Our 2003 G35 Coupe has encountered a problem. When the headlights are on the dashboard lights do not work. I do not have further details as my wife drives the car. I do know that nothing has happened to the car, ie accidents, etc., that would have caused a sudden electrical problem.

I hate to go and pay a dealer to troubleshoot. Any ideas on what to look for or check? I'm hoping is something fairly straightforwrd.

When you turn on your headlights the dashboard lights will automatically dim to prevent compromising your night vision. This is a pain for people who like to drive with their lights on during the day (as a safety measure) because the dimmer dash lights are difficult to see during the day, especially if you're wearing sunglasses. You can adjust the brightness of the dash display using the +/- button on the dashboard nearing the steering console. Trying making it brighter to see if that fixes the problem. It may be that someone adjusted it all the way to the lowest position and once you turn on the headlights the dash lights almost disappear. Good luck!

Thanks. I have also determined that the approximate time this problem started was close to when we had a new battery installed. Could this have anything to do with it?

Your theory encouraged me, then, I remembered the dashboard lights are not working at night either. It must be something more involved than the dimmer switch

Please excuse the bump, but, I am hoping that someone here is aware of this problem and might have insight on what needs to be done to correct. I really don't want to have to get a dealer's service dept involved. Thanks again for any thoughts or comments.
David

The dashboard lights and other accessory functions are control by the BCM(body control module). Remove the the positive cable from the battery and replace after 5 minutes. This will reset the BCM(it will also reset any programming such as your radio presets). Hopefully this will solve your problem. It did on my 03 coupe. If it solves the problem but reoccurs at a later date then the BCM will have to be replaced(approx $300 I think). Good Luck!

The battery disconnect/re-connect did not solve my problem. I did determine two more bits of information though:

1. The positive battery cable clamp/connector was not secure. I could pull the clamp off of the post with no effort. Also, there was corrosion on the post. Could this poor connection have caused the BCM to fail?

2. The dashboard lights work when the parking/marker lights are on. When I turn the headlights on, either manually or with the auto feature, the dashboard lights go out.


Any ideas how to troubleshoot the BCM? I am thinking that if it were bad more systems would be malfunctioning.

Thanks again for the responses.

Hello,

What was the solution to your problem? I am having the same issue however, I can see evidence of rats being in the engine and eating the wires. Unfortunately this has happened to me before, different symptoms though.
So was it the BCM module?

Rich

Hi. I'm having the same problem and I need to know the solution ASAP. Moving out of state tomorrow.

jdlynch wrote:The battery disconnect/re-connect did not solve my problem. I did determine two more bits of information though:

1. The positive battery cable clamp/connector was not secure. I could pull the clamp off of the post with no effort. Also, there was corrosion on the post. Could this poor connection have caused the BCM to fail?

2. The dashboard lights work when the parking/marker lights are on. When I turn the headlights on, either manually or with the auto feature, the dashboard lights go out.


Any ideas how to troubleshoot the BCM? I am thinking that if it were bad more systems would be malfunctioning.

Thanks again for the responses.

Did you or anyone find the solution for #2?

Philip

The dashboard lights work when the parking/marker lights are on. When I turn the headlights on, either manually or with the auto feature, the dashboard lights go out.

What is the solution?

priddle wrote:The dashboard lights work when the parking/marker lights are on. When I turn the headlights on, either manually or with the auto feature, the dashboard lights go out.

Duplicate thread deleted.

All modern cars have a dimmer switch for the dashboard lights. It doesn't do anything until your headlights come on. It sounds like the dimmer switch has been turned to it's lowest possible setting, which is off.

my car was doing the same thing. took it out for the first time at night only to find out my dash went completely dark. went to youtube and discovered it's the rheostat switch! it had been turned all the way down. turned on my lights , turned up the rheostat and voila--well lit dash!