nurey:
i dont know what they mean by "if check engine light doesnt show car wont start" i used a nissan and it doesnt show the check engine light and it starts fine, i believe this is to suffice they dont know what they are doing.

Check all the fuse in the fuse box by the bonnet, there is an EFI fuse that gets burnt when you roll engine too much while car doesnt start, once that is burnt, the car will never start brain box or not. Also i dont really know the setup of your car but i recently had an issue like yours, it was due to a burnt relay fuse by the fuel pump in the tank then after replacing, i felt a jerk during a 30mins test drive and car stopped, all effort to start it refused until a #50 naira worth of fuse was replaced please dont use wire to join the fuse, the kind of heat that will emanate from that connection if not replaced soonest can burn a car to ashes.

Lexit:

Oga nurey, if I understand you very well, brain box matter should be ruled out for now then. Well as the guy observed, the CEL normally comes up when I roll the engine with other dashboard lights until now. ANother thing I didnt add is that I stopped over to fuel the car while going yesterday without stopping the engine. Hope that can affect the start issue? May be I should ask another electrician look into i t then.

mayor2013:
Check EFI fuse if OK check ecu aka brain box. Your Kazeem who manipulated your alternator has Fried your ecu

Lexit:


If at all the ECU is damaged, may I know if it can be repaired please?

mayor2013:


No sir. Absolute replacement

Lexit:


Thanks all. We later discovered that the brain box works after changing one of the fuses. The check light comes up now when rolled. But the problem that still persists is that the car cranks well but not starting. Different technicians around the place have checked but can't find the reason the car is not starting. The car has been scanned and no error code.
Cc: Nurey, Gazzuzz, honmusa

Lexit:


Thanks all. We later discovered that the brain box works after changing one of the fuses. The check light comes up now when rolled. But the problem that still persists is that the car cranks well but not starting. Different technicians around the place have checked but can't find the reason the car is not starting. The car has been scanned and no error code.
Cc: Nurey, Gazzuzz, honmusa

GAZZUZZ:
check efi fuse. If OK replace engine ecu.

honmusa:
This is a very simple issue. Use a professional scanner (not all this toy scanner )to scan all electronic control modules that is on the car and any one you can not access is down ie if the ECU is not available to access then it is faulty.
Cos if truly there is no check engine due to ECU issue then it must be offline .

GAZZUZZ:


looking for trouble

Inception:


Scanning won't solve this oga. The ECU cannot be accessed for codes in this kind of situation.

mayor2013:
Location of this ride

Inception:


I think what he should check is the alternator fuse, that fuse is the one that is usually sacrificed ( sometimes with other fuses tho) when this kind of situation happens. The alternator fuse is very well integrated(bolted) and secured in the engine fusebox.

Inception:


Scanning won't solve this oga. The ECU cannot be accessed for codes in this kind of situation.

honmusa:

Bros , scanning for modules is what i mentioned not looking for dtc !!!there is a huge wide difference between the two !!!
You want to scan for modules to see all the available ecu that are online ,you are not chasing for codes (dtc) everyrywhere as being done by those kazeem that have access to scanner !!!this is not a feature you can see in your $5 dollar scanner!!!!you will need a little bit high end tools to achieve this,you dont need a brain to do this just to see if your ecu is powered up !!
You can achieve bypass a lot of electrical torubleshooting if you invest in the expensive smart scan tool ,those cheap chinese scraps scanners you are use to are useless !!

Inception:


What modules if I may ask? The issue here is the car not starting, strongly implying a powertrain issue. This localizes the problem to the only one module: the ECU and everything it controls/manages(since we are talking Toyota here and not BMW). There are therefore 3 possibilities here: Bad Ecu fuse, Bad Alternator fuse or bad ECU. Following the explanation of the OP, (where there is a short of that kind, It is very likely that the Alternator fuse will go out first, then the Ecu fuse before such wahala gets to the ECU itself. It is called 'Failsafe'

Another possiblilty could be the immobilizer if the car is equipped with one .

Inception:


What modules if I may ask? The issue here is the car not starting, strongly implying a powertrain issue. This localizes the problem to the only one module: the ECU and everything it controls/manages(since we are talking Toyota here and not BMW). There are therefore 3 possibilities here: Bad Ecu fuse, Bad Alternator fuse or bad ECU. Following the explanation of the OP, (where there is a short of that kind, It is very likely that the Alternator fuse will go out first, then the Ecu fuse before such wahala gets to the ECU itself. It is called 'Failsafe'

Another possiblilty could be the immobilizer if the car is equipped with one.

