No foglight indicator after dead battery

[Mach VII]

Follow this and see if the indicator comes on...

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[Torched10]

Follow this and see if the indicator comes on...

Don't see any icons fir fog light just lots of track Info

 

[Mach VII]

Don't see any icons fir fog light just lots of track Info

It should make all indicators illuminate....

 

[Le Mans]

It should make all indicators illuminate....

Thank you I'm going to try


I assume the indicator lights are not separately fused?

 

[Boyd]

@Le Mans

The fog lights are all powered by the BCM. BCM is controlled by the fog switch on the headlight switch panel by supplying grounds. According to OP, this all works fine, front & rear.

There is no schematic nor fuse for this single indication in the instrument cluster. It uses one of the fuses labeled for the BCM. I believe fuse F15 in the BCM. But that powers a LOT of stuff. So we believe that is fine.

There is a High Speed Canbus (digital data bus) system that works on a Module Communications Network. The instrument panel indicator lights are fed by this data system from the BCM. There are no relays and no individual wiring for the fog light indicator. This is not an old school system... it is modern electronic digital data busses.

AFAIK, theres 3 things that could affect the fog light indication. BCM, HS CANBUS wiring or Instrument Cluster. Almost certainly not wiring... if it was, there would be a ton of hard failures.

I agree with the other poster that the problem was most likely created by trying to supply constant power while replacing a main battery, probably creating a voltage spike. Dont do this. Just replace the battery. The car can take care of itself, and will even relearn the battery state if left alone for 8 hours.

Suggestions:
1. Disconnect the battery. Turn on headlights. Let car sit for a while... I'd give it an hour. Turn lights off, reconnect battery. Do a BCM reset.
2. Get into the Engineering Test Mode... there are several you tubes on how to do this. There is a dashboard lighting test in there... see if the fog light indicator comes on. The test mode likely uses a different circuit in the BCM than the regular indication circuit (not known for a fact). So if the fog light indication tests good, I might think its a BCM issue. If it does not test good, I might think its an instrument cluster issue.

Dealer might be able to do further tests or troubleshooting into the BCM if needed.

Hope I've helped a little bit. Good luck in finding the problem.

 

[Skye]

Thinking of disconnecting the battery and de-energizing...With the car off, I wonder what would be the effect of removing the headlight switch and letting it sit. Pretty simple to access and remove. Maybe even go to accessory mode while the switch is out, then turn the car off, before re-installing. Something to help the car realize the module is not there and help with the reset of logic to that specific pathway.

 

[Boyd]

Thinking of disconnecting the battery and de-energizing...With the car off, I wonder what would be the effect of removing the headlight switch and letting it sit. Pretty simple to access and remove. Maybe even go to accessory mode while the switch is out, then turn the car off, before re-installing. Something to help the car realize the module is not there and help with the reset of logic to that specific pathway.

Its possible. There's no telling what the logic really is that can create a reset. But... The headlight switch works by supplying grounds of individual circuits to the BCM. When the BCM sees that particular ground, it energizes that particular circuit according to its programming. So disconnecting the switch panel would just remove all grounds. Still, considering the OP really needs this indicator light to work to pass inspection, its worth a try.

 

[Le Mans]

@Le Mans

The fog lights are all powered by the BCM. BCM is controlled by the fog switch on the headlight switch panel by supplying grounds. According to OP, this all works fine, front & rear.

There is no schematic nor fuse for this single indication in the instrument cluster. It uses one of the fuses labeled for the BCM. I believe fuse F15 in the BCM. But that powers a LOT of stuff. So we believe that is fine.

There is a High Speed Canbus (digital data bus) system that works on a Module Communications Network. The instrument panel indicator lights are fed by this data system from the BCM. There are no relays and no individual wiring for the fog light indicator. This is not an old school system... it is modern electronic digital data busses.

AFAIK, theres 3 things that could affect the fog light indication. BCM, HS CANBUS wiring or Instrument Cluster. Almost certainly not wiring... if it was, there would be a ton of hard failures.

