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Old 07-02-2010, 11:49 AM   #1 (permalink)
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Default Tail Lights are out

After a recent wheeling trip my tail lights stopped working and I received a fix-it ticket on the way home. This is a 1973 Scout II 345, 727, d20. The problem is that the headlights, turn signals, brake lights, and hazards all work so I believe the ground is fine. Just the running tail lights are out. I know the PO did some shoddy wiring fixes that I will address in the future, but I am trying to track down where the short is that is causing this issue.
I am trying to track the wire that is going to the tail lights but I am not sure from the headlight switch which wire to trace. (I don't have the time to trace all of them right now).
Here are a couple pictures of what I am dealing with.


In the second picture I know that the headlights are being run off the center green wire (with the white wire attached to it), but which of these wires goes from the switch to the tail
lights?
The red wire off to the left in the second picture is missing a fuse because it keeps popping when I put one in, but the Scout ran fine without it previously and the tail lights worked.
Thanks for any help!
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'73 Scout II 345/727/d20
D44, D70HD with 37s
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Old 07-02-2010, 12:21 PM   #2 (permalink)
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Default Re: Tail Lights are out

Just our of curiosity, have you checked to see if your brake switch at the peddle is still working/ in the same location?
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1978 SuperScout II, 345, T-19 close, Dana 300, Dana 44 front and rear with 3.73 and Detroit in the rear, custom bumpers and on-board air.
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Old 07-02-2010, 12:55 PM   #3 (permalink)
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Default Re: Tail Lights are out

Quote:
Originally Posted by 78SSII View Post
Just our of curiosity, have you checked to see if your brake switch at the peddle is still working/ in the same location?
The brake lights work fine, so I assume the switch is working properly.
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Old 07-02-2010, 01:44 PM   #4 (permalink)
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Default Re: Tail Lights are out

I think the headlight switches for Scout IIs and T/As are the same -- at least m/y 1973.

So, I assume they are wired the same -- at least in the beginning.

My 73 T/A manual shows the parking lights running from the "post" (unused in your wiring) "above" the red wire that "blows a fuse" all the time... in your second picture

At this point, I do not know, but you may have a bigger mess than you think you do.

And, I may be wrong comparing a T/A headlight switch (from wiring diagram in my manual) to your PO's "custom wiring"...

But, this is a "diagram" of the T/A switch - "+" = wire connected; "-" = no wire - from the manual's wiring diagram

+
+ + -
+ +
- +

This is your headlight switch in your second picture

-
+ - +
+ -
+ +

These are from the "point of view" of holding the switch with the "knob" pointing up -- looking at the wire "posts"

Last edited by RobertC; 07-02-2010 at 02:07 PM..
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Old 07-13-2010, 06:34 AM   #5 (permalink)
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Default Re: Tail Lights are out

How did you resolve the problem? I have a 71 800b and my left brake light won't work. Right side was working, but after I took it apart to look at the wiring, now it won't work either.

Where should I begin?

Thanks for any advice.
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Old 07-13-2010, 07:53 AM   #6 (permalink)
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Default Re: Tail Lights are out

It's still not resolved. I have a short somewhere that keeps blowing a fuse, but I haven't had the time to chase it down yet. Good luck!
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Old 07-15-2010, 01:35 PM   #7 (permalink)
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Default Re: Tail Lights are out

Finally had some time to track down the culprit. It was the aftermarket license plate light. The wire had been pinched where the spring assembly raises/lowers the plate. It had worn through the wire insulation and was grounding the positive lead which was spliced into the taillight wire. Causing the taillights to not work and keep blowing the fuse.
What a pain. I really need to get around to just rewiring the whole truck.
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Old 07-16-2010, 08:42 AM   #8 (permalink)
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Default Re: Tail Lights are out

I think my issue it two-fold. I think I knocked off a ground wire on the right side somewhere and I also think my turn signal switch needs to be replaced, which I hear is a common culprit of one brakelight not working.

I am going to take tomorrow morning and pull it all apart and see. If doesn't work, I may just buy a rear wiring harness and redo the back end of 71 800b.
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Old 07-19-2010, 02:50 PM   #9 (permalink)
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Default Re: Tail Lights are out

Quote:
Originally Posted by gkaider View Post
I think my issue it two-fold. I think I knocked off a ground wire on the right side somewhere and I also think my turn signal switch needs to be replaced, which I hear is a common culprit of one brakelight not working.

I am going to take tomorrow morning and pull it all apart and see. If doesn't work, I may just buy a rear wiring harness and redo the back end of 71 800b.
No need to replace the turn signal switch unless some component is broken or burnt beyond repair.

Ya disassemble and CLEAN the switch contactors, they are nothing more than a form of contact points and will be dirty and scummed over with heavy oxidation and old rotten grease. And that is a prime area to find spider nests INSIDE the horn/signal switch area which adds to the overall grubbiness.
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