I think my body control module is causing a battery drain

[RofC]

I've read through quite a few battery drain topics on here but none seemed to have my specific issues/symptoms.

 

I bought my '06 SSS a couple of weeks ago, it had sat for about 8 months. I was aware of a power drain issue taking 2-3 days to flatten out the battery. The only symptoms initially were the radio, clock & instrument cluster lights staying on after turning off the engine & opening the door along with the battery light coming on. After doing my initial fill-up, the 4 gauge cluster group read high, battery gauge was jumping & hitting 19v, speedo, tacho & tranny temp were ok.

 

Two days ago I drove it to work, 8 hours later the battery was dead. Got a boost, the gauges reset correctly but the other symptoms persisted...

 

There's also an aftermarket subwoofer/kicker/amp setup along with a cd changer, the woofer doesn't woof & the radio Aux function won't switch to the cd changer. Could be an entirely unrelated issue though... aftermarket amp power is disconnected for now 

 

I did a parasitic power draw test with a multimeter, had a major drain from the radio and smaller ones from the amp, onstar (info fuse), IPD/DIC & IGNE circuits. 23 amps total.

 

I took apart the dash, center console & bottom door trim, inspected all the aftermarket wiring for the amp/kicker and the cd changer (seemed güd), the only wire i didn't trace all the way back was a brown one coming from the cd changer & heading up to the steering column along the main aftermarket amp power wire.

 

Then I took out the instrument cluster & radio, disconnected them and plugged everything back in. Went to do another parasitic power draw test in case it was caused by a bad connection I had shaken up... no more power drain! It read 1.3 amps for 5 minutes, dropped to .08 for a few seconds then went to zero.

 

Connected the battery, started it, no battery light in dash, gauges reading true. Turned it off, opened the door & the radio turned off along with the dash lights.

 

So logically here, bad behavior (radio, cluster lights staying on, gauges suddenly to the right) - partially reset by a drained battery (gauges reset) + sudden instant power drain involving radio, amp, onstar & DIC circuits - corrected by wire wiggling & hours long battery disconnect.

 

Does this point to a bad BCM or am I just dealing with a bunch of separate gremlins & got lucky today?

 

I'll try and get a scan done this week, see if any bcm codes pop up (apparently none might even if?!).

Edited December 13, 2021 by RofC (see edit history)

[RofC]

So I had the following codes that came up:

 

P0455

Probably my evap canister, the pump was clicking off every 2-3 gallons on my first fill up, now just once in a while when I start filling. I had the loose/leaky fuel cap message from the DIC yesterday.

 

P0650

Possible malfunction indicator lamp issue or bad ECM.

 

P0654

Instrument cluster issue or bad PCM.

 

B1440

Ignition switch issue or bad BCM.

 

B2600

Faulty Left Park/Daytime Running Lamp issue or bad BCM.

 

B2610

Headlamp And Panel Dimmer Switch or bad BCM.

 

U1000

Was related to the instrument cluster, communication fault with the module.

 

Going forward, I'll do a ground connection check everywhere I can and unplug/plug every connector, might as well start there and see if codes come back. The P0650 is bugging me because i never saw the CEL light up, just the battery light. Cluster related?

 

The cluster has never been refurbished so I feel like doing it myself. I just hope sourcing all the bits besides LEDs & steppers ain't a pia.

 

Having 3 codes with a possible bad BCM as the cause makes me think it might still be the main issue. 

 

I'll update as things progress.