[Aravindpn]

[quote=Aravindpn;4288982]Thanks Jeroen.

Yesterday had a test drive after ECU correction and felt that refinement has increased and also temperature gauge which consistently was on middle in last few years dropped a bit. Will get the car after the elaborate checks by tomorrow.


Hi All,

After this episode, had an issue again. The temperature gauge had stopped working after few weeks and had left it without attending from Oct 17. In first week of March while returning from a Tirumala after a long drive at night the car stalled near lalbagh (thankfully after reaching city). Had experienced an intermittent missing from 6-7 kms before the stall. At night the car refused to start. Parked car there only and left to home in Uber as family was accompanying me. Next day early morning went to the place and to my surprise the car started. The nature of stall was similar to when I had ECM issue in Oct 17. It cranks and after pressing accelerator, rpm is not caught and car dies off. The needle of RPM goes up to 2k and comes downs and stops with a screech. Next day took the car to Nandi Toyota after making up mind (biting the heavy cost)that if needed ECU can be replaced. They checked and confirmed that ECM is fine and if there was an issue with ECM, it would be recorded in a log and there is no log in my ECM. Also they told negative terminal of battery was loose (this is right as my car had this issue) and that may have caused this issue. My stupid questions here, please pardon my ignorance as Iam passionate about cars but technically challenged on working parameters of automobile:

1. Is it right that ECM issues will be recorded in log?

2. Will loose negative terminal cause a stall with the nature as described above?

3. Also had the meter checked up with an electrician and as per him, in Corolla the wiring from temperature sensor passes through ECM, hence there is an issue with ECM which needs to be rectified.

4. Can anyone suggest me a reliable contact in Bangalore who can check the ECM and confirm the status? Is there someone here who have repaired ECM? Will remapping people repair ECM? Will a repair be reliable?

5. Otherwise a very reliable and comfortable car my corolla is, Iam in a big dilemma thinking about what should be my course of action. We have long drives with entire family coming up and thought of stalling nowhere (thankfully this time it was inside city) is making me weak.



Thank You
Aravind

[sudev]

Loose earth = intermittent current

ECM may tend to have erratic behaviour. Also check ground body terminal for rust etc.

OTOH was the car cranking but refusing to start? This would show battery terminals working fine.

[Aravindpn]

Originally Posted by sudev

Loose earth = intermittent current

ECM may tend to have erratic behaviour. Also check ground body terminal for rust etc.

OTOH was the car cranking but refusing to start? This would show battery terminals working fine.

Negative terminal was loose and the terminal came out with a pull with bare hand without using any spanner. Rust should not be there.

The car was cranking but engine was taking time to start. Then I tried pressing accelerator to aid starting while in neutral, that time it will start and rpm will climb little then it will fall off and switch off. The entire span of this will be around 30-40 seconds. Car wont start moving.

[Aroy]

Yes loose battery terminals create all sorts of intermittent faults. I had a similar problem of intermittent failure during starting which was traced to loose cable to terminal lug joint. So the first thing to do is to check both the battery terminal and the cable for loose connection.

[R2D2]

Originally Posted by Aravindpn

Negative terminal was loose and the terminal came out with a pull with bare hand without using any spanner. Rust should not be there.

The car was cranking but engine was taking time to start. Then I tried pressing accelerator to aid starting while in neutral, that time it will start and rpm will climb little then it will fall off and switch off. The entire span of this will be around 30-40 seconds. Car wont start moving.

Which Corolla do you have? the 9G or 10G? Your engine may also be flooded. Check the following:

a) All connections from the alternator to the fuse box and from there to the battery terminals for good fit and no corrosion.

b) Get the alternator checked. Loose wires are not good for the health of the electrical system.

c) Coolant temperature is monitored by the ECU. Is it operational? Does your dashboard temp gauge function normally?

d) ECU connections. The ECU is the large vertically mounted unit next to the air cleaner. Looks like a small pizza box. It has two large connectors fitted on top.

e) Any warning lights coming on in the dashboard cluster?

If the ECU logs an error you will need the ASC to advise further. I do not think (and hope) the ECU needs to be replaced unless the loose electrical connections damaged it. Be careful about sensitive electrical and electronic equipment in modern cars. ECUs are expensive to replace.

[sudev]

Originally Posted by Aravindpn

Negative terminal was loose and the terminal came out with a pull with bare hand without using any spanner. Rust should not be there.

The car was cranking but engine was taking time to start. Then I tried pressing accelerator to aid starting while in neutral, that time it will start and rpm will climb little then it will fall off and switch off. The entire span of this will be around 30-40 seconds. Car wont start moving.

