When The Pop-Ups Don’t Pop-Up

We got a question today about pop-ups that don’t reliably pop up.  With some experience with this type of failure, we thought that this would be a good time to address it.  The failure is described this way: “When I turn on the headlights, the lights come on but they don’t pop up – they just light up the engine compartment.  It doesn’t happen all the time, just once in a while.”

These cars are old, and old cars have electrical issues.  The most common causes of this failure are all found around the motor that raises and lowers the lights.  First though is a quick description of the headlight mechanism.  Unlike the 914 and other concealed headlight cars, the 944 has only one motor to actuate the pop-ups.  Located on the right side of the engine compartment, the motor has a relay and a four-prong plug in it, sometimes protected by a rubber cover.  Unfortunately this cover has long since gone away on many cars, leading to the conditions that cause the failure.

1. Jiggle the four-prong plug going from the harness into the motor next to the relay.  If the lights work properly, then the problem is in the connector.  The easiest way to fix this is to slightly – very slightly – bend the prongs in different directions to “tighten” the connector.  Work the connector in and out to work any corrosion off both sides.
2. If there is no response to the connector, jiggle the relay.  If the lights respond, then you should replace the relay. The part number Is 928 615 116 01.  Make sure that the contacts are all clean – sometimes the problem is the actual connector in the motor housing that has suffered some corrosion.
3. If the relay does not respond, the problem is in the motor itself.  The rotation of the motor is controlled by an electrical contact mechanism inside the motor housing.  If it is dirty or worn, it can cause this situation to occur.  The mechanism can be disassembled and cleaned/serviced, but not something that you want to attempt.  The part number for the motor is 477941379B, and used ones are almost $300 and a new one is almost $1000.  (We have used headlight motors in stock at $220.)

Rarely is the problem in the switch.  When a switch goes bad, it is normally because the switch itself has failed, and in that case nothing works as it is supposed to.  Might there be a switch issue?  Maybe, but probably not.

If I had to guess I would say that the problem is in the connector, #1 above – that is most common cause of this failure.  The connector is in the engine compartment, open to the outside air, and also subject to vibration, for a long time.  Relays also go bad for the same reasons. While we have had some issues with the contacts in the motor going bad, it is rare.