Hello everyone. I have been having an issue with my interior lights not coming on at all during the night time (no dash, no radio, no temp, nothing) and was wondering of a couple possible solutions for it? I already replaced my headlight dimmer switch as one of the pins was burnt up but that did not seem to fix it. I checked every fuse/relay around the car, and still no fix. About 1/10 times I'll go to start my car at night and boom, lights are on but every other time I am left in the dark. Let me know if any of you have a solution, thanks.

 

Do the headlights go from Daytime Running Lights (uses the high beams at a low voltage) to your actual headlights/low beams? What happens if you manually activate your headlights?

My first thought it the light sensor located between the front windshield and the dash pad (looks like a little bubble) if it has failed. That is what tells the BCM to activate these lights.

 

Yes, my DRLs turn off at night and my normal headlights come on. Dash lights still don’t work in manual mode but the headlights do. I have replaced that little bubble sensor you are talking about as well, but still no luck. My battery connections are all tight as well, so maybe a bad BCM possibly or some frayed wiring?

 

Off the top of my head, I am not sure. I am curious if the shop book has a diagnostic for this. I wonder if it might be a sign of a bad BCM.....

 

I actually checked mine and this is what it says.


I have done steps 1-3, pulled no relevant codes and lights still do not work. I'm not sure what step 4 means when it says inoperative lamp power supply? Would that be the dimmer switch?

 

Step 4 is a wiring problem. This would mean a wire from the fuse panel to the light or from a ground to the light is bad somewhere and needs fixed.

Actually, if I follow the chart correctly, you are not even looking at step #4.
Step 1 - Yes; go to step 2
Step 2 - No; go to step 3
Step 3 - No (all lamps are failing); go to step 5

Step 5 is mentioning to replace the BCM. Which, it could be the BCM. I would like to go one step further before doing that. Check the wiring diagrams to verify if what I am going to suggest is possible. I believe MOST of the time the BCM triggers a relay. If so, you should be able to remove the relay and jumper the connection to bypass the relay and temporarily force the lights to activate without use of the BCM. If I am right and the BCM is only triggering a relay AND you do that test and the lights do activate, the next item I would check is if you have continuity from the relay to the BCM.....
If I am wrong, perhaps the diagrams can present another test that is worth while.

 

These wiring diagrams always confuse me, but I found this in the book. I'm not currently at home but when I go back, I'll check it out some more, this was a picture from last night at 2 am.

 

I just did some additional research based on that schematic. Here is what I can tell you about that schematics.circuit 1037 come from the BCM is a data line, nothing more. That box in the diagram talking about a DLC, that is sometimes called a "splice pack". A bunch of data connections connect there (the car network in these cars is so simple, you could wire nut the wires together because it is just a bunch of "broadcast" traffic). So, from that splice pack is a data link to the radio and a data link to the cluster.

Now that we know ALL of that is "data" (not a power or ground circuit, not a trigger for a relay), we can start ruling things out.
- The cluster has (to my knowledge) has only ONE data wire. If that wire is not longer communicating with the car network, many of your gauges would not work (such as no speed or tach). You would also have a trouble code for the cluster being disconnected.
- I know from other things I have done, the radio has two data connections, but GM is only using one (I hi-jacked the other as a pass through, long story, I can point you to a post if you to a thread I made that info was part of it if you are interested). If the radio was not talking with the car network, there are problems it would have there. I am not sure which features are tied to that, but if the radio is working as expected, pretty safe to say this connection is good. Also, if you have XM and the XM receiver is responding to the radio, I can confirm, things are working as expected.

Now, both the cluster and the radio use circuit 8 labeled "Instrument Panel Lamp Supply Voltage - 1". On the connectors, for the cluster is it a gray wire in pin B1 and the radio it is a gray wire in B4. The BCM Pink Connector, pin B11 is also a gray wire, part of this circuit 8. I have ran out of time to research that. The name seems to imply it is a circuit specific for lighting only. If so, the next step I would believe is to get a schematic that validates what it does/how it works and then understand if it is possibly part of the problem and then determine how to test to see if it it or is not the problem.

 

Thank you a ton for the help Maniac, but in the past couple of days, my backlighting has worked flawlessly during the night all of a sudden. Do you think this could have been from me removing the dash cover that my brother previously had on it? It fully covered the ambient light sensor but when I took it off, the dash lights still didn't work at night for a while up until about three days ago. Could this have been the car adjusting to a new sensor and headlamp switch along with me removing the dash cover? I want to make sure before I declare this solution as solved, as I would hate for this issue to arrive in the future again.

 

Odd that removing the cover did not immediately resolve this. I suppose anything is possible. See if it keeps working and if so, perhaps that was it.