Inception:


What modules if I may ask? The issue here is the car not starting, strongly implying a powertrain issue. This localizes the problem to the only one module: the ECU and everything it controls/manages(since we are talking Toyota here and not BMW). There are therefore 3 possibilities here: Bad Ecu fuse, Bad Alternator fuse or bad ECU. Following the explanation of the OP, (where there is a short of that kind, It is very likely that the Alternator fuse will go out first, then the Ecu fuse before such wahala gets to the ECU itself. It is called 'Failsafe'

Another possiblilty could be the immobilizer if the car is equipped with one.

mayor2013:


I disagree with your last paragraph. If such is always the case then why do we have cases of fried ecu. Your statement doesn't apply to all cars. Some ecu producers make use of zender diodes( voltage protection device) i.e two diodes connected back to back.which helps to forestall any reversed polarity of current coming in

honmusa:

Yes is still the same engine computer module ,i am not interested in the other modules .this is just a quick troubleshooting tip to check the types of fault with ECU .
If the ECU is down or unavailable relatively to other ones ,that is pointer to a power feed or ground issue with the ECU and this will help you checking for all those instead of wasting time probing the ignition and the fuel injection terminal on the ecu or even disturbing the immobilizer. This is just a sharp sharp quide to the type of ecu issue before you going down to the specifics eg fuse,open circuit ,shortcircuits etc .Hope i have made myself clear on this!!!

Inception:


You can have expensive tools and diagnostic machines and still mess things up. Understanding how systems work from first principles is the most invaluable tool any technician can ever own. In fact a 5 dollar 'Chinese' scanner will give me the same result you are explaining here: It will simply not power up!

honmusa:

seems you dont even understand this first principle you are talking about cos the reason why your $5 crappy scanner will not power is not because absence of power feed to the ecu but a simple issue of power feed to pin 16 of your car DLC and is a totally different power supplies thru different fuses.
Check the two circuit below and compare !!
The first circuit is the power feed circuit for engine control unit and the one below is the Power feed circuit to DLC all for this for toyota rav 4 2007
and the answer to your simple question your crappy scanner will not connect is because the PIn 16 power feed on the DLC is not there (blown 7.5A fuse labelled obd fuse or bad ground on pin 4 or 5 on the DLC
if you are my apprentice i wont even allow you to change my daughter toy car battery because you still a kazeem on electricals !!!

Inception:


Well boy i do ( better than the google knowledege you spewed here) It is still the same outcome(ECU having no power). It is now obvious that you are simply blabbing in your response just to feel cool with yourself.

Now boy, picture this: I believe in people who understand both ends of the spectrum when it comes seeking solutions to problems without throwing their weight in the mix. That is why people like Siena were sorely missed, and people like Gazzuz are just soaring higher in their endeavors by the day

Thank God I am not your 'apprentice' because with the little i have seen here, you are too acidic and poisonous in your reasoning!

I am in my house, oya come and beat me

honmusa:

Boy ?
wetin person eye no go see for public forum like this !!!!nawa ooo,there is God sha!!!

Lexit:
Nairalanders please come to my help. My Toyota Rav 4 2007 model had alternator issue days ago, which required I take it for repair. When it was time to fix it back, the guy fixing it made a mistake in the wires connecting the alternator's socket. The battery charges again but would drain after parking it for some minutes. When I took it to an electrician (rewire) he complained about the spark on the battery saying it was too much. He tried checking the cause of the battery drain by checking all the fuses in the car with no solution. When it was getting to night time yesterday, he asked me to go with the car and return today. We managed start the car and on my way going back home, the car went off on the motion. I tried starting it; it cranked but not coming up till my battery drained off again. I looked for another electrician this morning to help look into the situation. The guy checked the plug, fuel supply and other things that might make it start. Later on he discovered that the CHECK ENGINE light, which should come up with other lights on the dashboard when the ignition is turned on does not show. He then concluded that the brain box is bad. According to him, if the check light engine does not show with other lights on the dashboard when the ignition is turned on, the car cannot start. He already removed the brain box but I am finding it difficult to believe it is the culprit.

Any one with an idea of what could be wrong with my car?
cc: honmusa, nurey, gazzuzz

honmusa:

@op
I will help you diagnose this issue and even fix it free of charge if you can book a convenient time with me this week !!!

No that's the cartalk spirit