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 and upgrade a DeLorean lock module. Two, actually. One was a total hack job (every single wire was cut, the D4 diode was burnt, and most of the other diodes were cut. The other module looked like new.
The problems with these lock modules, even when they were new, are:
- The module is connected through a big (25A) circuit breaker.
- 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! The solenoids heat up and the internal wiring gets fried (along with, possibly, the car's wiring harness).
- The module also causes a big paracitic drain.
The fix is simple thanks to the work of others! There are a few solutions out there with varying degrees of modifications required. One solution was developed by longtime DeLorean owner Elvis Nocita in Germany and has been field-tested for years. You can find the latest (at the time of this writing) version of his writeup here. His upgrade requires very few modifications and it can all fit in the original housing. Aside from a different routing strategy for the wiring modifications, the following example follows his procedure.
And it's completely plug-and-play with the DeLorean. Note that I used a male terminal on the 12v supply wire since I'm scrapping the old circuit breaker (now replaced with an inline fuse).
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. A 3mm pin terminal remover (the yellow ringed thing) is optional, but will make your life a lot easier if you're removing a bunch of pins from the stock housing.
Basic tools needed.
Parts
The minimal components are all available from DigiKey at a total cost of around $30 shipped (as of early 2025). I recommend getting extra terminals, as they are very inexpensive and you may waste 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); I ordered a few sealed versions too, but they blocked a transistor pin just enough for me to choose the open frame.
Minimal parts needed for the modification. | ||||
| Description | Qty. | DigiKey PN | Location | Notes |
|---|---|---|---|---|
| Inline ATO fuse holder | 1 | FHAC0002ZXJA-ND | 12v hot wire | |
| Female connector housing, red | 1 | A112388-ND | 12v wire | Use this if you're connecting to the circuit breaker. |
| 6.35mm (0.25") quick connector, female | 1 | A99669CT-ND | 12v wire | Use this if you're connecting to the circuit breaker. |
| Male connector housing, black | 1 | 480053-4-ND | 12v wire | Use this if you're bypassing the circuit breaker and connecting directly to the wiring harness. |
| 6.35mm (0.25") quick connector, male | 1 | A27925CT-ND | 12v wire | Use this if you're bypassing the circuit breaker and connecting directly to the wiring harness. |
| Relay, SPST, Open frame | 2 | A51AO12VDC1.6 | RLY1, RLY11 | Rated for 40A at 14v. |
| 10k ohm resistor | 2 | A105970CT-ND | R2, R12 | |
| Transistor, NPN Darlington | 2 | 497-5776-ND | Q1, Q11 | |
Additional parts for remote harness.You can choose whatever you want here, but this is what I used (and considered). | ||||
| Description | Qty. | DigiKey PN / Source | 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! | |
| Rists-style 4-pos 3mm housing and terminal set | 1 | British Wiring | Alternate to all of the above if you want to match the DeLorean connectors. Consider buying extra terminals just in case... | |
Additional parts, if needed.In case there is more wrong with your lock module... | ||||
| Description | Qty. | DigiKey PN / Source | Location | Notes |
| Capacitor, 1000 uF 16v, axial | 2 | 56-MAL212535102E3CT-ND | C1, C11 | I actually did not use this one, but it will fit better than the ones that I used. |
| 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 | |
| 3mm sockets | 8 | British Wiring | For the 9-pin connector, module side | |
| Rists-style 9-pin connector | 1 | British Wiring | The 9-pin connector; plugs directly into the DeLorean wiring harness. | |
Remote Module
There are a ton of options for this one. My criteria was primarily the aesthetics of the remote and wanting one with only two buttons. I settled on this really inexpensive module on AliExpress which works well so far.