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Lost my Headlights


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On my '86 720....I lost my headlights.  I was coming home and they were flickering while on highbeam.  About 1/2 mile from the house, I smelled a burning nylon smell....maybe rubber.  I turned the HBs off, and it seemed to go away.  When I got home, looked at them, on highbeam and I think that I was losing the Driver's Side lowbeam.   Shortly afterwards, they went out.  nut/N  I don't even have a highbeam indicator light.


Today, I checked all of the the fusible links at the battery.  They all are passing 12v (or at least they light up my testlight).  The 2 headlight fuses are good and the testlight shows that they are passing current.


The relay above the fuse box...it seems to be working.  It clicks when I turn on the lights and also when I flip on the highbeams.  I switched out the one from Ole-Blu (my parts 720) and the same thing. 


At the relay plug....it seems like I only have 12v on one plug and, only on lowbeam.


Got any ideas?



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Forget the headlight relay. It only chooses hi or low beams and provides a ground to turn them on.



After 35 years the grease on the headlight contacts has become hard and or dirty and the switch is not making good contact. Resistance will cause heat and that's what you smell. Unscrew the two part 'clam shell' around the steering column to get access to the headlamp switch. It might be best to remove the steering wheel also to really get at and disassemble it enough to spray inside. Get a can of aerosol electrical contact cleaner and lubricant and spray it clean.


If you have a parts truck just swap the headlight switch. Clean and keep the old one for a spare.


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I am gonna take it off tomorrow.  I spayed it from the outside and got one of my high-beams back...still no blue indicator light.


Assuming that I am able to clean it enough to get it back to work...should I lube the contacts?  If so, w/what?

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Well, I probed the heck out of it and it is not the switch.


I fooled w/the switch jumping it w/a probe and nothing different.  I took it apart and cleaned it and filed the contacts....nada.


I took the assembly off my parts truck and plugged it in...same symptoms.  The contacts on my switch were sorta messed up, so I swapped out that part of the assembly.  The assembly between the 2 720s is not the same as one is a tilt-wheel and the column is not the same OD.


Sometimes I get a dim blue glow on the indicator.  When probing the back, I can tell which contact is for that as when I jump it, I can see a spark.  I am working in the dark w/a flashlight and dome light.  


The left headlight has about 11v on low-beam, and less than that, like 10v on high-beam.  The right side seems OK...both headlights, on both high and low-beam.


I have no left high-beam.  It appears to have, about, 7v and doesn't glow at all.


I really doubt that the smell was burning grease.  The plastic housing is/was slightly burned.


Are there any other connections between the switch and the headlights?

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soemtimes if the connector is burnt . it will be high resisitnaceon the contact.  get some sandpaper to ectch the inside of the contact.

Hope for the best

I dont know 720s. but if you get soem voltage then there is a voltage drop somewhere. one can use a meter or test light. closes to the batter and fuse box will have higher voltage and work your way to the headlaight via all the switches and see where it starts to drop off voltage or test light dims


get soem wires and put the battery across the light just to make sure the lamps(elements) are good

Edited by banzai510(hainz)
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It is not the switch contacts.


I've used 2 switches.  I've jumped the contacts w/my probe.  I pre-followed ur directions and cleaned the contacts.  The "New" contacts are in good shape (the old ones weren't).


I have voltage at the lights...it varies, see above.


When I jump the high-beam contact ....I think there are 2, I get no blue dash light, but I get a teeny spark....I doubt that you'd see it in the daylight.....sometimes I get a dim blue glow, and I  doubt that I'd see that in the daylight..

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Has any grounds been added to the lighting system, if so remove them.  Make sure all grounds are clean and have continuity.  Is the a ground frome the back of the head to the firewall?  This is usually a bare braided wire and sometimes is conected to the rear most exhaust bolt/stud.


This is a newer truck but addresses the same ground i am talking about.




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