Power Door Locks 101

The following write-up is an introduction to the Vanagon & Eurovan power door lock system. It covers how the system works, common failures and a few troubleshooting tips. School is in session!

The power door locks on Eurovans and Vanagons are exactly the same and, in fact, use the same actuators. The system is purely electric. There is no vacuum used at all. The system does not have any kind of "central control." It is a very simple, dumb system. The two front door lock actuators are "masters" and the ones in the sliding door and rear hatch are "slaves." The masters have four wires going to them, one each of the following: red (12 volts all the time), white (12 volts when unlocked), yellow (12 volts when locked), and brown (ground all the time). The slaves do not have the red wire. Inside the actuators there is a motor section and a switch section.

LOCKING:
When either one of the front doors is locked (button pushed down or key turned in door handle), the switch section in the actuator moves down and provides incoming power from the red wire to the yellow wire. The yellow wire circuit within the actuator also provides power to the motor via a “logic wheel,” also inside the actuator. The motor inside spins until the logic wheel cuts off power to the motor, and the actuator is now in the locked position. Power flows to all the other actuators through the yellow wire, to the logic wheels inside of each, thus running the motors in each until all are in the locked position.

UNLOCKING:
When either one of the front doors is unlocked (button pulled up or key turned in door handle), the switch section in the actuator moves up and provides incoming power from the red wire to the white wire. The white wire circuit within the actuator also provides power to the motor via the logic wheel. The motor inside spins until the logic wheel cuts off power to the motor, and the actuator is now in the unlocked position. Power flows to all the other actuators through the white wire, to the logic wheels inside of each, thus running the motors in each until all are in the unlocked position.

Common failures:

The  most common failure is a corroded master actuator or broken wiring in the driver's side door jamb.

Master actuators are mounted vertically with a rubber bellow located at the top. The bellow dries out and falls apart over time. Plus, they are in the front doors under the roll-up window slots where water can get to them; so they are prone to corrosion failure. Slave actuators, by contrast, are located in the sliding door or rear hatch; no window slots where water can get in. Plus, they are mounted sideways. Corrosion failure is typically not an issue with these. Broken wires in the door jamb are the other common failure.

When the Vanagon was introduced in 1979, there were NO wires going to either door. There was one speaker on the dash, and that was it for tunes. Then they added door speakers: two wires. Then they added heated power mirrors: six wires. Then they added power windows: six more wires. Then they added power door locks: four more wires. The whole thing was an afterthought; the design is poor. Broken wires in the driver's side door jamb are a common problem. Just about every Vanagon will have some broken wires in this area.

Eurovans, by contrast, were designed from the get-go with power everything, door speakers, the works. So, the design of the door jamb wiring is WAY better, and is not nearly as prone to failure. What is (not so) funny is that even though VW fixed the design, on some vehicles they blew it on the assembly. A reader of our site sent in a photo of the wiring on his 2001 Eurovan (Thanks, Bob!). The photo clearly shows how an overzealous assembly line person installed a wire tie in a poor locaton under the dash, causing the wires to kink sharply every time the door was opened and shut, which in turn caused premature failure. Sometimes you just can't win!

Failure mode: The most common failure mode on both Vanagons and Eurovans is that one of the master actuators is no good, and simply will not run the system when locked or unlocked. Another less common failure mode on Vanagons is where one of the front doors is locked, and the system goes into a ghostly lock-unlock-lock-unlock mode, over and over. In that case, there is usually a broken wire in the driver’s door jam harness AND a bad actuator in the passenger door. What is happening is this: when the passenger door is locked, the internal switch tells the internal motor in the passenger side actuator to go to lock position, which it does, and power is sent out of the yellow wire. However, power can’t get to the driver’s side actuator via the yellow wire because of a broken yellow wire, so the driver's door actuator, still in the unlocked position, continues to send power to the white wire. So, the passenger actuator tries to unlock but can’t because it’s corroded, so it stays locked and continues to send power out of the yellow wire. So, now both the yellow AND white wires have power, and the system goes poltergeist. You have to fix the broken wire(s) and replace the bad actuator(s).

Troubleshooting: First check for continuity in the wires running to the driver’s door actuator. If you are sure the wires are good, just get a new actuator and replace the one in the driver’s door. If that does not fix it, take the one you just removed from the driver’s door and put it in the passenger door. If that does not do it, you have two bad actuators and both have to be replaced.

There is a quirk in the system on Eurovans that is not the case with Vanagons. Whereas neither front door on a Vanagon will lock when open (the button just won’t go down), the passenger door on a Eurovan will. That means you can very easily lock your keys in the vehicle, often in the ignition, often with the engine running. That was simply an oversight on the part of the VW engineers. The good news is that the passenger door master actuator can be turned into a slave actuator by simply cutting the red wire going to the passenger door. Now the only lock that will operate the system is the driver’s door, which cannot be locked when the door is open. This means that, in order to lock the system, you either have to have the key in your hand, or you must be inside the car with the door closed. At the very least, I would strongly recommend a hide-a-key for you Eurovan owners!

The nice thing about this system is its simplicity, and the ease with which one can add keyless entry. All 2001 and newer VW Eurovans have factory keyless entry built right into the key. This was optional on some earlier year-model Eurovans. GoWesty sells a keyless entry system that can operate the factory power door lock system. It is very inexpensive, comes with instructions specifically for wiring into the factory system, and requires actual connection to only four wires in the vehicle. It comes with two remote entry key fobs, and can literally be installed in 20 minutes. It can also be programmed to lock and unlock the doors automatically with the operation of the ignition switch if you wish!

If you do get locked out, a hammer works pretty good to get back in…Cheers!

For a visual reference, refer to Robert Bentley manual page 97.163 & 97.164 for the circuit diagram of this system.

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