Fixed! central locking.

[benfidar]

Hi all, I am still suffering from my central locking woes. I took it to a mechanic who basically sat on it for a month without really trying to solve the problem. I am now looking for another mechanic. Any recommendations for Chicagoland?

[Vincenze]

Maybe, this repair tutorial will help.

https://www.e30zone.net/e30wiki/index.php/Central_Locking_problems

[thegoynextdoor]

Take out your module first and hook up power to it to verify it works on the bench: looking at the schematic, apply 14.4V power/GND to the appropriate pins. Then test all functionality by bridging the input pins that correspond to lock/unlock (driver, passenger and trunk) to GND with a set of tweezers. You should hear the relays engage, pause, and then disengage. Also test the inertia switch by giving the box a nice hard flick to trigger it. Try not to spam any inputs because the thermal fuse is designed to pop open for safety purposes if one of the relays or lock switches were to get stuck or if there was a short. Check for continuity across this thermal fuse first if nothing is working.
Once you've determined that the module indeed works, you need to check that it's getting voltage at the red power wire. If not, it's usually because there's corrosion on the door harness connector's contacts. You'll need to clean them with a baking soda/water solution. Probably best to let the connector with the male pins soak in a cup. For the female pins, I'd soak q-tips in said solution, jam them into the female contacts, and let them sit to let the solution work its magic. By the way, this connector is usually hard to remove the first time you do it because the aforementioned corrosion will be sticking it in place. You just gotta pull it by the harness wiggle it it until it slides off. Don't worry, you won't damage the wires. Don't think about using a flatblade to pop it off because you won't do anything but break old plastics (ask me how I know).

[benfidar]

Update! I soldiered the melting resistor. I made a grave error that you have to be careful not to repeat: DO NOT use standard soldier. Try to melt the soldier on the resister and stick it back together. If you do not, as I failed to do, you can over load and seize all of your actuators. This was an expensive mistake!

[benfidar]

Central locking is done. $500 in parts, $480 in labor. Wow. All 6 actuators were seized. Now they are all new and the driver's door lock is rebuilt. Fully functional. What a wild ride. With an old car I knew and accepted that there would be something. The project is still ongoing. Should be done by the end of August.