Resolved 1990 Pop up headlight issue

[shdwmsk]

Drivers headlight doesn't retract, goes up fine when manually retracted.

Already tested the following per the Service manual pg 8-244/245 and are working as they should:
Headlight switch
Passing Control relay
Pop-up Motor relay.

Have also replaced the motor with one that worked on the bench. The one I removed also worked on the bench after removal.

Replaced the capacitors in the Passing Control relay today and the drivers head light still does not retract. No corrosion, only slight discoloration on the board holes for C3 and R6. Have pictures, can post them if you need to see.

So I started checking plugs with a multi meter.
I do not get power to pin 5 of the drivers headlight motor harness plug. Also do not have continuity between pin 5 of drivers and passenger plug. I do have continuity between the passenger side pin 5 and pin 2 of the passenger control relay (PCR). Looking at the circuit diagram, I should have continuity between all 3, both pin 5's and pin 2 of the PCR. Correct?

How is this wire routed inside the body harness? The circuit diagram looks like after the PCR, it goes through the body harness plug C-72, then to passenger side headlight motor plug, then branching off to the drivers side. Is this the correct routing?

 

[CrackedDSM]

Simple test is just use two paperclips or two small jumper wires to jump the first two wires on either side of the passing control relay's plug at the same time (effectively bypassing the passing control relay). If the headlights pop up and down as normal then the capacitor replacement didn't work and something in the board is bad.

Also: take it from someone who had this issue, check the actual button that makes the popups pop up and down (circle button next to the gauge cluster, not the headlight switch on the stalk). If that switch is bad or faulty, it screws the entire system up.

 

[19Eclipse90]

Looking at the circuit diagram, I should have continuity between all 3, both pin 5's and pin 2 of the PCR. Correct?

Yes, that should be the case. This is where I would start trying to diagnose this further, especially if everything else tests fine.

FWIW, the pop up motor relays that I’ve seen as “bad” are not always dead-dead. That is to say that when performing the tests described in the FSM, they seem to pass. Only when comparing against the readings of a “good” relay could I tell that there was something not right with the “bad” ones. I’m foggy on the exact details and it sounds like you have a wiring issue anyway, but I thought it might be worth mentioning.

If the car has power door locks and they function properly, the power door lock relay is the same as the pop-up relay so you could repeat the test and compare the results against that one, just as a extra verification, in case. Again, it sounds like your issue is elsewhere.

How is this wire routed inside the body harness? The circuit diagram looks like after the PCR, it goes through the body harness plug C-72, then to passenger side headlight motor plug, then branching off to the drivers side. Is this the correct routing?

C-72 is on the driver side near the interior fuse box. The engine compartment harness starts at / around the interior fuse box, along the driver front fender / frame rail, to the front of the car, underneath the radiator, and up to the passenger headlight and that side of the car. I’m sure it’s all a matter of perspective but I would say the driver side is “first” and the passenger side branches from the driver side as the driver side is nearer the C-72 harness connector junction. As long as it makes sense to you, and it sounds like it does, I’m sure we’ll be able to help figure this out.

 

[shdwmsk]

Awesome information from the both of you.

@CrackedDSM your talking short pins 1and 3, then 2 and 5 correct? Ill see what that does before digging into the connector and harness.

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@19Eclipse90

Yes, that should be the case. This is where I would start trying to diagnose this further, especially if everything else tests fine.

Thanks for the info on the routing. If bypassing the PCR shows same results, I will dig into the harness. Not looking forward to that. Plug looks visually ok, but I can easily check if the pins themselves tonight with a multi meter. Also will compare with the central locking relay.

May also temporarily scab in a wire bypassing the original Pin 5 drivers headlight and see if that fixes it. If it does, then its something in the harness.

 

[shdwmsk]

Got it fixed.

The wiring splice for the down command circuit was bad. (From pin 2 of PCR to pin 5 of headlight motor). No idea how the passenger side was even working either. Any connector that was used as a splice had completely disintegrated.

The location of the splice is in the large harness, hidden behind the washer bottle neck. Picture below has the location circled in yellow, but actual location is hidden by the washer bottle filler neck. Was able to reconnect with a crimp on butt connector and a covered in shrink wrap. I did remove the headlight lift motor of ease of access.

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[danl]

I’ve had great luck using the “shrink and seal” butt connectors meant for marine or power sports applications. Gardner Bender makes some that are stocked at Home Depot. Proper non insulated crumpets required! If you only have space for a non insulated butt connector, I follow it up with adhesive lined heat shrink. Without the adhesive lining they tend to fail quicker and you are making the same repair in a couple years time.

Gardner Bender 22-10 AWG Butt Splice Heat Shrink, Assortment (24-Pack) GBX-TK - The Home Depot

Protect electrical connections from wire pullout, moisture intrusion and abrasion by using this Butt Splice Heat Shrink in Assortment from Gardner Bender.

www.homedepot.com