Auto Electrical Forum

Automotive Electrical Tech Tips and Questions Answered

Question:

BASICALLY, I HAVE A PROBLEM WITH THE INSTRUMENT CLUSTER REACTIVATING AFTER EVERYTHING IS TURNED OFF (2003 CHEVY S-10). TURN OFF THE ENGINE AND THE GAUGES TURN OFF, BUT 15 SECONDS LATER THEY REACTIVATE TO SOME “DEFAULT SETTING. THE TEMP GAUGE GOES TO 230 REGARDLESS OF ENGINE TEMP. THE FUEL GAUGE GOES TO ½ FULL REGARDLESS OF HOW MUCH FUEL I HAVE. THE OIL PRESSURE AND AMMETER GAUGES WILL TWITCH. REMOVING THE KEY WILL DEACTIVATE THESE FALSE READINGS, BUT 15 SECONDS LATER EVERYTHING REACTIVATES. OPENING THE DOOR WILL ALSO DEACTIVATE THINGS, BUT CLOSING THE DOOR WILL REACTIVATE THE GAUGES AFTER 15 SECONDS. IF I LEAVE THE DOOR OPEN, NOTHING REACTIVATES. I HAVE NEVER HEARD OF A SHORT WITH A 15 SECOND DELAY, BUT OVER TIME MY BATTERY DOES DRAIN.
WHAT IS GOING ON?

Answer:

This is a great questions because it gives me a chance to make a very good point, which is some times it is best to bite the bullet and pay the dealer for an hour labor. But let’s look at the problem first. The likely problems here are as follows, 1) Body Control Module (BCM), 2) key switch or 3) you have added an aftermarket alarm/remote start and it has a problem.

You have 2 choices for the BCM, first unhook the battery for about an hour, I know that most manuals say 5 minutes but lets just make sure the BCM resets. If resetting the BCM fixes your problem you will need to replace the BCM because it is probably a glitch in the system and it will probably start doing it again. Second choice is take it to the dealer and have them test it, the sad fact is the auto parts store and inexpensive OBD scan tools will not read or program the BCM, also it is important to note that if you need to replace the BCM it will need to be flashed by the dealer.

You could have a problem with the key switch, but I don’t think so, I would start with the BCM and the dealer can easily tell if it is the BCM or the key switch.

The alarm is easy to diagnose, if you have one look under the dash, look up near your foot pedals. You are looking for a black box (brain) which has several wires leading from it, about 2″ to 5″ our from the brain you will find some fuses, if the harness is taped find a square part of the tape, remove the tape and you will see the fuses, remove all fuses and see if it fixes your problem. If so you will need to consult a local stereo shop.

If you have bought this as a used vehicle you may have an alarm without knowing it, some times they are just left installed and “dormant” this is a bad idea because if the alarm fails it can result in the problems you are describing. If you don’t want an alarm or want to have it removed it is ok to leave it installed with the fuses removed, however some alarms interface with the key switch wiring preventing it from starting with the fuses installed, if this is the case with yours, then install the fuses and drive it to your local stereo shop and have them remove the alarm.

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