2002 Explorer door locking issues

I have a 2002 Explorer XLT 4.6L. Recently have had some problems with the electric door locking system. The horn will chirp twice when arming the locks with the remote keyfob as if a door is not closed ( the doors are actually all locked). All doors are shut because the dash 'door ajar light' is not on. The interior light and passenger exterior mirror lights stay on for 10 minutes then turn off by the battery saver. The driver mirror light does not illuminate at all, but when checking it found out the bulb is ok. The drivers side door lock switch will not lock the doors with the key out of the ignition. The keyless entry will sound the horn when try to unlock the doors with the code. When pressing 7/8 and 9/0 simultaneously to unlock the other doors there isn't any response. I have pulled the latch out of the drivers door to check the door switch and find it is ok.
I hope some can help or has found a solution because this is giving me a headache.:banghead:

So are you saying that the doors will lock with the driver's door lock switch if the key is left in the ignition? Does it need to be in any particular position (run, off, ACC) or just in the key cylinder switch?

I think you have your "all unlock" code mixed up. Pressing 7/8 and 9/0 simultaneously will lock all doors. When you enter your code, the driver's door will unlock. To unlock all doors, you have a few seconds to then press the 3/4 button.

-Rod

Good catch Shorod... You are correct. The doors will not lock when i press 7/8 and 9/0 together. The key has to be in the run position in order for the door lock switch to work on the drivers door armrest. ( the last position the ignition switch is before the starter is engaged).

It really sounds like a door switch making the GEM think a door is ajar.

You mention the door ajar light is not on, but is that even with the key in the run position? If you open a door, does the door ajar indicator come on? Does the unlock button on the passenger door work?

It seems like you need some good wiring diagrams of the door lock and interior lighting system. If you'd send me a Private Message with an e-mail address that can accept PDF attachments, I'll e-mail you the wiring diagrams for those sections.

-Rod

Yes the door ajar light will illuminate on the dash when any door or back liftgate/window is opened, with the key in the run position. The passenger door lock switch will operate without the key in the ignition at all ( the way it should operate at all times.).

A friend down the street has worked at a Ford dealership and still has a friend that works there. He said for me to take it to him and he would run my system thru and check the GEM module which will check each door to make sure things are ok before I tear everthing apart..

I will let you know the outcome when i have this done.

I do have the Haynes repair manual. Are the wiring diagram in this manual lacking information?

I haven't looked at a Haynes manual to determine if it's lacking anything. It's typically a bit safer to say the factory manual or info on Alldatadiy (since it's reprint of the factory manual) should be more complete.

I guess they changed the functions of the GEM somewhere between 1998 and 2002. Most of the power lock functions are part of the Central Security Module (CSM).

Each of the lock switches (driver's door, passenger door, and liftgate switch) share inputs to the CSM. It would be interesting to probe the signals at the CSM and compare what they look like for the driver's door switch to see what it shows for the inputs when the key is removed versus when the key is inserted. Compare that against when the passenger door switch is used. Since they share inputs, the problem can't really be the CSM, but must be something between the battery/ground and the CSM for the driver's door lock switch.

Since the passenger door lock switch works correctly, it seems like possibly a broken wire in the junction between the body of the truck and the door. I've seen broken wires there on a few occassions. Seems odd this would happen on a 2002, unless the driver's door sees a lot of opening and closing. Maybe the locks are getting power /ground through a neighboring circuit when the key is in the run position?

If after scanning the systems nothing obvious stands out, I'd suggest you pull the driver's door lock switch and see if you get the correct supplies to it and the proper outputs, both with the key installed and removed. If everything's correct at the switch, check the junction between the door and the jamb. If that's fine, then you get to trace between there and the CSM. The CSM is located on the pillar behind the right hand rear seats. There will be a fair amount of wire to inspect in that run.

-Rod