Pimping My Ride – A Remote Control Power Door Lock System

1972 BMW Bavaria

We don’t own a “modern” car, that is to say, one that is less than 10 years old. Our newest car is the Alfa Romeo Alfetta Sprint Veloce, which reached its 27th birthday this year. The BMW is seven years older than the Alfa – a 1972 Bavaria.

Not that I haven’t driven modern cars. We’ve recently driven (rented) a Volvo S40, Land Rover LR3, Ford Escape and a Dodge Charger (with an anemic 2.7L V6) among others. One of the features that Chris misses when she drives the Bavaria are the remote power door locks that cars have these days.

1972 BMW Bavaria Front Door Jamb

I’d seen a US $99.99 J. C. Whitney remote control power four-door lock system that looked sufficiently crappy, so I bought it, but it’s NLA. (Amazon has a pretty crappy looking one)

I knew the installation would be straightforward but labor intensive, so I put it off for 8 months. I started by removing the front door interior panel and plastic water barrier. The instructions are not very specific so I had to figure out where to put the actuators.

The actuator is basically a solenoid that is fed a positive or negative voltage to pull or push a rod. It has to be located parallel but slightly off axis from the lock rod because the installation instructions have the lock rod bent in a loose “Z” shape so there is some “give,” I guess.

1972 BMW Bavaria Front Door Actuator Location (behind panel)

It took me a few tries to bend the actuator rod into the right shape. It’s basically like a bicycle spoke (with less flex) with a nipple at the end where it goes through the hole at the end of the actuator arm.

I actually broke one of the rods so I ended buying two more actuators on eBay, which include the bracket, rod and rod connector. I tried a DT Swiss double-butted spoke (2.0/1.8/2.0) that I use on my bike but it was way too flexible.

The actuator installation on the front doors was actually straightforward because there was room for the actuator and the rod to connect to the existing door lock rod.

An included rod adapter connects the actuator’s rod to the door lock rod. Two setscrews hold the door lock rod and one setscrew holds the actuator rod.

1972 BMW Bavaria Front Door Lock Adapter

I used some thread locker on the setscrews. This view shows what the rod adapter connections look like (though it is actually mounted behind the door panel). The rear door’s lock rod location didn’t really offer a good place to mount the actuator. The manual window crank mechanism was close to the lock rod. There wasn’t enough room for the rod adapter either. Since the door lock button is located toward the front of the car, there is an aluminum u channel “connecting rod” and various mechanisms that translate the up and down motion of the door lock button to the rear of the door where the catch is located.

1972 BMW Bavaria Front Door Lock Adapter Position (actually mounted behind door panel)

I used the bracket that was included in the kit to mount the actuator across a gap in the door. Since I couldn’t use the rod adapter, I drilled a hole in the existing connecting rod for the actuator rod. I also put a rubber grommet in the hole at the end of the actuator to reduce the backlash on the rod when it moved in and out.

The wiring for each actuator is just two wires.

972 BMW Bavaria Rear door lock solenoid

I drilled holes in the door and pillars for the wires. Running the wires from the rear involved removing the front shoulder belt mount from the center door pillar, the center pillar cover, front door sill and assorted sections of carpet. I put shrink tubing over the wires where they would be exposed to the door opening and closing and grommets in the holes. I made the one hole larger than the other so the wire would slide back into the door. Sometimes it kinks. A professional would know how to do this.

1972 BMW Bavaria 1. Hole drilled in connection rod 2. Grommet inside of actuator

I mounted the control box next to the fuse box because there was a perfect space for it. The pair of wires from each door makes a home run to the mounting location of the control box. There are two wiring plugs on the box. They each have about 200 wires coming from them. The actuator harness has two +12v lines, two ground wires and the blue and green wire from the actuators.

1972 BMW Bavaria electric door lock wiring between door and jamb

I removed the fuse box and relays so I could hook up wires from the rear of the fuse box. This also involved tracing all those stupid lines in the Haynes wiring diagrams, which I don’t even know if they are for my car.

I also removed the flexible left air vent tube that goes over the steering column for easier access when pulling the wires from the passenger side. I removed a bunch of wires from the control harness that I wasn’t going to use – like I said, there were 200 wires. I zip tied and stuffed the rest of the wires that I hooked up behind the control box.

1972 BMW Bavaria electric door lock control box wiring

Since this is really like a modern cars’ remote locking system, there are connections to flash the parking lights, a timer for the interior light, the horn, a remote starter and a control for a trunk actuator (which I didn’t install). I only connected the parking light flashers and the interior light. There is also an option to lock the doors when the ignition switch is turned on and to unlock the doors when it’s turned off. I didn’t connect the horn because it’s always annoying when locking the door and the horn blips. But I’m reconsidering after forgetting where I parked the car at the airport a few weeks ago.

There were a couple of problems during installation. First, I had to clean and lubricate all the door locks because the 34 years of grease on the fittings was hard. There was a lot of friction even when pulling and pushing the door locks by hand. After cleaning and lubricating, they worked a lot more easily.

1972 BMW Bavaria door lock control box mounted next to fuse box (the loose black wire is the antenna)

After I had everything wired up, the four-button remote worked OK for a while. Then it started blowing the 8 amp fuses in the actuator’s +12v lines every time I pushed the lock and unlock button. There was a factory reset that worked for a while but then they started blowing again. I thought about using 15 amp fuses and the manufacturer’s installation support guy confirmed that. With four doors, you need 15 or 20 amp fuses. (I had to be very persistent trying to get questions answered – it took four calls to the manufacturer).

It was basically a straightforward installation, but it took me about a week because it took me a long time to figure out where and how to do things. The documentation basically tells you how to wire it. Since it’s a generic kit, there’s no specific hardware installation information. The manufacturer says it should take 4-6 hours to install. All for a more modern car.

I don’t think Xzibit will be saying, “Oh, snap!”