Early 86’
Turn headlights on, they illuminate and come partway up.
If you:
1) turn the motor manually a little, they will pop up
2) when they are partway up, turn them off and they go all the way up, then back down

I pulled my other 86’ nose to nose to compare and it looks slightly different. Now, the car with issue is a euro front, so maybe that accts for it looking a little different. Bottom line not sure why the motor always stops at the same spot.

 

its possible its a dirty relay contact,
take relay out and cover off ,
clean all 4 of the contacts,
put a smear of D 100 on the relay contacts .

 

Will do. I'll also test it in my other 86' and swap them as well to see what happens.

 

I just fixed the same problem with my '84. Do what Stan suggested. But also try to lube all the moving parts/linkages behind the front splash cover on the driver's side with spray lithium grease. That worked for me.

 

Making progress.
-Motor when not connected to the arm works perfectly. When connected, it always stops at the same spot (20% on the way up).
-Noticed the driver side light assembly was brushing the body, so I now know how to adjust it's position.
-With it adjusted and all parts lubricated(cleaned) it moves much smoother
-Also noticed the one of the C-clips on the arm attachment to the motor was missing(thankfully no damage, since it hadn't come off). Added new C-clips.
-Once done, light still only goes the same amount up.
-I took the relay out of my other 86' and will test

Curious, if the motor works normally(without the arm connected), why would the relay fail(stop) under load, but only on the initial way up? When I turn the light off, it cycles the rest of the way thru like it should.
Does the one part work thru one relay(since there are several within the main relay), then when you turn it off, another relay takes if from there? Just curious as to how it all works, given the issue.

 

Maybe the motor is kaput and 20% is where the load hits a point it can’t handle, is it still trying at that point if you give it a helping hand?

 

It is still trying at that point. I apply a few turns on the hand crank and at any moment it could finish the full range up, but that point can vary. Again, the weird thing is when I turn the lights off, it'll then go all the way up from the 20% stopping point on it's own.

 

I speculate the issue is actually inside the headlight motor. similar to a windshield wiper motor it has a track with a contact wiper that it uses to sense position of the motor for parking. in the case of the windshield wipers there is only one park position, however in the Headlight motor it is slightly more complicated as it has 2 parked positions 1: Down, and 2 Raised. if you look at the wiring diagram of the "Folding Headlight Motor" you can see these wiper connections.

When the headlights are turned on, the headlight switch supplies power to terminal 56 which then is bridged via the contact wipers to 86 which sends the current back to the headlight relay to close the relay and power the motor. as the motor rotates it will eventually reach the point where the wiper track breaks connection with terminal 56 and the motor is depowered by the relay to park the headlights in the Raised Position. while this occurs the wiper track also bridges the connection between 86 and 30b.

With 30b and 86 bridged, if the headlights switch is turned to the off position, the relay sends power into 30b which returns on 86 to again close the relay contacts to power the motor. the motor will stay powered until the ring has rotated to the position where the contact is broken between 30b and 86. Park Position Down,

What I suspect is happening on your case is that there is possibly a bad spot or contamination on the wiper track causing the connection between 56 and 86 to loose contact. essentially telling the relay the motor has reached the Raised Parked position. as you manually turn the motor eventually you get past the bad spot and the connection between 56 and 86 is reestablished causing the relay to continue driving the motor to the fully raised position. this could easilly be tested by checking for continuity between 56 and 86 at the point where the motor stops. If confirmed you can likely fix it by opening up the motor and cleaning the wiper tracks and reassembling it.

 

Great information, Simon. So, once the headlight motor stops at the 20% up position, unplug the motor and check the resistance between pin 1 & 3 on the motor plug? If there isn't any, that's likely my issue. If there is, then that isn't the problem. Just making sure I'm understanding the diagnostic procedure correctly.

 

Yes, you've got it.

Let us know what you find.

 

With probes on 1 & 3 with lights at the stop position, ohm meter set to 20k, it read -2.54.

pins are in sequential order

Also, removed relay from my other(Hank) 928 86’, still produced same result. Put original in other car(James) and relay worked normally.

 

With HL relay in, key on and HL on, do you show voltage at 1 and or 3?

 

Relay in, turn headlight on…… 11.94 volts
-with pos on #1 and neg on #3



I was able to get alligator clips on.


ohm reading
-with lights down (1.04) *key off
-with lights at 20% up position (.10) *key on
-with lights at 20% up position (-2.36) *key off

 

I recorded the cycle, hope it shows

 

If you are measuring 11+ volts between 1 and 3, then there is NOT good contact there. Try shorting between 1 and 3 during the lift cycle and see if the motor continues past the premature stopping point.