I agree with the other poster that the problem was most likely created by trying to supply constant power while replacing a main battery, probably creating a voltage spike. Dont do this. Just replace the battery. The car can take care of itself, and will even relearn the battery state if left alone for 8 hours.

Suggestions:
1. Disconnect the battery. Turn on headlights. Let car sit for a while... I'd give it an hour. Turn lights off, reconnect battery. Do a BCM reset.
2. Get into the Engineering Test Mode... there are several you tubes on how to do this. There is a dashboard lighting test in there... see if the fog light indicator comes on. The test mode likely uses a different circuit in the BCM than the regular indication circuit (not known for a fact). So if the fog light indication tests good, I might think its a BCM issue. If it does not test good, I might think its an instrument cluster issue.

Dealer might be able to do further tests or troubleshooting into the BCM if needed.

Hope I've helped a little bit. Good luck in finding the problem.

thanks for your extensive answer Boyd

I just realized that when resetting the faults via OBD, there was also a test mode.

The fog lamp indicator came indeed on !!

With sweat in my hands i will disconnect the battery again ( with the lights on,)

Or first disconnect and then light on ?

And then connect them again after min an hour with the lights off


keep you posted

 

[Boyd]

thanks for your extensive answer Boyd

I just realized that when resetting the faults via OBD, there was also a test mode.

The fog lamp indicator came indeed on !!

With sweat in my hands i will disconnect the battery again ( with the lights on,)

Or first disconnect and then light on ?

And then connect them again after min an hour with the lights off


keep you posted

Great! Ok, so you know the lamp (or LED) is good.

Turn the headlight switch on AFTER disconnecting the battery. Turn the headlight switch off BEFORE re-connecting the battery. Fewer voltage spikes.

Are those fog lights stock or aftermarket? Did the fog light indicator work for certain before the battery change?

Yes, please keep us posted.

 

[Le Mans]

Great! Ok, so you know the lamp (or LED) is good.

Turn the headlight switch on AFTER disconnecting the battery. Turn the headlight switch off BEFORE re-connecting the battery. Fewer voltage spikes.

Are those fog lights stock or aftermarket? Did the fog light indicator work for certain before the battery change?

Yes, please keep us posted.

Okee. Thx,

I think stock, but not sure . Worked fine before battery change

 

[Le Mans]

negative pole loose now wait

After connecting, wait 8 hours for test, and only then reset BCM?

 

[Le Mans]

Well..


just reconnected battery. lights out first.

Then BMS reset.

Battery indication flashed neatly 3x

Unfortunately.... no indication :(

Still having to reset everything I was afraid of: Language...Bar / psi. ..Sync.

I'm even more afraid of all the previous failures...rear window defroster. Seat heating. Air conditioning. etc etc
But just maybe.... maybe they'll come back after 8 hours


pffffff.

 

[Boyd]

OK, not looking good.

I am now suspecting you have a BCM issue. Could be that you had a voltage spike that toasted the fog light indication transistor. Of course, I dont know everything there is to know about these cars. I would take it to a dealer and allow them to investigate.

Tell them:
1. The fog light indicator is not working after a battery change. Fog lights operate normally.
2. List everything else that needed to be reset.
3. You did the diagnostic light test and it showed the light was good.
4. You did a battery disconnect and it did not help.

These are all troubleshooting items that may help them.

Sorry I could not help more. Good Luck.

 

[Le Mans]

OK, not looking good.

I am now suspecting you have a BCM issue. Could be that you had a voltage spike that toasted the fog light indication transistor. Of course, I dont know everything there is to know about these cars. I would take it to a dealer and allow them to investigate.

Tell them:
1. The fog light indicator is not working after a battery change. Fog lights operate normally.
2. List everything else that needed to be reset.
3. You did the diagnostic light test and it showed the light was good.
4. You did a battery disconnect and it did not help.

These are all troubleshooting items that may help them.

Sorry I could not help more. Good Luck.

In any case, thank you very much for your efforts so far

When toasted the fog light indication transistor, it wouldn't burn during testing, would it? or?

 

[Skye]

An additional thought: what about going to the dealer for a re-flash, then reset of the BCM software?

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