Loose does not mean that it came off by hand but if it was having sufficient contact to pass required current draw by cranking. RPM not climbing could be ECM or throttle body issue. Not easy to diagnose remotely.

[Aravindpn]

Originally Posted by R2D2

Which Corolla do you have? the 9G or 10G? Your engine may also be flooded. Check the following:


a) All connections from the alternator to the fuse box and from there to the battery terminals for good fit and no corrosion.

b) Get the alternator checked. Loose wires are not good for the health of the electrical system.

c) Coolant temperature is monitored by the ECU. Is it operational? Does your dashboard temp gauge function normally?

d) ECU connections. The ECU is the large vertically mounted unit next to the air cleaner. Looks like a small pizza box. It has two large connectors fitted on top.


e) Any warning lights coming on in the dashboard cluster?


If the ECU logs an error you will need the ASC to advise further. I do not think (and hope) the ECU needs to be replaced unless the loose electrical connections damaged it. Be careful about sensitive electrical and electronic equipment in modern cars. ECUs are expensive to replace.

Its 2006 model petrol. 1.8E

Further to the issue, had sent vehicle to ASC of Toyota and as per them a and b are taken care

Temp gauge is not working even now. ASC advised to change cluster which was very expensive. Shown to a local meter repair guy who tried with another meter and in that also temp gauge was not working. So it comes out that its not cluster issue, its an ECM issue. So now ASC of Toyota is saying ECM is fine, meter repair guy and electrician of an independent garage is saying ECM has to be checked for temp gauge issue. My search is for a reliable ECM repair/ check person in Bangalore. Please provide leads if anyone know.

No warning lights even now nor when issue popped up.

The confusion is, after checking the ECU, ASC is conveying that there is no logs under ECM. Hence, they are not advising to replace ECM.

[Aravindpn]

Originally Posted by sudev

Loose does not mean that it came off by hand but if it was having sufficient contact to pass required current draw by cranking. RPM not climbing could be ECM or throttle body issue. Not easy to diagnose remotely.

Yes, I need to find a reliable independent ECM scanning/ repair person in Bangalore, but could not locate till now. Any leads from any one here please.

[R2D2]

Originally Posted by Aravindpn

Its 2006 model petrol. 1.8E

Further to the issue, had sent vehicle to ASC of Toyota and as per them a and b are taken care

So that means teh alternator and related electrical wiring are in good operational condition. So we can rule out those issues.

Temp gauge is not working even now. ASC advised to change cluster which was very expensive. Shown to a local meter repair guy who tried with another meter and in that also temp gauge was not working. So it comes out that its not cluster issue, its an ECM issue. So now ASC of Toyota is saying ECM is fine, meter repair guy and electrician of an independent garage is saying ECM has to be checked for temp gauge issue. My search is for a reliable ECM repair/ check person in Bangalore. Please provide leads if anyone know.

No warning lights even now nor when issue popped up.

The confusion is, after checking the ECU, ASC is conveying that there is no logs under ECM. Hence, they are not advising to replace ECM.

Have you had the coolant temperature sensor checked?? The ECU is a really expensive part! When it comes to diagnosis I'd rather go with the ASC than some road side bloke.

For fault diagnosis and tracing, eliminate potential faults at the signal's origin first. In other words start with the 'sender' of the temperature information (the sensor) and then move on to the next one in the chain possibly the ECU. ECUs don't go bad without some explanation for electrical pulse, moisture etc. Hope nobody disconnected the battery cables when the engine was running to check the alternator!! That's a sure shot way to fry your car's electronics. A word of advice never, ever do that!

Your dashboard temp indicator depends on the sensor as does the ECU. So if that has gone kaput or has loose wiring it will malfunction and cause the ECU to go haywire. In the EFI program one of the key input variables is coolant temperature.

[Leoshashi]

Dear all,

Need a favour from you guys. This Ambassador, my dad's official ride, is a 2004 Model, MPFI, with 1.5L kms on the odo. Offlate, it is having some serious electrical issue. Before surveying it off(sending to scrap), I look forward to your advice which can help us revive this car.

Case History:

1. Car is lying unused since past 5 months, due to starting issues.

2. It sometimes randomly starts, and randomly shuts down.

3. Yesterday, I tried to revive this car. When I tried to crank it, it cranked but didn't start. Cleaned the distributor leads, the car started but suffocated and stalled. I then cleaned the throttle body and IAC(sprayed some throttle cleaner). Lots of crap came out, and despite erratic idling, the car started, idled for half an hour, and we brought it to my parking(a distance of 5kms) without any issues. The driver was in awe, as the car which couldn't idle for 1 minute, was behaving like this.


