Just replaced the alternator and battery. Now looking for short. If I pull fuse #6 in the engine compartment fuse box the short goes away.

 

Ok, thanks. Hmm. Where to start? One guy said he had experienced a short in the circuit under the drivers seat. I may start there. We adjust the seat a lot. Wife short, me tall.

 

Per the repair manual, fuse #6 in the engine compartment is a "Hot all time" feed to the BCM.
I would replace that fuse then start pulling the BCM fuses and relays one at a time until you find the one that is shorting or drawing power. This should narrow it down to which component it is instead of just something in the BCM.

Fwiw. You stated if you pulled the fuse the short "goes away". Exactly what do you mean by this.

 

How are you testing this draw on the battery?

 

I connected a 12 volt test light between the negative battery terminal and ground. The light comes on when Fuse #6 is in and goes off when fuse is pulled.

 

That is a "dead" short. There is a wire somewhere touching ground.

 

Put an ammeter there to see how much current it's drawing. As you see in the previous posts, the bcm supplies power to some things for 10 minutes, others for 20 minutes so you would have to wait at least 20 minutes after you put the fuse in and even then, the BCM itself will draw a slight amount of current.

 

As don06 states the bcm takes awhile to go to sleep after the key is tired off. The test light test will only be a good test if you connect it after the key is turned off for about 20 min and is hooked up with out disconnecting battery power.

Once the battery is disconnected and hooked back up the bcm will wake up and you would have to wait until it go's back to sleep for a draw test.

As stated above an inductive ammeter is best to test for a draw so as the battery don't have to be disconnected.

Here is a tsb that may help explain more. It's not for your year of car but the electronics are about hhr same.

Pic4108G
#PIC4108G: Battery Draw From The BCM 2 Fuse - (May 11, 2009)


Subject: Battery Draw From The BCM 2 Fuse


Models: 2005-2009 Chevrolet Cobalt

2006-2009 Chevrolet HHR

2007-2009 Pontiac G5
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This PI was superseded to correct module reference. Please discard PIC4108F.
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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Customers may report a battery drain on their vehicle. Upon inspection technicians may see a battery draw of 100-170 mA on the battery. Typically when the BCM 2 fuse in the UBEC is pulled, the draw goes away. When looking at the wiring schematics you will NOT see the microprocessor (inside the BCM) that is powered by this fuse. This Microprocessor is sending small amounts of voltage out on the door lock input circuit #682 (White, BCM X1 pin 7) and the dome lamp output circuit #149 (D-BU/WHT, BCM X3 pin A3), Either of these circuits could be pulled low and will cause this condition.

Recommendation/Instructions:
Install the Tech-2/Candi module and look at the door lock switch status in the BCM data section. Status should be reading "Idle". If it reads Unlock or Lock, then check for a possible short to ground in circuit #682 (White) or a possible door lock switch concern. If those check out OK then remove circuit #149 from the BCM and wait to see if your draw times out in 20 minutes. If it does then check for a STG in circuit #149 (D-BU/WHT).

 

Is that fuse #6 a 40 amp fuse? If so according to my 2011 schematics it goes to the BCM on a Red/Black wire which is the B+ for the BCM but also to fuses inside the BCM - fuse #8 (ign switch for key in cylinder), fuse # 10 (HVAC - hvac control assembly and theft deterrent module), fuse #7 (Cluster - DIC and instrument panel) fuse #9 (Stop lamp CHMSL relay), fuse # 6 (AMP audio amplifier). This is a lot of stuff. I would do what firemangeorge said about pulling BCM fuses to help eliminate some of these circuits. You will probably need to get the service manual and wiring diagrams to follow all of this. If not then a shop visit is in order.

 

Thanks to everyone who gave me feedback. Testing for a short with a light I think led me astray. After I replaced the alternator which had a burnt out diode and the battery that wouldn't take a charge, I started the car and everything seems fine. Battery is staying charged. Thanks again. Now I need to work on my old Nissan Stanza Wagon.