I was re routing power wires in GM in hopes to have the rain sensor powered while the car was locked and armed, to have the rain sensor detect rain and close sun roof if left open by accident. The idea worked, if the car was left with roof open, ignition off but not locked - water on windshield would close the roof on sleeping car. The moment the car was locked the cluster lights would come on, no other lights, and the rain sensor did not react to water. In other words, it was fail, but showed me an example the rerouted electrical path can have unpredictable consequences.

Terminator,

But doesn't the fact completely cutting off power to the GM by removing its connectors resulted in the elimination of the huge parasitic current draw implicate the GM itself? I didn't get that result when I disconnected the connectors to the hatch lights (or any of the other interior lights). I guess I'll find out when I get my new GM - that will be an anxious moment when I run a test of the parasitic current draw after plugging it in.

Just the same, I'll look for chafed wires, but I'm not quite following where the wires you're referring to are located. Could you please elaborate? Are they inside the liftgate, or somewhere else? What all do I have to remove, if anything, to get to them? Thanks.

I am not saying that GM is ruled out - it is still in the game. I usually try to go from simple to more complicated, and replacing a module while is a simple procedure, rather on an expensive side of spectrum in comparison to checking the wiring. Since you already checked the wires, GM could be the next natural step. I am curious to see how this drain will be resolved, so keep us posted, please.

There are two rubber boots, between main car body and upper liftgate. The right boot has wires, the wiper motor, the lic plate lights, the gate button, the lights... since that area is always bending, it is prone to chaffing. Pry the boot from either end, and inspect the wires using strong light, so you don't miss small nicks... the left boot has a water hose for rear wiper and it could have a wire or two, i just don't remember off the top of my head. Let's hope there is no chaffed wire, as proper repair can be a bitch...

Crap! New (actually $50 from eBay) GM installed, and no change - still getting over 4 amps of current draw. This is getting old to the power of ten. To recap, here's everything I've done to track down this current drain:

- Indicates 4 amp current drain when the car is at rest and all fuses are connected. Causes battery to go dead in a couple of days.
- Pulling fuse 27 brings the current drain down to the specified 38 mA after letting the car go to sleep mode
- Pulled all the other fuses, with no change to the 4A current drain from any of them
- Fuse 27 protects the glove box light, interior lighting, and windshield washer system
- Disconnected windshield washer pump connector - no change
- Disconnected both rear hatch light connectors - no change
- Disconnected both dome light connectors - no change
- Disconnected the connector to every single interior light in the car, including the glove box, footwells, doors, etc., one by one - no change
- Disconnected all three LCM connectors sequentially - no change
- Disconnected connector to radiator fan switch (before I discovered fuse 27's effect) - no change
- Removed rubber boots protecting the wiring going into the rear hatch to check for signs of damage or chafing - all wires are in perfect condition
- Disconnected all the connectors to that little box at the base of the window in the rear hatch lid under the piece of plastic trim the runs the width of the lid (thinking one of these might send power to the rear window washer, in case this was also protected by fuse 27) - no change
- Noticed that when I reconnected fuse 27, the rear air spring pump turns on, so, thinking the pump may be drawing current when the car is off, I disconnected the connector going to the pump’s motor – no change.
- And now, replaced the General Module with a new one - no change

I'm about to punt on this thing, but I can't think of a good way to do that. I had a parasitic leak years ago that I traced to somewhere in the stereo, so I rigged up a relay that was energized by a source of +12V I found near the offending fuse when the key was turned to the accessory position, and that has done a great job of killing that leak. But I can't do that for this problem, because I need the interior lights to come on when I open a door, not when I turn the key. So first, does anyone have any other ideas of things I can try? If not, is there a convenient way to band-aid this thing to allow fuse 27 to be disconnected when the vehicle is at rest, and become connected when I open a door or the rear hatch? And what about the air spring pump? Is it safe to drive the car with this pump not working? I’m getting an error message saying the self-leveling system isn’t working when I have fuse 27 removed. Thanks.

4 amp draw. Wow that is a lot. Is the 4 amp level continuous?
Might not be since you mention kills battery in a couple of days (100AH batt / 4 amp = ~24hrs). Not to pick at your theory so far but just wanted to offer that maybe the load comes and goes?

My guesses came to air system around #27 fuse; could it be valve block or something besides the pump. If you leave #27 disconnected does your suspension sag over time?

GLuck, hope something jumps up soon.

there is still "unauthorized" power path somewhere in the circuitry. As trader said, the INPA might be able to point in the right direction as some modules will report a blown transistor but with the GM replaced and no change, along with all the other things that have been done it natural to suspect that there is still some short somewhere...


You have ID'd part of the problem, and now you need to further narrow it down and not give up - -taking the car to a dealer can prove super expensive, as with this type of problem you are writing them a blank check...

Once fuse 27 is in place, you get draw... when it is out - no draw. Fuse has 2 legs (duh!! lol) so, when you reconnect the fuse back, something to the left or to the right of the fuse is shorting. one of the legs of F27 goes to one of the master fuses - that end is also connected to a number of other fuses and if that part of the leg was shorting, you would see the draw... So, the chances are, the short is downstream from the F27. You have disconnected the end points that the F27 is feeding to, and you still have the draw. It means that the electrical "bridge" that draws current is still between the F27 and the end "consumer"...

To trace that, we need to figure out if there are any "intermediate" connectors between F27 and any of its "consumers", so you can disconnect those connectors and see what happens to the draw AND we need to figure out where those wires can be "exposed" to sharp edges... One of the spots is under the rear seat, on the right side, where the wires transverse over a sharp edge of the body going from the trunk into the carpet.

It is relatively easy to check, much easier than the trunk lid boots - you pull the rear bench up, pull the foamy insert that is on the right side and inspect the wires. The whole process, with bench out, inspection and bench back in should take about 15-20 minutes... Give it try, and then we move on further...