW Touareg {gasoline} V6.

Why if i may ask would you want to increase the idle speed?

Kjnwancaro:
The car has two sound controls one on radio the other on steering. The one on steering works fine the only problem is the volume knob on radio.

If the steering works fine and the radio doesn't work - i would manage without.

The radio unit was poorly built by Alpine - people have been ranting for years about the poor build, how the heat cycles (from the sun) destabilizes the unit and the poor electronics inside it, and when you use the AC, it sets in motion a series of contractions and expansions that cause the unit to self-destruct after a few years in all those accords, unless you fix the radio circuitry and its location, anything done will be nothing but a temporary fix, it will definitely come back, its not a matter of it, but when.

Infotainment systems electronics:

These would include:


Navigation system
Vehicle audio
Information access


So finally, am done with Wikipedia!