This is what the finished product looks like. It's modular, so the keyless entry system can be easily replaced in the future.
DeLorean Lock Module Rebuild
Introduction
Here we will rebuild a DeLorean lock module. Two, actually. One was a total hack job and the other looked like new.
The problems with these lock modules, even when they were new, are:
- The module is connected directly to the battery (no fuse)!
- A 1000uF capacitor powers each relay coil. As each capacitor discharges, voltage is reduced and the relay contacts open slowly. Eventually this causes the relay contacts to fuse together, which permanently closes the circuit.
- At this point a lot of current is flowing through the solenoids with no fuse! The solenoids heat up and the internal wiring gets fried (along with, possibly, the car's wiring harness).
The overall process of a fix has been around for a long time and first published by longtime DeLorean owner Elvis Nocita. You can find the latest (at the time of this writing) version of his writeup here. Aside from a different routing strategy for the wiring modifications, the following example follows this prodedure.
And it's completely plug-and-play with the DeLorean.
Tools
You'll need some basic tools and a soldering iron. Some of the stuff below is overkill, but at minimum, you need a wire cutter, a soldering iron and solder, and a wire stripper. I also highly recommend using a solder sucker AND some desoldering wick. There is a LOT of solder on the bottom side and you'll spend forever if you're just using wick.
If you want to make a fancy connector for the remote housing, you'll need a proper terminal crimper. The Hozan P-707 is a versatile choice and a very high quality crimper. The 3mm pin terminal remover (the yellow-labeled thing) is optional, but will make your life a lot easier if you're removing a bunch of pins from the stock Rists housing.
Basic tools needed.
Parts
These parts are all available from DigiKey at a total cost of around $35 shipped (as of early 2025). I recommend getting extra terminals, as they are very inexpensive and you may waste a couple. I've crimped a lot of terminals and I wasted a couple. For that matter, many of these parts are really really inexpensive... you may want to order extras for your next electronics project (or just in case you goof)! Also noteworthy: the relay I chose was the only open frame relay that I could find that was a current production part (from DigiKey and Mouser, at least).
The 4 position housing can be substituted with another housing; I just chose this one because it was compact (but it's quite compact!). You could go for a Rists-style 4 position housing and make it look really "proper!" Just get the correct terminals for your selection.
Minimal parts needed for the modification. | ||||
| Description | Qty. | DigiKey PN | Location | Notes |
|---|---|---|---|---|
| Inline ATO fuse holder | 1 | FHAC0002ZXJA-ND | ||
| Relay, SPST, Open frame | 2 | A51AO12VDC1.6 | RLY1, RLY11 | This is the only open frame relay that I found on DigiKey (I found zero on Mouser) and a few sealed relays that I tried obstructed the transistors. |
| 10k ohm resistor | 2 | A105970CT-ND | R2, R12 | |
| Transistor, NPN Darlington | 2 | 497-5776-ND | Q1, Q11 | |
Additional parts for remote harness. | ||||
| Description | Qty. | DigiKey PN | Location | Notes |
| 4 pos. housing, receptacle | 1 | A107334-ND | ||
| 4 pos. housing, plug | 1 | A112420-ND | ||
| Terminal, pin | 4 | A110999CT-ND | Get extra! | |
| Terminal, socket | 4 | A100459CT-ND | Get extra! | |
Additional parts, if needed. | ||||
| Description | Qty. | DigiKey PN | Location | Notes |
| Capacitor, 1000 uF 16v, axial | 2 | 56-MAL212535102E3CT-ND | C1, C11 | |
| Resistor, 100 ohm, through hole | 2 | A105969CT-ND | R1, R11 | |
| Diode, 1N4002 | 1 | 4878-1N4002CT-ND | D5 | Suitable replacement for obsolete 1N8119 |
| Diode, 1N4006 | 2 | 4878-1N4006CT-ND | D2, D12 | |
Remote Module
There are a ton of options for this one. My criteria was primarily the aesthetics of the remote and how many useless buttons it had on it. I settled on a really inexpensive module on AliExpress to just test out. So far, so good.