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daniel · Joined: 18 Jun 2009 Posts: 686 Location: Sydney, Australia

I am in the process of rebuilding my car and I have a problem with the headlight system. The lights work, and it will rise up, but not retract. Everything worked before pulling the car apart. Heres what I have observed:

With the headlights on, The white wire only has power (this is the wire with a loop) With the heaglights off, there is no power at the plug at all.
My first thought is, the motor cant lower the lights without power, So I applied power to both the red and white wires, seperatly and together. Nothing.

I am not sure if there is a wiring problem or a contact problem inside the motor. Does anyone know the switching sequence to raise and lower the lights?

PS All fuses intact, relay on motor clicks when lights are turned on and off.

Cheers

Daniel
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Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet

Ozzie · Posted: Sat Jan 08, 2011 9:43 am Post subject:

The cams in the motor or the relay could be causing problems.
Headlight switches fail too.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

leadfoot · Posted: Sat Jan 08, 2011 10:18 am Post subject:

the alloy right angle ears that the lights pivot on are prone to cracking and the lights can cock on there pivot.
Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

Joes924Racer · Posted: Sat Jan 08, 2011 12:05 pm Post subject:

They crack huh... maybe if ya toss,em around... id check the switch
though maybe its a ground or a spring could be binding on one side.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

Used to have the same problem on my 80 NA. The temporary fix was to open the hood and tap the relay on the headlight motor. This would normally caused the headlight to retract. The long term fix was to clean the relay contacts on the headlight motor.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

staticsan · Joined: 19 Jan 2009 Posts: 450 Location: Sydney, Australia

The mechanism is basically a mechanical finite-state machine (says the programmer in me!) and if I remember right, has some not immediately intuitive rules. I found that they will stay up but the lights go out if you turn the ignition switch off but not the lights. It is this sort of subtlety that makes the wiring more complex, though.

It is not hard to pull apart the switching mechanism on the end of the motor. But it's easier to check the relay and the plug; I had a pin nearly fall out the back of the plug which was why mine were unreliable. But the sensor wheel inside can be too greasy, too, which interferes with the contacts eventually.

Wade.

Joes924Racer · Posted: Mon Jan 10, 2011 10:19 am Post subject:

Yopu know the knob that you spin for hand cranking... do that to see if there binding, then move on to the cleaning the relay contacts.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.