SOLVED! Battery Drain related to Passenger Front Door Module

[Street]

So, I've been chasing this one for as long as I've owned the Envoy (about 1.5 years now).

Problem: After any given random(but often) night, the battery will be dead enough that no lights, no remote locks, clock resets, etc etc. HOWEVER! Disconnecting the passenger front door module (yep, the window&lock switches) stops all that drain. Of course, I loose the use of the window, power mirror, and locks for that door; but at least she starts up in the morning, every time.

What I've tried:
Purchased, (2 now) replacement modules; they work for a month or two and just stop, no window, no locks, no mirror - but no battery drain. I swap back in the factory module, and I get all that working again; but I can't leave it like that because I can't have a dead battery every morning (or nearly every morning - it is a bit random, but leaving me without my only transportation isn't an option -- I'm sure you understand).
Currently, the factory module is in the door, but the connectors are unplugged and I haven't had a dead battery since.

So, next block on the circuit diagram is the BCM; I found one online from a takeoff on a same equipment truck. I haven't had a chance to test it long term as I just learned about the 30 security learn override procedure (thanks Mooseman and TJBaker57). I'm hoping that it was a problem with the BCM not putting the module to sleep reliably or the like.

There you have it @TJBaker57 that's the story on my passenger door module and battery drain.

 

[azswiss]

Question: does remote keyless entry still work? I ask because when monitoring the system bus during remote keyless entry I observed traffic involving the passenger door module but not the driver door module.

 

[Street]

Yes, keyless entry works. Can't lock or unlock RF door, but that is what part of the module is supposed to do.

 

[Mooseman]

Where did the replacement door modules come from? New? Used? Same year?

 

[TJBaker57]

Ok then! Let me toss out a thought or two.

The BCM is responsible for announcing the status of the network. However, it does not send messages to a specific module address.

In a normal shutdown situation you turn the truck off and remove the key. We can see that several modules continue operations like the radio keeps playing and so on. When you open the door the door module senses the door ajar switch activation and announces this on the vehicle network. The BCM sees this and acknowledges this message and then sends out a message that is addressed to "network control" and all modules listen for these messages from the BCM. This message should be seen by every module, like firing a flare gun into the night sky. It's not addressed to any particular module/person, but all can see it. Within the message are details of the status of the vehicle network like if the key is on and what position it is in etc. I believe the modules react to this message.

So if the BCM were not sending out this message things like the radio would keep right on playing when you opened the door.

I think some modules time out like the radio will stop eventually if you just sit there and don't open the door.

Question: does remote keyless entry still work? I ask because when monitoring the system bus during remote keyless entry I observed traffic involving the passenger door module but not the driver door module

That is not how it should be! However it can be terribly confusing just looking at the raw data stream.

Here is another thought. If either the power or ground that feeds the PDM were unstable that could cause the module to wake, sleep, wake, sleep, wake. Just a thought.

 

[azswiss]

That is not how it should be! However it can be terribly confusing just looking at the raw data stream.

Glad to get your thoughts on that, had me stumped as to why.

 

[TJBaker57]

Glad to get your thoughts on that, had me stumped as to why.

Perhaps I can resurrect my thread on ELM327 and class 2 data using this example !!

 

[JerryIrons]

So it seems to me that you've got a parasitic draw in that system somehow, and it's not the passenger door module. Assuming when you put a new one in, it wasn't an older version that was part of a recall. (my 06 trailblazer had recalls on those)

So something is still drawing power. Window motor? Door lock? Maybe you can try unplugging those specific items one at a time to narrow things down?

Or there is a short in one of the wires causing it, and the circuit is only complete when the module is in place.

If it were my vehicle I'd use a meter downstream from the door module seeing if volts are flowing after lights go out inside the vehicle. Do things like unplug window motor for a bit. gonna be a process of elimination I think, just be prepared again for dead battery.

 

[Street]

Hi Everyone,

I thought I would give an update on this problem. Finally located the draw to a specific module -- the Passenger Front Door module. After being replaced several times by "newer" part numbers, which would work for about a month or so then stop; I found on e-bay the exact same part as a working take-off. This has *FINALLY* solved the battery drain and, combined with the a new ignition switch module, a new battery(at least one bad cell), and a new alternator(it was running wide open 14.9V all the time), the ol'Envoy can finally stay parked overnight without killing the battery.

Thanks again for the all the advise; which lead me to fixing these issues.