If you can hear the motor spinning then the bushings inside the motors have disintegrated and need to be replaced. Post 587 in my build thread has a picture of what I'm talking about.

https://www.thirdgen.org/forums/ltx-...ml#post6076436

If nothing happens, then you need to study a wiring diagram and test voltage at terminals and trace back to where the problem starts. Post 1277 of my build thread has a wiring diagram for a 1988. I'm not sure how the diagrams vary from year to year.

 

Hi guys,

I know the headlamp door control module is hard to come by nowadays especially if, like me, you live in the UK. The headlamp movement on my car ('88 Formula, 350TPI) has been fine for most of the 18 years since I've owned it, (though I had to replace the motors a few years ago and fitted the upgraded gear parts etc at the same time). But a different fault has recently developed. The headlamps go up OK when switched on, but they don't go down again when switched off. Does anyone know whether a fault in the module can cause the headlamps to not retract (yet still open normally on switch on)? And does anyone have any thoughts on which component is most likely to have gone faulty?

I have taken the module out and re-soldered most of the PCB components, The connector pins were the first to get re-soldered, of course, but I did most of the rest of the solder joints as well for good measure. I stayed away from those wire links on the PCB - I assume they are fuses? - because I was not sure whether heat from soldering would damage them - they appear to be intact and making good contact with the PCB. But the lamps still won't close on switch off.

Thanks for any info!

 

Check your tail light fuse.

Lon

 

Many thanks, Lon.

The tail lights are working normally, but I took the fuse out and checked it anyway with a DVM - and it is OK, So I put the fuse back.

However - now, the headlamps are retracting again. Not every time - but most times. It seems that if I turn the lights off again too rapidly after the doors have opened, there's a chance they may not retract. On the occasions when they don't retract, I can now hear a slight tapping noise, two or three clicks, presumably the relay in the control module not changing over successfully when it gets the signal from the motors that travel limit has been reached?

So I am guessing it's possible I might have a fault developing in the module but it's intermittent right now?

Thanks for your guidance about the fuse - I appreciate it.

 

Do the light bulbs turn off or stay on when the doors are stuck open?

 

The headlights remain on only while the switch is in the 'on' position and the headlamps are raised. They go out, as expected, when the switch is in the 'off' position, whether the headlights actually retract or remain raised.

 

I think there are multiple sets of switches inside that relay control module.

• One set of switches are controlled by the relay and the purpose of those switches is to alternate voltage polarity on the motors to cause the motors to move forward or backwards, thereby moving headlight doors up or down.
  
• The other set of switches are internal to the solid state module and the purpose is to turn the motors off after the doors fully open and close. I'm not 100% certain, but I think it does this with a load sensing circuit. The motor current will go high when the doors run up against the limiters and that will trigger the load sensing circuit to shut off the motor.

Now here is the important part.... If your headlight modules can open and the motors properly stop running, then that means the relay functions and the solid state module functions too. The only difference between doors opening and doors closing is the polarity is reversed to the motor. When the doors open, the motors are powered by the two Fusible Links (red wires, one for each motor). When the doors close, both motors are powered together by the same white wire from the headlight switch in the dash which is passing power from the Tail Fuse. If one motor goes down and the other doesn't, then look for a problem at the headlight module. If both motors do not go down, then look for a problem in the circuit feeding the white wire (all the way back to the Tail Light fuse).

The other possibility is that the doors themselves are not running smoothly and getting hung up on the way down. This would cause the motor to strain and maybe trigger the load sensing switch in the solid state module, turning off the motor before the doors close.

 

Many thanks for your thoughts, QwkTrip!

The electrical info is really useful in helping me to understand how it's supposed to work. I will investigate further based on what you've said.

I was already beginning to wonder whether perhaps the door pivots or the linkages might be mechanically stiff - will investigate that. I have greased them with a spray grease, but perhaps I'm not getting the grease into all the pivoting parts.