NEED HELP Odd battery drain

[Photoguy_15]

I'm having a strange issue with my '02 Bravada. If I have to move it a short distance (for example letting my roommates out of the driveway when the Bravada is at the very end), and shut it off, it'll be dead in under 8 hours.

Couple details if they help.

- The problem started after hooking up a harness that I found disconnected under the center console, while troubleshooting why my rear speakers weren't functioning

- The truck had an aftermarket remote start, which I disabled (Removed the control box)

- After searching Google, I found out that the rear HVAC control unit can cause a draw and subsequently removed it, but I still have the issue

- The battery is new, and the alternator is working (shows 13.8-14v on my volt meter)


Everything is fine if I drive the Bravada for a while, but there are occasions where a quick get-a-way is necessary to avoid a potentially dangerous situation; and having a dead battery in the middle of nowhere sitting a couple hours could be disastrous.

 

[Sparky]

What if you unhook that harness again?
Can you grab a pic of it?

 

[Blckshdw]

- The battery is new, and the alternator is working (shows 13.8-14v on my volt meter)

You should be seeing about 14.4V when the engine is running. If you're consistently seeing sub 14V, I'd say get your alternator tested.

Have you done any testing to see how much parasitic draw you have? Or at least disconnect the mega fuse under the hood, or the rear fuse block power supply to see if your battery doesn't die over night? Gotta try and whittle down the source of the draw.

 

[gmcman]

Do you also have an aftermarket stereo? If not, do you have the Bose system? If aftermarket check to see if you have an additional amp and see if the signal wire is connected to keep the amp turned on all the time.

I agree that sub 14V readings should raise a brow, but 13.8 is within the parameters but on the low side and may or may not keep the battery charged. I would chase that harness you plugged in as well as monitor amp draw with a capable meter from the battery while pulling fuses.

Does your keyfob open the doors when that harness is unplugged, what about the rear wiper? I don't know for sure but isn't there a module in the rear liftgate that may cause an issue if the keyfob didn't work?

 

[Photoguy_15]

What if you unhook that harness again?
Can you grab a pic of it?

It's the harness for the rear HVAC, it's a pain to disassemble the console just to get to it. lol

You should be seeing about 14.4V when the engine is running. If you're consistently seeing sub 14V, I'd say get your alternator tested.

Have you done any testing to see how much parasitic draw you have? Or at least disconnect the mega fuse under the hood, or the rear fuse block power supply to see if your battery doesn't die over night? Gotta try and whittle down the source of the draw.

It wasn't a consistent sub 14v since I only checked it once, but I should check it after driving the truck. I mark it down to having been right after boosting the truck.

Do you also have an aftermarket stereo? If not, do you have the Bose system? If aftermarket check to see if you have an additional amp and see if the signal wire is connected to keep the amp turned on all the time.

I agree that sub 14V readings should raise a brow, but 13.8 is within the parameters but on the low side and may or may not keep the battery charged. I would chase that harness you plugged in as well as monitor amp draw with a capable meter from the battery while pulling fuses.

Does your keyfob open the doors when that harness is unplugged, what about the rear wiper? I don't know for sure but isn't there a module in the rear liftgate that may cause an issue if the keyfob didn't work?

Stock stereo (Non Bose), though I'm wondering if it did have an aftermarket stereo at one point. Everything except the rear speakers and rear HVAC unit work without that harness plugged in. Though when I unplugged the HVAC unit itself, the instant economy quit working on the DIC.

If I could somehow bypass that rear HVAC unit, and still have the rear speakers work, I'd just do that.

 

[Photoguy_15]

Figured out where the drain is coming from. It is the rear HVAC unit, I left it unplugged overnight, and it started fine this morning.