23rd February 13:48
1988 ford expedition
Something strange *is* going on there, and my first thought is if
you have problems with both the interior lights and the power windows
you need to check continuity of the drivers' door hinge wiring bundle.
Multiple broken wires, and the dome light switch in the door latch
(and not a jamb pin switch) would cause oddities like that.
If you open the drivers door and the lights or windows start
working, close the door and they stop (or vice versa) and that's it.
The circuit for the dome lights (the step lights are tapped off the
dome lights) should have absolutely nothing to do with the circuit for
the power window motors. The windows are on a 30A automatic circuit
Other than that, get a hold of the factory wiring diagram, it often
provides valuable clues as to common components and power leads - and
don't forget common ground leads. Open grounds are another source of strange stuff.
--<< Bruce >>--
23rd February 13:49
1988 ford expedition
There is an occasional problem with water leakage at the base of the
windshield. It is a small leak and often not apparent to the vehicle
operator. The water leaks onto the GEM (General Electronics Module). The GEM
controls a lot of functions, including the interior lights. It does not turn
on the check engine light. You need to have someone read the PCM codes using
the appropriate scanner. Since only your lights are acting up, I don't think
water contamination of the GEM is your problem. It is much more likely that
the interior and exterior lights are on becasue of a sticky door switch.
Here is my recommendation of how to proceed:
1) Clean all the door latches to try and verify that there is not a problem
with one of the switches. To do this get a spray can of electrical contact
cleaner or WD-40. Using the small tube that comes with the product, spray
the interior of the latch from the edge of the door. Really soak things and
try to spray the cleaner through the mechanism. There is a switch in the
latch. "Gunk" contaminates the switch mechanism preventing it from operating
properly when the door is latched. You are trying to wash the gunk out.The
switches are seperately replaceable, however, usually the problem is just
2) Have some one read the PCM codes and have that problem corrected.
3) Check the GEM to verify that a leak is not contaminating the module.
"*FORD SPECIAL MESSAGE #15773 VARIOUS ELECTRICAL CONDITIONS RESULTING FROM
WATER INTRUSION INTO THE GEM/CJB
SOME 1997-2002 EXPEDITION AND 1998-2002 NAVIGATOR VEHICLES MAY EXHIBIT
VARIOUS UNUSUAL ELECTRICAL CONDITIONS, INCLUDING BUT NOT LIMITED TO: FRONT
OR REAR BLOWER OR EATC STAYING ON WITH KEY OUT OF THE IGNITION, RADIO
STAYING ON AFTER DOORS OPENED AND KEY OUT OF IGNITION, WIPER CIRCUIT FAILURE
CODES, AND MULTIPLE SYSTEM WARNING LIGHTS WITH 'SHORT TO POWER' OR 'LOW
BATTERY VOLTAGE' DTCS. THESE SYMPTOMS MOST OFTEN OCCUR AFTER A RAIN OR SNOW.
THIS MAY BE DUE TO GEM/CJB WATER INTRUSION RESULTING FROM A WINDSHIELD WATER
LEAK. TO SERVICE, REMOVE THE GEM AND CJB FROM THE VEHICLE, SEPARATE THEM AND
INSPECT FOR WATER CONTAMINATION OR CORROSION. IF FOUND IN EITHER COMPONENT,
REPLACE BOTH COMPONENTS AND COMPLETELY RESEAL THE WINDSHIELD.
EFFECTIVE DATE: 04/05/2002"
Again, I don't think the GEM is your problem - I think your problem with the
lights is the door latch switches.