Odd power failure on 99 Expy

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Jul 24, 2003 | 03:44 PM

hokiebob

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Odd power failure on 99 Expy

An odd thing happened today-went outside and the Expy was dead-totally, no clicking at the starter and nothing electrical inside worked. I checked the battery voltage and it was 4 VDC! I put a charger on it and it started charging but the A/C blower would cycle on/off with no key in it. I decided to jump it and it started ok after a little while but drove very funny......wipers didn't work sometimes, radio goes on/off for no reason, 4X4 works sometimes, windows won't go up/down--very odd.

I have two questions:
1: Is this the "relearning" that the electrical system goes through?
2: Doesn't it seem odd that the batter was that dead over night.

The generator seems good, as I have 14 volts when running. The truck is a 99 and still has the motorcraft battery, but in my experience with other cars, this seems like an odd failure. I haven't done a component drain test yet.

any thoughts would be much appreciated!

thanks
bob

Jul 24, 2003 | 04:19 PM

Rtpjunior

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From: Bronx, New York

Odd power failure on 99 Expy

Check your GEM module, it sounds like the culpreat......

Jul 24, 2003 | 04:23 PM

PaulC

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Odd power failure on 99 Expy

Could very well be the GEM, but a dying battery plays Hell with this model. It may not be the culprit, but I would consider replacing it anyway as a preventative maintenance item.

Jul 24, 2003 | 04:26 PM

GR8Diesel

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From: Burnsville, MN

Odd power failure on 99 Expy

I'd suggest the battery be your first inspection point. If you have a dead cell or two then it is possible the GEM / PCM will not have the proper voltage to operate which could erroneously turn on other devices and run the battery into the ground.

Jul 24, 2003 | 04:47 PM

hokiebob

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Odd power failure on 99 Expy

Thanks guys for the quick help. Any clue what a GEM goes for, and is there anything special to replacing it-the book talks about downloading its configurations to the NGS tester before changing, then reloading it on the new one???? Is there any way to check the GEM?

The battery is charging tonight-if still dead tomorrow morning, I'll replace it first.

Jul 24, 2003 | 04:50 PM

GR8Diesel

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From: Burnsville, MN

Odd power failure on 99 Expy

If memory serves me correctly there are a lot of nasty issues with the GEM and the PATS system that keeps you from swapping from a junkyard.

Check the battery and let's hope that is it. If not we have the same vehicle and I have the service manuals and will help you through the process to best of my ability.

Jul 25, 2003 | 02:33 PM

hokiebob

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Odd power failure on 99 Expy

Thanks for the help. I charged the battery and let it sit over night. This morning it started and everything acted normal. I'm not sure what happened but it seems ok now-maybe the big lightening storm the other night messed it up!