Current Draw - 1998 Chevy Tahoe

[bugnutz]

Issue:
Battery runs dead during an 7-8 hour time of sitting (occasionally).

Truck Desc:
1998 Chevy Tahoe / 4DR / 4x4 / 5.7 V8 / AT / 110k miles

Question:
Has anyone had problems similar to this in any Chevy Tahoe or GMC Yukon of a similar year?

What has been tried and known:
I have placed a test light in line with the negative terminal of the battery. The battery has been tested good (will take a charge) and there are no problems with the alternator. The test pulses strong with all fuses plugged in. When the radio fuse (#19 - 15A; inside) is pulled, the pulsing seems to slow down slightly. When the radio fuse is returned and the AT CASE fuse (#2 - 20A; inside) is pulled, the pulsing is slightly less than before. Both the Radio and the AT CASE fuse have to be pulled for the test light to turn off.

I have consulted the wiring diagrams and the radio fuse only goes to the radio and the AT CASE fuse only goes to the Transfer Case Control Module (at least thats what the diagrams showed). I have replaced the Transfer Case Control Module in the past, but it should not burn out after 3 months. I thought the two fuses may share a ground. I ran an extra ground from the radio wire to the chassis (did not work).

The only thing I can think of is that after driving in the rain, the transfer case gets wet and shorts the control module under the dash. The problem there is the first time this happened there was no rain, and I looked under the truck for any damp or poor connectors.

Other things to Mention:
There is an aftermarket radio, that was professionally installed with proper factory harness adapter (the first time it happened, the factory radio was installed). I have an after-market trailer brake controller installed (unplugged when not used). This truck is a bone-stock, daily driver that does some occasional hauling. It isn't taken off-road or abused in any manner.

If anybody has any input that would be great. I just don't know what else to do.

[hermsbigdaddy]

i have bout the same problem u do, only difference is it takes mine bout a day of sitting before its dead... i have a 97 c/k 1500 worktruck, and i have went thru 3 batteries, had the alternator tested, tried replacing all the fuses...nothing seems to fix it, either. thout maybe it could be door switchs, hood light, or dome light, but unhooked all of these 1 at a time and still does it....hopefully theres something simple im not checking...any help would b great!!!

[bugnutz]

My Drivers side door switch is intermittent and last night I tried removing that and making sure it had the lights in the off position. That had no effect on the current draw.

Mine is obviously a 1/2 ton (because it's a Tahoe).

[mrjohnwayne]

i'd pull the radio out and check the wiring making sure there is no damaged insulation on the wires. Lots of sharp edges behind there.

[bugnutz]

I checked all the wires when I pulled the radio out. I even ran an extra ground from the radio to the chassis to see if that would solve the problem. Unfortunately, that was not the case.

[gmcguru32]

my uncle had the same problem and he took it to his mechanic and they told him that it was his keyless entry key-pad.
he took everything out for the keyless entry and everything is good now.
might not be the same as yours but its worht a try

[bugnutz]

I think I may have it for now?

I have always cleaned the connection between the battery and the cable where it touches battery directly. The GM geniuses have a double layered terminal where the outer cable runs to a junction box and then to the alternator and the under-hood fuse box.

I tore that cable apart from the battery and it was very corroded between the 2 cables along with the stud. I believe the corrosion was not allowing the alternator to properly charge (which explains the intermittency of the problem). The radio and AT transfer case control fuses only account for 15mA of the total 50mA of draw in the off and idle position. That would take a couple weeks to drain the battery, and not 7 hours.

Word of advice. Keep it simple.