[DeTomaso] Headlights turn on but buckets don't open

MikeLDrew at aol.com MikeLDrew at aol.com
Tue Feb 16 23:31:12 EST 2010


In a message dated 2/16/10 20 18 56, peter-kovacs at sbcglobal.net writes:


> What is the sequence to chase down the problem? 73
> 

Realize that the headlight switch controls two totally separate systems; 
one is an illumination system (turns lights on and off) and the other is an 
erection system (there you go Larry, go ahead and knock that one out of the 
park) which raises and lowers the headlight buckets.   Their relationship is 
only coincidental (in fact on the very early, pre-US cars, those two 
functions were controlled separately by two identical headlight switches, with one 
of them located to the left of the steering wheel on the dash, next to the 
windshield wiper rotary switch).

Your illumination function is working fine.   You therefore need to 
concentrate on either the wiring going to/from the motor, or the motor itself (or 
more accurately, the gear).

The headlight system uses the same POS plastic gear as the windows.   If 
you haven't already substituted a brass gear in there, then there's a decent 
possibility that the gear is broken.   The next possibility is 
electrical--the limit switches can fail.   It's possible, for example, that the 
'headlights up' limit switch, which shuts off power to the headlight motor when the 
lights come all the way up, has failed, and thinks that the lights are up 
already, and is therefore suspending electrical power to the motor.

If I was going to troubleshoot the system, since I'm an electrical idiot, 
what I would do is to manually crank the headlights halfway up.   The lights 
turn on and off with the ignition key turned off, but the motor will ONLY 
run when the key is turned on.   So, I would turn the manual knob (you have to 
push in, that is, push towards the outside of the car, to get the gears to 
engage and then you turn the knob to raise the lights, VERY slowly) until 
the lights were halfway up.   Since the lights are presumably down and won't 
go up, to experiment, I would then get in the car, and with the key turned 
off still, I'd turn the headlight switch on.   THEN turn the key.   The system 
should be powered now and the lights should go up.

What happens?   Any sound of the motor turning?   Or a deafening silence?

Assuming the buckets didn't move, I would then turn the headlight switch 
OFF.   Do the headlights lower normally?   If so, then you've verified that 
the motor is getting power, the gear isn't broken, and the headlight buckets 
operate properly in one direction at least.

Do all that stuff and report back to us.   Based on your findings, people 
with more electrical smarts than me (which is to say, just about everyone) 
can then discuss methods to pinpoint the exact source of your problem, 
assuming it's electrical.

If your problem is purely mechanical, then all you have to do is pull the 
headlight motor and gearbox out of the car, and change the gear.   This is a 
non-trivial exercise with the radiator in the stock location; if you have a 
lay-down radiator, it's a piece of cake.   If your radiator is in the 
standard position, you might gain some relief by removing the upper radiator mount 
bolts, and tilting the radiator forward slightly (which will probably 
require moving the radiator fans first).

I have successfully removed the headlight motor and gearbox without moving 
the radiator, but it was a pretty significant challenge.   The motor/gearbox 
are bolted to a stamped steel plate, which is secured to the inside of the 
fender with three M5 (10mm head) bolts.   With those bolts removed, the 
plate/motor/gearbox are then withdrawn down and back, into the driver's side 
wheelwell (so you'll have to remove the left front wheel).

Let us know what you find out!

Mike



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