2000 Bonneville - Tricky Parasite Drain
2000 Bonneville, been running fine, until battery drained dead over a weekend of no use. Everything seems to be working correctly, just have some parasite drain. Traced out the drain with amp meter and patience (disconnected just about EVERYTHING once) and discovered that if I cycle the ignition and wait 20-30 minutes for the timers to shut things down, I'll see a residual load of about 0.512 amps indefinitely. If I don't cycle the ignition switch and just open/close the doors, I can watch the timers drop the 5.0 amp draw from the lights down to about 0.143 amps and down to 0.007 amps (perfectly acceptable) after about 3 minutes (lowest delay setting). If I cycle the ignition, and see this 0.512 amp draw after 30-45 minutes, I can pull the "PCM BATT" fuse and watch the load drop immediately down to the 0.143 level, and then a few seconds later down to the 0.32 and 0.007 level. Something in the PCM BATT circuit is sticking on after a cycle of the ignition. Looks to me like the PCM isn't shutting down?
I removed the PCM and looked for the obvious, but didn't see anything. My real question is where is the "timer" to shut down the PCM? Is it possibly the PCM itself, or somewhere else like the front BCM? What shuts off the PCM?