I'll try to keep this issue as simple as possible for everyone. My door lock relays were making a buzzing sound when trying to lock and unlock the doors. The locks were showing no hint of working at all. After repeatedly pushing lock and unlock a few times the buzz sounds quickly became weaker until they disappeared completely and the lock would still not work. After replacing with new relays, the same story played out until the relays were quiet again.

Since then, I've replaced my under dash fuse block which solved a couple of other problems. These same door lock relays (which are not located in the fuse block) showed a very brief hint of weak buzzing when trying to activate the door locks and they fell silent once again. Still no hint of door locks working.

Does anyone know the cause of the relays buzzing weakly until they fall silent? What should I test and how should I troubleshoot this problem? I don't want to spend more money on replacing relays if the problem is not getting fixed.

I should also mention that my power mirrors both door courtesy lamps, and dome lamps are not working either. But, there's no relay buzzing with these. My glove box lamps, under hood lamp, and overhead switched map lamps do work (I mention this since the last three are tied into the same circuit as the door courtesy lamps and dome lamps).

Thanks,
Drake

 

Well until you mentioned the other items that don't work I was thinking about the resistor that is part of the door lock mechinism going bad. It is a common failure and can be repaired if you are into disassembling the actuator and bypassing the resistor and putting it back together. With the other things not working I would guess maybe the GEM module. But purely a guess on my part, no expert here by any means

 

I thought of the resistor too, but I figured there's no way all 4 resistors not working at the same time is pretty unlikely (4 doors).

 

Problem FIXED!!! To update you all on this after a very long time (weeks) working on this problem, I discovered why my door lock were not working. It started out the lock relays were buzzing when I pushed the lock/unlock button. Soon after, they went silent.

I figured out that I wasn't getting voltage to the relays and with the power source originating at the engine bay fuse box, I began to do continuity tests between connections along that path. I discovered in one of the two the main wiring harness to secondary interior wiring harness connectors that the hot a at all times wire was not placed into the connector. I placed it into the connector according to the wiring harness schematic and still nothing.

I then looked at the other end of the connector to discover the ground and hot were switched. So, after swapping places between the two wires inside the connector.....Viola! Power door locks work.

Now, the rear passenger lock needs the thermistor mod done to get it operational.

I'm guessing the relay buzzing was probably from the hot wire that was hanging loose was touching a ground source very close to the power door lock relays. Anyway, it works so I'm happy!

This proves once and for all that you CAN successfully convert a manual lock, window, mirror, 2 wheel ABS truck into a full power feature truck including overhead console, power locks, windows, mirrors, 4 wheel ABS truck by transplanting the entire wiring harness GEM module, and both fuse boxes from a donor truck that has all the desired options you're looking to end up with. No, there is no need to re-program the GEM module when doing it this way. Also, the power mirrors, dash gauges, interior lamps, and courtesy lamps are all working now after repairing broken circuits I was able to identify through a lot of work as well.

I'm happy it's over.

Drake

 

Good job Drake. This whole process has taught you much.
You probably know more about converting an XL to an XLT
than anyone on this forum.

Rep to you for your perseverance.

I'm also happy it's over.