Headlamps not parking properly

[davekit]

Fun and games with popup headlamps! When I bought the car, the headlamps worked fine, and the vendor said he had replaced the motors - the old ones were in the car. Over time the headlamps got more sluggish and eventually stopped altogether. I manually wound the lights up, and got through the MoT, as they still illumimated ok.

I dismantled the lights to find the cause of the lack of popup. The motors were completely dead, but the old ones seemed to work. This was established by applying an earth to the brown wire, and +12v to the green wire. I wonder if the motors had actually been changed? I changed the motors over, so first problem fixed. Second problem was duff gas struts, so new ones are on order from Poland.

Now the lamps go up and down, but don't stop in the right place. There is a crank on a spline which changes the rotary motion into up and down motion. Easy fix, I thought!! I adjusted the spline, for the lights being up, but the down position was slightly raised. Tried setting to the down position, but now the up position is wrong! Currently when the lights are turned on, the lamps rise a short way; and when the lights are turned off again, the lamps continue their upward movement to the top and then return to the down position. Instead of the two parking positions being 180 degrees apart, it is as though they are 45 and 315 degrees apart. What is controlling this? Can it be adjusted? It has me baffled!

[brinkie]

The popups can be compared with windscreen wiper motors, they have a parking position, but in this case there are two parking positions, up and down. There is a conducting disc inside the motor where three contacts trace its surface.

Note there are cuts 180 degrees apart on two traces and one is continuous. When the lights are switched on (or subsequently off), a double relay, one for each motor, will activate which spins the motors, until the relay disengages itself when the circuit is cut, i.e. when a contact is over a cut in the trace.
This is a fairly simple system, there are no electronics involved. However, you have to fix the spindle which pushes the lamp up and down to the motor correctly, otherwise they will "blink" out of sync.
Problems which may arise: a faulty relay which keeps engaged so the popups keep spinning. dirt on the disc causing a premature cut in the circuit so the popup will stop spinning early, or blown diodes on the motor, which can cause all kinds of mayhem.
For proper troubleshooting I'm advising to connect one motor at a time.

[davekit]

Hi Robert
Thanks for the info, where would we be without you?
I tried the motors individually, and the one behaved perfectly. The other stopped in the wrong place, so it appears it was overriding the 'good' motor when they were running together. It looks like there must be a dirty spot on the disc of the 'bad' motor, or one half of the relay is sticking.

I took the cover off the relay, and it looked almost new inside, and nothing obvious amiss. When it stops raining long enough, I'll swap the motors over which should confirm whether it is motor or relay at fault. Meanwhile, I tried running the motor continuously to see if any dirt would clear, but no joy.

The only other thing might be blown diodes. Where are they? There is a flying lead on the motor to a terminal also on the motor - what is this? As the whole motor assembly is encased in wax (presumably to stop water ingress), I don't want to open it up unnecessarily. I might experiment on one of the dead motors first, to see what's what, maybe even get it working again - who knows?
Cheers - Dave

[davekit]

Definitely the motor which is at fault!

[jamescarruthers]

Didn’t Jeff discover recently that the rear wiper motor is the same as the headlight for motor? Could you bolt it on for troubleshooting purposes? Or did you nicely confirm it by swapping them left to right?

[jifflemon]

errrr I don't remember that!

Then again, I don't remember much these days......

[jamescarruthers]

errrr I don't remember that!

Then again, I don't remember much these days......

Maybe I dream some of the mad stuff you come up with!

[davekit]

I swapped the motors left and right.
I would be very reluctant to touch the rear wiper, having eliminated multiple faults to get that working! From memory it doesn't look like the headlamp motors, and in any case it has only one park position, not two. And parking is now the issue!