Greetings,
I'm hoping someone can shed some light on what's going on with my '99 SCab XLT. This problem has occured 5 times in the last week. After a good warm-up of 20 minutes or so, the airbag and ABS lights come on, and the blinkers and heater motor won't..... After shutting the truck off for about 10 minutes they reset and all is fine....except last night, when I had the heater switch turned off while still driving and it all reset.. When it happens, the hazard lights will still flash, even though the blinkers won't. The fuses are fine (since everything works after a while again anyway). Is there a resettable circuit breaker in addition to the fuses? What do the ABS and airbag lights have in common to the blinker and heater motor controls? This is an intermitant problem, and doesn't happen every time. I'm wondering if the heater motor is the culprit, although I'd think it would blow the fuse. Is there a ground that might be common to these circuits? And I'm still stumped on those darned ABS and airbag lights.... Any and all help will be much appreciated. I'd hate to be stuck in a snowstorm with my family and have the heater go out...
Thanks, and Merry Christmas to all.
Kevin Thompson
Falmouth, Ma.

 

They do share a ground, and they do all route through the IP. Perhaps someone with more specific knowledge of your year can post to help?
Chris

 

At the moment I would agree that a ground is the likley problem.
Remember the blower motor draws a lot of current and will heat a connection that has any amount of resistance and creating heat at that point.
This could cause a temporary open from exspansion and upset all other circuits that depend on the same ground.
A way to tell this is to make an extra ground to the blower black lead and bypass the original ground.
If this stops the problem either leave it or find the bad original ground.

 

I'd pull the connector off the ignition switch at the bottom of the steering column. If it appears burned or distorted, I would replace the switch and connector.

 

Hi Everyone, Mine Was Doing The Same Thing, Took It To Ford This Morning. They Call Me About Three Hours Later, Leak Comming From Driver Side Windshield Dripping On Control Module Fryed It. It Controls Wipers,windows,4x4,radio,heater. Cost 1000.00 Merry Xmas. That Doesnt Include Resealing The Windshield

 

I cannot agree with dominator's assessment since NONE of the affected systems utilize the GEM/CTM. Doesn't mean you don't have a leaky windshield, but I don't see any evidence that your GEM/CTM is affected.

The HVAC and turn signal systems use G200 located under the right side kick panel. The ABS and air bag systems use G201 located under the left side kick panel. Not particularly in common.

If you 4WABS, there is a single switch power feed through the ignition switch that, if lost, could explain all four of your stated symptoms. If you have RABS, the circuit is slightly different.

The circuit gets pretty involved. If you have the EVTM, it can be followed. Look for the circuit that feeds into the ignition switch via terminal B4 and outputs via terminal A4 while in RUN.

Personally, I'd focus on the ignition switch and its surroundings as suggested by momalle1.

Steve