4. Since today morning, I am noticing a weird issue. When the fuel pump is being primed, sometimes it makes a krrr krrr krr type of sound from engine bay. Sounds like loose contact. Twice, the starter fired on its own(without me cranking).

Also, once while priming, it made a bullet like sound and lots of soot came out.

Mechanics from my MASS came, and they tried to revive the car but in vain.

We have swapped these things from a known good car(but surveyed off due to rust), but without any success:

1. ECM
2. Coil or igniter assembly(a rectangular box near the brake reservoir, and it goes into the distributor)
3. Throttle body
4. A weird thing which looks like an IAC valve, but also has a blow by pipe going into it.
5. Relays.

Now the issue is, no current is reaching the plugs.

Please help.

Videos:

1st start, when it came to life yesterday:

https://www.youtube.com/watch?v=w7nexzvBvKw

Weird issue:

https://www.youtube.com/watch?v=5PEvZQ1VXJU

Regards,
Shashi

PS: The alternator light on the dashboard keep flickering at idle.

[Sutripta]

^^^
Going by the concept of shortest (=easiest to check, or least expensive to check) job first, fit a fully charged preferably newish battery, disconnect the alternator, and then see what happens.

Regards
Sutripta

[Jeroen]

I would go with Sutripta advise as that is most likely the easiest to check. Also, check all electrical connections on the battery for sign of corrosion. Check the various earth straps for corrosion.

You would be surprised how many of these sort of problems can be caused by simply not getting the right voltage to the various electronic components. So battery and connectors in the power supply circuit.

The best thing would be to hook it up to an OBD scanner. With these symptoms it is very likely you will have various error codes and you can quickly hone in on the components that cause the errors, rather then hit and miss approach of replacing random parts.

One other possible cause could well be the camshaft and or crankshaft sensor. You can test most of these with a multimeter, but again it would show an error code if there was anything wrong.

Low voltage due to a poor battery and or connector is likely to throw an error code and might give an idea whether it's battery versus a specific component.

Good luck
Jeroen

[Leoshashi]

Thanks a lot for replying.

Originally Posted by Sutripta

^^^
Going by the concept of shortest (=easiest to check, or least expensive to check) job first, fit a fully charged preferably newish battery, disconnect the alternator, and then see what happens.

Originally Posted by Jeroen

I would go with Sutripta advise as that is most likely the easiest to check. Also, check all electrical connections on the battery for sign of corrosion. Check the various earth straps for corrosion.

Couple of abnormalities found.

1. Battery, although was showing 12.5V, was discharged. The Bosch C7 is charging it from 25% mark.





2. The terminals were badly corroded. Cleaned them.







3. Couple of points where earthing should happen, were either corroded or painted in the aftermarket. Cleaned them

4. Found insulation damage inside the cabin at some places. This particular one happened due to that zip tie



Currently waiting for the battery to get fully charged.

Regards
Shashi

[Sutripta]

Would have been happier if you had temporarily hijacked a newish battery from some other vehicle. Remember to disconnect the alternator.

Intermittent connection problems are notoriously difficult to track down. In a modern automobile it is generally preferable to change the full wiring harness. In an out of production car, cost and availability normally mean the vehicle is scrapped.

Good luck.

Regards
Sutripta

[Leoshashi]

First of all, thanks a lot for the ideas given.

Originally Posted by Sutripta

Would have been happier if you had temporarily hijacked a newish battery from some other vehicle.

Sir this battery was just 5 months old, and the newest battery which I could find. This battery was installed just when the car started giving issues. However I charged it to the max before installing.

Remember to disconnect the alternator.

For sure sir. The first start today happened without the alternator. The car started in a single crank, rpm raised but died down too. Since we had spare throttle body, my Maruti SA had a detailed look and found out it uses some sort of fuel/air mixture screw

We started it again, but this time kept fiddling with the screw. The RPM stabilised. Then after the car idled easily, we switched it off and connected the alternator. The car started, idled for 5 minutes and then died on its own. Cranks didn't happen. I then disconnected the alternator and again it started without any issue. Was missing in the lower revvs, but didn't die down and we managed to drop it again to the office parking(5kms distance).

For the time being, we have disconnected the negative terminal of the battery. Also sourced a working alternator from the same scrapped amby from whom we sourced parts yesterday. Since the exhaust manifold was hot, we'll be doing the swap tomorrow.

Regards,
Shashi