Power Drain

[PolyMatt]

I have a 99 Tahoe, 4wd, 5.7 with a battery drain issue. I traced it to the 50 amp fuse labeled as “lighting” under the hood. Appears to be a 4 amp draw. Any suggestions on what it could be?


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[east302]

Here is the diagram for a 98, it’s probably the same for the 99. I’d pull the downstream fuses in the interior fuse block to see what stops the drain.

It looks like it is the cigarette lighter, security, radio, etc. Note that the headlamp switch is not on a separate fuse, unplug it from the back to isolate it.

Do your low beam headlights work?

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[PolyMatt]

Thanks for the diagrams. The low beams do work. I’ll work my way through the inside fuses.


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[TBaganATX]

I have a never ending trace on power drain. Discovered that the headrest TVs had constant power and fixed that.. now need to keep searching.. seems like I have to start daily (not my DD) or its dead.. 94 Blazer..


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[PolyMatt]

Replaced the headlamp switch. That fixed it! Good call, thank you. I did notice the dome lamp wasn’t working with broken switch, so might had been a draw on that part of the circuit


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[PolyMatt]

East302

Looks like the head lamp switch was broken, but I’m still getting a .34 amp draw from the 50A lighting circuit. Any recommendations on which circuit I should try next?


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[PolyMatt]

Update: seems to be downstream of the 20A CTSY Fuse 3. When that fuse is removed, is about .0017 Amps.


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