TBC fuse parasitic draw

[Bjbmacon]

Hey guys! New here. Thanks for the add to the forum.

I have a 00 Tahoe that I’m getting a draw on the tbc fuse in the under hood fuse box. It’s enough to kill battery in about 2 days. The draw is around .83. I have pulled everything I can think off to stop the draw and nothing stops it. I have pulled ecm,bcm,cluster,radio,hvac controls,on-star modules,light switch,seats,airbag,all rear hvac actuators and blower module. I know that looking on Mitchell wiring diagrams that fuse has 4 circuits. Bcm, keyless antenna receiver and the light switch plus the high low switch. The keyless receiver was missing when I got the truck. I’ve disconnected all other sources. Any help would be highly appreciated!

 

[MassHoe04]

A few other GM truck forums had people looking at ignition switch as possible source. They described a 0.8 draw on the TBC fuse while this was happening.

2000 NBS Tahoe dies overnight..Narrowed down to TBC fuse

I had a problem a few months ago about the truck dying and thought it was from the radio and seo1 fuse. I fixed that problem (i think) and I now have a battery drain again. Using the amp clamp, im getting .8-1 amps draw..i do not get a reduced draw when I remove the radio and seo1 fuse, but only...

www.gmfullsize.com

Our resident electrical experts can help walk through your issue...
I am sure you will get directed to search up "Parasitic draw" threads on our forum, since you are not the only person to see this kind of thing.
Do check those threads out. There are a lot of great step-by-steps on what to look for in diagnosing electrical draw issues.

Also suggest checking for the "usual suspects" (or at least rule them out): main ground points to engine block and on the body mount (under the driver's side door), battery cables, battery connections, etc.
Inspect, clean and tighten all ground connections. Bad grounds can prevent the BCM from shutting things down completely and stay in "sleep mode", drawing power on things like radios or HVAC controls. BCM is supposed to exit sleep mode and completely shut shings down after the programmed time of inactivity. Bad ground can prevent that shutdown from happening.

Check connectors at the BCM and wires you can see along your various harnesses. Maybe a low volt wire grounding out. Not enough to blow fuse. Could be a wire from the BCM to another component that draws low amps. Not enough for a fuse to blow, but enough to draw power.

Just some thoughts. Look for anything obvious at least...

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[Bjbmacon]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[MassHoe04]

Nice! Running dual pipes out both sides?

 

[rockola1971]

Pull connectors on BCM and then reattach when you are ready to drive 24hrs or overnight later. Might have a bad BCM or its just going to sleep then its grounds for you. Check for corrosion, broken wire or the growing green suff on ground at rear of engine to firewall AND also check the bundle of grounds on drivers side chassis under driver door up near where the firewall starts. Wouldn't hurt to go ahead an remove bolt and wire brush chassis point, bolt and terminal lug on wires.