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'70 Charger hidden headlight motor limit switch #1503841
09/18/13 12:45 PM
09/18/13 12:45 PM
Joined: Nov 2004
Posts: 9,312
SoCal
68HemiB Offline OP
master
68HemiB  Offline OP
master

Joined: Nov 2004
Posts: 9,312
SoCal
I was asked to consult on a buddy's 1970 Charger equipped with hidden headlights. Customer complaint was a large unexplained draw with ignition on. I traced this to a 6-7 amp draw from the motor that moves the headlight doors. Although the gross function of the system is apparently okay (headlight doors go up and down when they should), the motor 'down' circuit is still pulling a load even after the doors are all the way down. Clearly, the internal limit switch is not doing its job.

My buddy's "service manual" is woefully inadequate when it comes to the internal workings of the system. (Although a genuine Mopar book, I don't think it's the full FSM.) It does cover how to diagnose and repair a non-working system, provides warnings about running the motor without a load and turning the knob without disconnecting the harness - but not much else.

This motor was supposedly rebuilt during the tenure of a previous owner, but that sentence now tells you about as much as I know about that rebuild.

Are there any user serviceable or adjustable characteristics of this system short of a motor teardown? I welcome any comments in general, or specific answers to the following two possibilities:

a. There is a small slotted screw at the top of the "differential housing" on top of the motor. Is that of any help here?

b. There is an adjustment at each side so the doors can be allowed to close "further". Even so, if using said adjustment would allow the motor to travel to the limit switch, it would leave the doors horribly out of alignment with the surrounding grille. When I look at the system, the shade-tree side of me wants to "clock" the motor differently on its mount. If I trashed the paint and detailing in this area, would there be much movement to be had?

If the down limit switch is trash, of course the motor needs to come apart. If the switch isn't trash, there has to something to tweak here.

Sorry for the long read. Thank you in advance for any suggestions.


Down to just a blue car now.
Re: '70 Charger hidden headlight motor limit switch [Re: 68HemiB] #1503842
09/18/13 01:28 PM
09/18/13 01:28 PM
Joined: Dec 2007
Posts: 18,153
Mass
DAYCLONA Offline
I Live Here
DAYCLONA  Offline
I Live Here

Joined: Dec 2007
Posts: 18,153
Mass
All the motor limits are internal to the motor, mechanical and electrical, the screw your talking about on top on the motor is for worm gear end play, common problem on 70 Charger motors that leads to cooked motors, time for a motor teardown, assuming the correct motor is being used?

Re: '70 Charger hidden headlight motor limit switch [Re: DAYCLONA] #1503843
09/18/13 01:55 PM
09/18/13 01:55 PM
Joined: Nov 2004
Posts: 9,312
SoCal
68HemiB Offline OP
master
68HemiB  Offline OP
master

Joined: Nov 2004
Posts: 9,312
SoCal
Thanks for the reply.

As for the incorrect motor question, I was not aware that there was anything that would bolt up and still not be the right motor. Someone more knowledgeable than I about '70 Chargers has already seen the car (prior to the electrical diagnosis) and did not find anything amiss. He will also likely be a source of other motors to try.

Could you clarify what the "common problem" is? Worm gear end play? Is there no steering-box-like tweaking to be done here (tightening the screw) that might help?

[/grasping-at-straws]


Down to just a blue car now.
Re: '70 Charger hidden headlight motor limit switch [Re: 68HemiB] #1503844
09/18/13 04:06 PM
09/18/13 04:06 PM
Joined: Aug 2009
Posts: 1,315
Ohio
J
jlatessa Offline
pro stock
jlatessa  Offline
pro stock
J

Joined: Aug 2009
Posts: 1,315
Ohio
Search "TOPHER" on the 70 Charger Forum, he's the guru, rebuilder, and
general good guy.

He'll help you solve it.

Joe

http://www.headlightmotorman.webs.com/
Email --> headlightmotorman@live.com

Last edited by jlatessa; 09/18/13 04:09 PM.






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