Headlight Problem

[EIPtuningR32]

the other day i manually cranked my headlights down. when i was driving around, for the hell of it, i twisted the light knob on the dash and they came up. "WOW!" i said. then i twisted it back and what do you know.... they stayed up. any ideas on what would be causing this? lights go up but not down? i find this strange because to my knowledge isn't the motor a one way motor? doesn't it go both up and down with the same direction of movement from the motor? Thanks -Charles

[EIPtuningR32]

anyone??

[MPDano]

This would be a question for Alan. I'm gonna guess Relay. Is there a relay that is the same as the relay for the headlight motors? You could then switch them out and see what happens.

[EIPtuningR32]

Originally Posted by MPDano

This would be a question for Alan. I'm gonna guess Relay. Is there a relay that is the same as the relay for the headlight motors? You could then switch them out and see what happens.

true, but if it was a relay then the headlights wouldn't go up or down, not just up. am i correct?

[Danglerb]

Originally Posted by EIPtuningR32

true, but if it was a relay then the headlights wouldn't go up or down, not just up. am i correct?

Early cars use a complicated pair of relays combined with a switch in the motor to control the relay. I don't think it "knows" up from down, so maybe you have it unsynced or something. Maybe with the key off and out and lights off, manually lower then lights. Maybe even with the battery disconnected.

[EIPtuningR32]

Originally Posted by Danglerb

Early cars use a complicated pair of relays combined with a switch in the motor to control the relay. I don't think it "knows" up from down, so maybe you have it unsynced or something. Maybe with the key off and out and lights off, manually lower then lights. Maybe even with the battery disconnected.

i have already tried this (not knowing the extent of what would happen and why) and when i switched the lights on, they came up. when i turned them off, again, they didnt go down

[Alan in AZ]

The relay knows if the pod is up or down based on a rotary switch in the headlight motor...

This switch also has 2 diodes to combine a feeder signal from each of the drive signals (go-up /go-down) and runs this through the switch legs (one for pod is not-yet-up and one for pod is not-yet-down).

So the motor is enabled in go-up mode via the relay while the switch indicates pod not-yet-up, it will also drive in go-down mode while the switch indicated pod not-yet down.

The motor is one failure mode - obviously yours works.

The relay is another failure mode - on pre S4 cars its unidirectional - so since it works in up mode its also OK.

The other failure modes are wiring (switch to relay), the switch terminals or a diode.

Most likely are the switch wiper or the diode.

The diode is replaceable (radio shack) and the wiper can be cleaned adjusted manually.

Alan

[EIPtuningR32]

Originally Posted by Alan in AZ

The relay knows if the pod is up or down based on a rotary switch in the headlight motor...

This switch also has 2 diodes to combine a feeder signal from each of the drive signals (go-up /go-down) and runs this through the switch legs (one for pod is not-yet-up and one for pod is not-yet-down).

So the motor is enabled in go-up mode via the relay while the switch indicates pod not-yet-up, it will also drive in go-down mode while the switch indicated pod not-yet down.

The motor is one failure mode - obviously yours works.

The relay is another failure mode - on pre S4 cars its unidirectional - so since it works in up mode its also OK.

The other failure modes are wiring (switch to relay), the switch terminals or a diode.

Most likely are the switch wiper or the diode.

The diode is replaceable (radio shack) and the wiper can be cleaned adjusted manually.

Alan

GREAT ADVISE!!!!! thanks!

[MPDano]

Yup, Alan is the ruler on our Electrics.

[EIPtuningR32]

Originally Posted by MPDano

Yup, Alan is the ruler on our Electrics.

yeah... i noticed that. he is better than the shop manual!