Headlight Motor Circuit – Operation and Repair

Overview

This guide covers the headlight motor circuit for the Porsche 944 with its 16v engine (1989-1991). It explains how the motor raises and lowers the headlights when you flip the dash switch and provides steps to fix issues like headlights not moving or being misaligned. A working headlight system is crucial for visibility and safety, especially at night, and this guide is tailored specifically for your 944.

Tools Required

• 10mm (3/8 inch) wrench
• Screwdriver (flathead and Phillips)
• Ohmmeter
• Wire strippers and crimping tool (for connector repairs)
• Sandpaper (fine grit)
• Small file (for relay points)
• Lithium-based grease
• Automotive GOOP adhesive

Parts Required

• Fuse, 7.5A for control wires – 944 615 111 00
• Fuse, 25A for motor supply – 944 615 112 00
• Replacement relay (if needed) – 944 615 115 01
• Replacement motor (if needed) – 944 624 013 03
• Rotary switch brushes (if damaged, source locally or fabricate)
• Four-pin connector (if damaged, source compatible replacement)

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Headlight Assembly Removal

Step-by-Step Procedure

Step 1: Check the Fuses

1. Locate the main fuse panel under the dashboard on the driver’s side of your Porsche 944 (16v).
2. Check the 7.5A fuse in slot 16 (red/green wire) and slot 37 (yellow/blue wire). Replace with 944 615 111 00 if blown.
3. Check the 25A fuse in slot 2 (red/blue wire). Replace with 944 615 112 00 if blown.
4. Turn the ignition on and test the headlight switch. If the headlights still don’t move, proceed to the next step.

Step 2: Test the Headlight Motor Circuit

5. Disconnect the four-pin connector from the headlight motor, located near the motor assembly in the front of your 944.
6. Turn the ignition on but keep the headlight switch off. Use an ohmmeter to check voltages: brown and yellow/blue wires should read 0 volts; red/green and red/blue should read 12 volts.
7. Turn the headlight switch on. Check again: brown and red/green should now be 0 volts; yellow/blue and red/blue should be 12 volts.
8. If voltages don’t match, test the relay (944 615 115 01) and dash switch with an ohmmeter for continuity. Replace if faulty.

Step 3: Remove and Bench-Test the Motor Assembly

9. Follow this link to ensure this step – Headlight Assembly Removal – of the process is followed accurately for your 944.
10. Disconnect the motor shaft from the linkage using a 10mm (3/8 inch) wrench.
11. Remove the four-pin connector and the three screws holding the motor to the car with a screwdriver.
12. Take off the rubber covers and inspect the relay points. File them if burned, or replace the relay (944 615 115 01).
13. Test the relay coil with an ohmmeter (should read about 65 ohms). Replace if there’s no continuity.
14. Check the four-pin connector for damage. Replace with a compatible part if needed.
15. Remove the rotary switch cover and inspect the brushes. De-solder and replace any damaged ones with brass or appliance repair parts.
16. Test the motor by connecting it to a battery: ground the case to negative, connect a wire from the green motor wire to positive. If it doesn’t turn, replace the motor (944 624 013 03).

Step 4: Adjust Headlight Position

17. Start the car and turn on the headlights.
18. Unscrew the linkage from the motor shaft with a 10mm (3/8 inch) wrench, holding it steady to avoid turning it.
19. Manually reposition the headlights to the desired height, then reconnect the linkage to the motor shaft.
20. Test the headlights by turning them on and off. Repeat if the position isn’t correct.

Step 5: Lubricate and Maintain the Linkage

21. Apply lithium-based grease to the ball joints in the headlight linkage to reduce resistance.
22. Turn the manual control knob on the motor (with fuses removed) to cycle the system. Note any rubbing and adjust the linkage alignment if needed.

Step 6: Repair Rubber Boots (If Damaged)

24. Clean and lightly sand the split areas on the rubber boots.
25. Tape the inside of the split to hold it together, then apply layers of automotive GOOP to the outside, letting each layer dry.
26. Remove the tape and apply GOOP to the inside. Trim excess once dry.

Post Procedure Checklist

• Turn the headlights on and off several times to ensure smooth operation on your 944.
• Check that the headlights sit at the correct height when raised and fully retract when off.
• Inspect the motor and linkage for unusual noises or binding.
• Verify all fuses are intact and correctly rated after testing.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manuals
• Youtube