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[924RACR]

Added some notes to repairing the headlight motor for stripped gears. The following is the complete text from the Tech Section with updates; I'll be adding the updates later this week with pics, but am posting it here now for your benefit...

Headlight Raising Mechanism
The headlight raising motor and mechanism are very reliable on these cars, due to a simple linkage design, and the use of only one sturdy motor. The same layout is used on the 924 and 944, but the 931 had the headlight motor on the left-hand side of the car, instead of the right, to allow room for the air flow meter. Otherwise, the systems are identical. Notes in this section about working on the headlight linkage motor can mostly be applied to the windshield wiper motor; though the internal components are different and not interchangeable, the design is very similar.

The relay for the operation of the motor is plugged into the side of the motor housing itself, right next to the connector; these both can be found by pulling back the rubber boot on the side of the motor opposite the linkage. They can go bad, as any other relay, but are easy and cheap to replace.

Be sure to keep all rubber boots and seals intact on the motor and connectors - they contribute greatly to the reliability and longevity of the system.

One possible cause for failure or trouble is the body of the car interfering with the headlight motion; switch the headlights on and off, watching the travel and looking for any sticking. In particular, if the headlight motor will not operate, the linkage can be disconnected from the motor and moved manually. This sticking can be caused by body damage or by misalignment of the headlight buckets. The alignment of the headlight buckets can be changed by loosening the three bolts in each pivot mounting plate on each side of the headlight. The inboard bolts are easy to see just over the radiator; the outboard bolts are reached from the inside of the fender. Body damage may require some manipulation of the sheetmetal to fix.

The electrical connection can be another source of malfunction. Sometimes the pins in the 4-pin connector themselves can get worn, and not provide a good connection. This can be verified if, when the lights are turned off or on, and the motor will not lower or raise, wiggling the connector will cause the motor to move to the correct position. In this case, the pins can be either made to fit more snugly with a pair of pliers, or replaced outright; the connector type used here is a standard AMP connector type, and the pins and sockets can be removed from the connector block with a special tool for this purpose, which can be purchased at any Radio Shack or other electronics supply house. They will also sell replacement pins or sockets to be crimped on.

Usually the failure is in the female side, on the motor. In order to get at the motor side of the connector, the lower rubber boot must first be pried off of the motor; remove the motor from the car by unbolting the linkage and unbolting the motor, then use screwdrivers or similar to pry the cover off. Prying the rubber boot off can be made easier by unscrewing the two flat-head screws that hold the connector/relay to the motor; the rubber boot will pry off more easily once this is done.

Once the cover is off, the whole connector can be seen. The pins are easy to replace at this point. However, often the female pins need simply to be tightened up. There is a small tab in the end where the male connector is inserted which can be gently crimped in for a better contact. Simply tightening these up can sometimes fix a reluctant motor.

Furthermore, the diodes for the control of the motor can be seen. These can fail, especially if the headlights have jammed at some point, overloading the motor. Sometimes the failure can be obvious, as the diode will have blown apart, or will disintegrate at the touch, but the best way to check the diodes is with a diode check function on a multimeter. These can be replaced by anyone handy with a sodering iron, and cost mere pennies at Radio Shack. Looking at the Radio Shack and other electronics catalogs, all available diodes will handle the low voltage (14VDC) and current (about 10 amps) of the motor, so selecting a replacement diode simply becomes a matter of finding the smallest one that will fit in the place of the old one.

The motor, as stated, is very reliable and is unlikely to fail; if the headlights pop up and down numerous times before staying in the appropriate position first suspect a bad or sticky relay, or faulty diodes, before the motor itself. If the relay and diodes check out good, then remove the circular cover plate from the motor gearbox. On the inside of the cover plate will be seen the switching paths for the motor raising and lowering; clean these well and re-grease the gears with good fresh grease, then reassemble and see if that fixes the problem.

Later cars, the 931 and 944 in particular, seem to have been put together without the grease. These can fail in a very frustrating way, wearing the gear on the drive shaft right out with a hollow spot where the gears can slip past eachother if presented with any resistance. In this case, the only option may be to replace the gear itself. Since this is not available by itself, a new or used replacement motor may need to be replaced. However, there is one more option to try first.

On the face of the gear opposite the driveshaft can be seen the contacts that control the motor. These are pressed on to and through the gear with metal tabs. The metal and plastic discs can be removed by prying between them and the phenolic gear face with a knife. Note the indexing of the discs relative to the flat spot on the gear, and rotate them relative to eachother, then reassemble (press back together 120 degrees off the original position). This could relocate the area of highest torque need to a different, less worn area of the gear, allowing it to work again. The motor can then be reassembled in reverse, and tested.

Finally, the headlight motor gets its power and switching signals from the headlight switch. If there are still problems, make sure that the headlight switch is functioning properly and that the correct currents are being passed to the motor connector. Refer to the Haynes manual for the appropriate wiring diagram for your year and model of car.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype