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Headlight Actuator Problems

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Benjamin Zwissler

Headlight Actuator Problems
« on: March 20, 2016, 03:01:15 PM »
I'm reassembling my car after the paint is finished and have gotten to the

headlights.  I cleaned and lubed the headlight assemblies while they were

out and replaced an assembly that had the center bar for the "up" brace

broken out.  (By the way, Rimmer Brothers has very nice, brand new

mechanical linkages for a great price.) Although everything worked fine

before I disassembled it for paint 18 months ago, I'm now running into a

couple problems.

First, there's is no "up" voltage on the blue (U) wire from the headlight

switch.  If I put voltage on the wire manually the left side headlight

operates perfectly.  Looking at the wiring diagram, the wires runs from the

main light switch to a three way connection to feed the HL lift controls

and the hi/lo beam switch.  The hi/lo beams work fine so the signal from

the HL switch to the HI/LO beam switch is working.  I haven't started

investigating where the signal is getting lost to the lift mechanism. Does

anyone have any likely culprits or know where that three way junction is?

From the front, it looks like the wire disappears into the large bundle

that runs from the right front back to the firewall and enters the dash by

the fusebox.  I'm assuming the junction would be near the headlight switch

or the hi/lo beam switch but it'd save some time is someone's BTDT and

knows where it is.  Again, this worked before I started the paint process

and I haven't done any work in the dash area.

The next problem is that only the left side HL works properly.  The right

side seems to do everything right except the motor is running backwards,

this causes it to bind against the "up" brace when it tries to go down.

I've triple checked the wiring and its right, both external to the motor

and internal.  Remember that I fixed the broken brace and I'm wondering if

the broken brace wasn't a "fix" to a backward running motor.  The car had

been in a front end accident before I got it and the repair was done

sloppily.  I assumed the brace was broken in the accident, but I might be

wrong.  Also the wiring for the "red" connector has been repaired multiple

times but it seems to be correct as best I can tell.  I'm not sure if

reversing the ground (BLG/B) and power (RLG/UO) wires would reverse motor

direction anyway.  Would it?  I know on TR4/4As you can switch from

positive to negative ground and the motors still turn the right direction.

I don't know how the diodes would cause this and I'd rather not reverse the

ground/power wires just to see what happens. Any hints?

Thanks, Ben Zwissler

Columbus, IN


Ben Zwissler

Columbus, IN



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Bill Derksen

Re: Headlight Actuator Problems
« Reply #1 on: March 21, 2016, 02:24:53 AM »
Is there power on the blue wire on the right H/L? If not, my next

suggestion would be to check the connector under the centre grille in

the dash - see if there are two blue wires on one side of that connector

and that they both have power.

On the right light, I suspect that the broken brace is a result of the

motor running backwards. Quite possible that it was like that from

factory. Reversing the RLG and BLG wires on the connector won't affect

the diodes - the motor current does not go through them.




Benjamin Zwissler

Re: Headlight Actuator Problems
« Reply #2 on: March 26, 2016, 12:15:41 PM »
I've got the problem fixed --- for now.

I reversed the wires to the motor and it reversed direction and works as

designed.  In troubleshooting it I once again removed the actuator and

opened up the limit switch and diode box.  All in there was fine.  I'm not

sure why the motor runs backwards when connected per the ROM, but I'm done

worrying about it.

My other issue with no "up" signal on the blue wire were with the original

wire harness and stiff, cracked insulation and open wires within it.  A

previous repair had failed within the heat shrink tube I'd added to the old

wires to keep them from bending and breaking --- that didn't work.  Then

fixing that wire caused another old wire to crack and break...  :-(

I really, really would like to replace the harness (both the main harness

and the front fan/headlight harness) but boy that looks like a lot of work

and $$$s. I see British Wiring has the main harness for $750. Does it

include the harness that runs under the top of the headlight cowl and

contains the fan wiring?  My plan for now is to hope I don't disturb

anything for a while and that doesn't cause any more cracked and broken

wires.  I'm sure that won't work forever.

Thanks Tom and Bill for your helpful suggestions.