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Dan, ASE Certified Technician
Category: Chevy
Satisfied Customers: 2270
Experience:  20 Year Factory Trained Current GM Technician
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2003 Silverado 1500: headlight..the highbeam indicator (blue)

Resolved Question:

I have a 2003 Silverado 1500 with the Automatic headlight function. Lately the highbeam indicator (blue) stays lit in the dash even though everything is off (engine off, key out, all lights off, etc.). It usually comes on about 10 seconds after the dome light goes out (after closing the door). If the parking or lo beam headlightlight is turned on, that high beam indicator does go out, such as when driving. Same if the high beam stalk is actuated. If you are sitting in the truck with everything off, when the high beam light comes on, actuating on and off any light will make it go out, but it will come back on after about 10 seconds. Is this a previously observed behaviour? Idea on what could be the cause? Thanks, John.
Submitted: 6 years ago.
Category: Chevy
Expert:  Dan replied 6 years ago.
I have not seen this on a silverado but I have seen it on the trailblazers a few times. I replaced the cluster to fix those.
The BCM ( Body Control Module ) controls the on and off function of the high beam indicator through the serial data circuit so there is nothing to check with a volt meter.
If you had a scan tool, you could check the data in the cluster to make sure nothing is commanded on. but it sounds like an internal fault in the cluster.
Customer: replied 6 years ago.
I have an OBD2 scanner. Is that likely to be able to check data in the cluster? My understanding is that body codes are not available from this scanner. Is there anything to try to help determine the cluster is defective other than purchase a replacement?
Expert:  Dan replied 6 years ago.
You would need a scanner that cost over 2K to read this data.
The only other thing you can do to make for sure is to unhook the BCM connectors and see if it comes on.
Customer: replied 6 years ago.
So the cluster must remain connected (powered)? Is there a discrete wire from the BCM to the cluster for the high beam indicator, or is there a data stream from the BCM to the cluster for all the indicator lights and gauges? If a data stream, how would disconnecting the BCM cable make the high beam indiator come on? It seems it could just as readily go off? If the high beam indicator is controlled by a discrete wire from the BCM, can you tell me what color wire or pin # XXXXX the cluster connector? Would the high beam indicator wire be grounded by the BCM or taken high (+12v) by the BCM to make the light come on?
Expert:  Dan replied 6 years ago.
No wire. Just a data line that all the modules use to talk back and forth. No way to check.
Disconnecting the BCM will get it off the data line to tell if it is sending a signal to the cluster to keep the light on, I don't think this would be the issue because this would keep the BCM awake and run the battery down overnight.
Customer: replied 6 years ago.
OK. Understand the cluster is controlled by a data line to/from the BCM. However, I don't understand the last sentence. Recall the battery does not run down with the high beam indicator lit for well over a week. I don't know how much longer it could go. Do you mean you doubt the problem is in the BCM, and is most likely in the cluster? I believe you do. Again, I'm looking for a way to verify that other than by replacement. I recently had the cluster gauges and bulbs replaced due to a couple of stuck gauges. They had some sort of in-house developed tester. I guess it's worth a call to them to see if they can command the high beam indicator on and off, and see what it does. Your thoughts?
Expert:  Dan replied 6 years ago.
If the BCM was keeping the light lite up on the cluster, the BCM would stay awake and they draw around 400-600 milli amps which will run the battery down in about 15 hours.
Yes, they has a policy on these clusters for the gages. If it was done within the last 12 months, they could warranty it for you.
I believe the issue is in the cluster and not the BCM. The only way to find out is with the BCM unpluged.
BCM is easy to get to. right under the steering column. has about 4 connectors to it.
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