"Security" light stays on

[kaspr]

My problem: the "security" MIL light stays on whenever the key is in the "run" position. It is supposed to bulb test for 5 seconds and then shut off.

I followed my factory service manual and narrowed it down.

It turns out the Pass-Key II system (VATS) is fine. What is causing the light to be on is the Retained Accessory Power (RAP) module. This has to do with the car alarm. (I unplugged the Pass-Key II module and the problem persists). However, I followed the tests for the car alarm system, and all tests were passed (and the security light functions properly during all functions). The alarm is functioning fine. But for some reason, the RAP module is closing the ground circuit going to the "security" light whenever the key is in the "run" or "start" position. This just started happening 2 days ago, and is happening consistently - not intermittent.

Unfortunately, the service manual doesn't say what to do if the light stays on and if you've narrowed it down to the RAP module (which I have). Would I need to replace the RAP module, or could it be that the RAP module is receiving an input that is causing it to leave the security light on? I can say that the "security" light operates correctly in all other situations other than when the key is in the run or start position.

[HotZ28]

IIRC, PASSKey II is integrated into the BCM which sends a Class 2 serial data signal that controls the security light. I would think the BCM may be grounding the RAP module, if it is actually a sepeate module.

[kaspr]

Originally Posted by HotZ28

IIRC, PASSKey II is integrated into the BCM which sends a Class 2 serial data signal that controls the security light. I would think the BCM may be grounding the RAP module, if it is actually a sepeate module.

The security light can be grounded (and thus illuminated) by either of 2 independent modules: the PASSKey II module or the RAP module. Either one can ground the circuit. I confirmed that it's the RAP module that is doing it because when I unplug Connector C3 on the RAP module (which contains the circuit for the security light), the security light operates normally as per the PASSKey II module. When I plug in the RAP module, it grounds the circuit whenever the key is on run or start. Perhaps the RAP is part of the BCM, as you said. So the big question is.......... what should I do to figure this out? Is it a faulty RAP or might it be some sensor or BCM that is telling the RAP to turn on the security light? But keep in mind that all vehicle alarm tests were positive. I guess I don't understand quite how the BCM plays into it, and what I might do to diagnose this problem further. Any suggestions?

[kaspr]

One other thing I noticed. It seems that some of the time, the "security" light is going off after 1 minute. But then if I shut the car off and re-start, it will come back on and stay on for 1 minute. Some of the time, it has seemed to stay on for much longer than 1 minute, though. I wonder what would cause the light to come on and then eventually decide to shut the car off? Once again, I confirmed that the VATS (PassKey II) is not what is turning the light on, and I also confirmed that the car alarm is functioning fine (I did all of the tests listed in the GM manual.

[HotZ28]

I know you don't want to here this, but it may be worthwhile to have a Tech II scan to see where the problem is. It sure sounds like a BCM problem.