Ign B 50 Amp Fuse / Circuit parasitic draw

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hekg

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Hi all, I've been dealing with a parasitic draw for a very long time and I have finally narrowed it down to the 50a ignition B fuse under the hood.

When I unplug that fuse I read a steady .050 milliamp draw which is perfect.

Also, when I plug that puse back in the amp draw jumps non-stop between 0.079 and 0.150. It never settles down on one number and just continuously jumps between that range.

Does anybody know where on this circuit I should be looking for the problem? What can possibly be drawing that kind of unsteady amperage on this circuit?
 

hekg

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Have you started to pull out individual small amperage fuses to see what affects your reading?

Yes I tested all of the fuses under the hood and inside the cabin and only the 50a ignition fuse showed an amp drop when removed.
 

AK49BWL

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Does your Tahoe have the Body Control Module? If it does, THAT is definitely your draw source. The BCM keeps the Courtesy Power Relay active for 15 minutes of inactivity before shutting down. The 50A Ign fuse runs straight to it, and the ignition switch.

What you can do to check if the problem is the BCM, is unplug it. It has three connectors, you only need to unplug the black 6-pin.

As for where the BCM IS in the Tahoe? .....I actually don't know lol. In the Escalade and Yukon Denali, it's under the center console with the Bose amp.
 
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hekg

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Does your Tahoe have the Body Control Module? If it does, THAT is definitely your draw source. The BCM keeps the Courtesy Power Relay active for 15 minutes of inactivity before shutting down. The 50A Ign fuse runs straight to it, and the ignition switch.

What you can do to check if the problem is the BCM, is unplug it. It has three connectors, you only need to unplug the black 6-pin.

As for where the BCM IS in the Tahoe? .....I actually don't know lol. In the Escalade and Yukon Denali, it's under the center console with the Bose amp.

Interesting ... I honestly do not know if mine has a BCM but I'll look into that. thanks
 

AK49BWL

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Easy to tell: look at your convenience center. If you don't have the black vertical rectangle box on it, you have a BCM.

Another way, if your truck goes ding ding ding rather than the solid tone when you open the door with the key in or lights on.

Yet another, if the radio stays on when you turn the truck off (retained accessory power).
 
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