E46 Alternator/Voltage Regulator Failure Symptoms

[wingzee]

Hi all,Car decided to shuts off/died today when I was driving slow looking for a space to park (about 10 km/h). Car was just started about a minute or so when engine died when I turned on the air-conditioning. Decided to put gear back in P, restarted and it cranks up with only one crank.Couldn't replicate the same issue again after that and when hooked up to BMWscanner & INPA, no errors were detected. Hence, I have ruled out the camshaft sensor.Many have told me it may have been the alternator as I often have this pulsating OBC backlight when driving which may points yo unstable voltage?Anyone can advise what are the symptoms of a failing alternator? Hve been through the US forums and some pointed that it could be the voltage regulator too.

 

[Alex5522]

what are the symptoms of a failing alternator?

My experience on the alternator kong was most of my instrument cluster light was lights up and my battery no more charging. Solution was repair/change the alternator and every things comes bck to normal.

 

[e34_lover]

Use a multimeter across the battery terminals to see what the voltage is at idle. It should be around 14V. Anything less than 12.8V or so means your alternator is not putting out enough voltage.

 

[wingzee]

Use a multimeter across the battery terminals to see what the voltage is at idle. It should be around 14V. Anything less than 12.8V or so means your alternator is not putting out enough voltage.

I did a check through my OBC and it shows 12.8V before starting the engine and 14.2V during idle after started. Is that normal?

 

[astroboy]

I did a check through my OBC and it shows 12.8V before starting the engine and 14.2V during idle after started. Is that normal?

Looks healthy, that's presumably without aircond on? Because mine only register 13.8~14.0 during charge.

 

[Strider74]

Bro, might be agood idea to check for loose cables.
With the rattling, uneven road and pothole that our roads are famous for maybe the cable/wire becomes loose.
Try to tighten the nuts and screws.

Just my 2 cents.

 

[wingzee]

Looks healthy, that's presumably without aircond on? Because mine only register 13.8~14.0 during charge.

Yeap that's without anything turned on. Just the engine. Will do another check tonight with aircond, lights and radio turned on.

 

[Alex5522]

Check your alternator carbon brush, it might be wont out.

Refer pics borrow from bro moots below;

Replace the carbon brush can save you a lot

 

[wingzee]

Check your alternator carbon brush, it might be wont out.

Refer pics borrow from bro moots below;

Replace the carbon brush can save you a lot

Thanks bro Alex! Any idea where can I get mine replaced?

 

[Alex5522]

I am not sure at KL area maybe some one in KL can recommend, fyi i did it at my friend's workshop at Senawang Light Ind Area almost 2 yrs bck.

 

[tweiboon]

Thanks bro Alex! Any idea where can I get mine replaced?

This 1 can get from ebay. As i saw more than RM200. It cannot just change the carbon due to it is not letting u to open the carbon. Must change whole set as the picture shown above.

 

[Alex5522]

Changed mine almost 2 yrs back and use my original alternator till now.
Only some SKL tell cannot change..

 

[Alex5522]

Another pic from bro moots which show the carbon brush

 

[B33mEr]

Could it be your idle control valve that needs cleaning maybe?

Also Bavarian Auto is selling Bosch alternator for RM850 new

 

[wingzee]

Could it be your idle control valve that needs cleaning maybe?

Also Bavarian Auto is selling Bosch alternator for RM850 new

I have this erratic idling issue too during cold start but not sure if that's related to my current problem?

Got home and retested via OBC and results as below:

- Engine on, idle but nothing else on: 14.3v
- Engine on, lights on, radio on: 14.2-14.3v
- Engine on, lights on, radio on, air-cond on: 14.1-14.2v
- All the above plus interior lights on: 14.0-14.1v

 

[B33mEr]

I have this erratic idling issue too during cold start but not sure if that's related to my current problem?

Got home and retested via OBC and results as below:

- Engine on, idle but nothing else on: 14.3v
- Engine on, lights on, radio on: 14.2-14.3v
- Engine on, lights on, radio on, air-cond on: 14.1-14.2v
- All the above plus interior lights on: 14.0-14.1v

Sounds like ICV ... http://www.bimmerwerkz.com/forum/3-series-e46-e90/2000-328i-rough-idle-when-cold-43652.html

 

[e34_lover]

Your voltage looks fine. Don't bother changing it unless it starts dropping and you have trouble keeping your battery charged.

Your erratic idling issue does sound like the ICV like B33mEr said. It usually only needs to be cleaned as it rarely fails. You could be experiencing some vacuum leaks as well. The hoses do tend to get old over time. I just bought a meter of hose to fix my leaks!

 

[wingzee]

Your voltage looks fine. Don't bother changing it unless it starts dropping and you have trouble keeping your battery charged.

Your erratic idling issue does sound like the ICV like B33mEr said. It usually only needs to be cleaned as it rarely fails. You could be experiencing some vacuum leaks as well. The hoses do tend to get old over time. I just bought a meter of hose to fix my leaks!

Planning to check on that my next service. But if it's not the alternator, what could be the reason why the engine died?

 

[e34_lover]

Planning to check on that my next service. But if it's not the alternator, what could be the reason why the engine died?

Could be the ICV getting stuck and not letting air in causing the engine to stall. This is based on your symptom of erratic idle though. If it happens again after you clean the ICV or if it even happens again at all then its easier to narrow down the problem.

Right now it is a little difficult to diagnose. Just want to confirm that you said the engine died when the air-conditioning was turned on? Wasn't very clear in your first post. If so, it's a high chance that it is the ICV. When the air-conditioning is turned on, the ECU bumps up the idle because of the drag from the compressor, it needs to get the engine back to the right rpm. If the engine could not get enough air from the ICV opening, it could stall the car.

 

[wingzee]

Could be the ICV getting stuck and not letting air in causing the engine to stall. This is based on your symptom of erratic idle though. If it happens again after you clean the ICV or if it even happens again at all then its easier to narrow down the problem.

Right now it is a little difficult to diagnose. Just want to confirm that you said the engine died when the air-conditioning was turned on? Wasn't very clear in your first post. If so, it's a high chance that it is the ICV. When the air-conditioning is turned on, the ECU bumps up the idle because of the drag from the compressor, it needs to get the engine back to the right rpm. If the engine could not get enough air from the ICV opening, it could stall the car.

Yeap it died the moment i turned on the air conditioning. If that's the case then likely it's the ICV then. Thanks fot the detailed explanation bro. Shall clean it this weekend & see how it goes.