Hello,
I have a 96 Windstar GL 3.8L. Unfortunately the vehicle had some flood damage and I have a few electrical problems I haven`t been able to fix. Fortunately, I`m a technical electronics type, so I just need some pointers.. Here are the issues:

- My airbag control module went out, I put in a replacement and then got the "blown fuse" error code. The original controller had blown the protection fuse when it flooded. I replaced the fuse and now the controller gives me a "21" code. This code says there is a grounding problem, but the new controller is screwed into the floorboard. Any idea how to drill down on this one specifically?

- There is also some kind of false door ajar signal to the GEM module, but only during the middle of a hot day. Normally, if a door is ajar, the red dash lamp will light and if the motor is running, a chiming alarm sounds. If one accelerates to above say, 15 mph, with the door still ajar, the chiming stops but the ajar light stays on. When all doors are closed the light goes out. In my situation, during a hot day, the ajar light will come on and the chiming starts, even if all doors are closed. When the temperature drops, operation returns to normal. I have replaced the GEM module with no luck.

- Keyless entry and cruisue control also stopped working.

I have ordered a complete shop manual and also an OBD-2 scan tool that can also read the Ford ISO trouble codes from GEM and Airbag modules. ($145 ! check it out www.obd2.com) Any help on these specific issues much appreciated.

Tom

 

I don't know much about air bag systems.

I am wondering if there is a way to isolate the door ajar problem. I would try to figure out where the switch in each door is that activates the system. I wonder if it's the same switch that activates the dome light? If that's the case, and the dome lights are not coming on, then it must be a problem very near the gem module with the wiring.

If it has seperate switches for the door ajar, or one switch with a seperate section, I would try to figure out which wire it is, and if it takes a normally closed or normally open signal. I would then jump across or seperate the wire to de-activate a particular door. If you still have the problem I would choose a new door each day to see if you could isolate which door/switch/wiring was causing the problem.

 

Dave,
thanks for sending. From what I can tell, the GEM computer receives all of the door switch inputs and drives the outputs like the dome light, door ajar light, etc. So the door switches don't control the dome light directly. One hypotheses is that one of the door switches is acting erratic with temperature. When the temperature is high, the switch opens even if the door is closed. I guess I could test that using the tecnique you mention: finding the wire to each switch and bypassing it manually. That is a good idea. I wonder if anyone has seen this problem...Tom

 

I would planning on pulling and cleaning all of the switches. If it was a flood car then rust could have built up in one or all of the contacts. Keep some electrical parts cleaner handy. You may also have the same corrosion problem in the door chime module also.

 

Tom if you remove a battery terminal to clear the Light Flash Code does it come back again?

Is it possible that you turned the ignition on before the air bag diagnostic monitor was properly bolted down? That could cause the LFC 21.

This is what the manual says about a LFC 21.........

Normal Operation

The air bag diagnostic monitor measures the resistance between the ground connection at its bracket and the reference ground at Pin C1-18, Circuit 397 (BK/W). If the air bag diagnostic monitor measures a difference of more than 3.0 ohms between the ground at Pin C1-18, Circuit 397 (BK/W) and the ground at its bracket, the air bag diagnostic monitor will store in memory DTC B1921 and flash lamp fault code 21 on the air bag indicator. Should the difference in resistance between Pins C1-18, Circuit 397 (BK/W) and air bag diagnostic monitor bracket ground be serviced or otherwise reduced to less than 3.0 ohms, the air bag diagnostic monitor will store a DTC B1921 in memory.

Possible Causes


A high resistance reading at the air bag diagnostic monitor bracket ground can be caused by:

a poor attachment of the air bag diagnostic monitor due to loose mounting, dirt, or corrosion at the air bag diagnostic monitor bracket mounting surface(s).
a poor reference ground at Pins C2-10 and C1-18 of the air bag diagnostic monitor Circuit 397 (BK/W).


As for the door ajar problem, it's quite common. Usually spraying tons of WD40 (only) into each of the door latches will free up, clean and lube the door ajar switches and they will work right again.