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Discussion Starter #1
Hey guys. I have a weird problem I've been fighting for a while and I just can't track it down.
I have a 1969 Tempest Custom.
SO my turning lights do not operate as they are designed to. If I click the turning signal switch to indicate left both of the front turn lights flash(there are two sets of turn lights in the front), and the two left rear lights flash.
If I click it to indicate a turn right the other set of front turn lights flash and not the others. The two lights on the rear left signal as well as the light over the licence plate, the heater light, and the left Pontiac light on the rear fender.

What I've replaced thinking it might be the problem.
New Turn signal switch
New Turn signal flasher
New ground strap for the rear lights

If I unhook the connector that runs to the rear lights all of turn lights go out including the fronts.

I have some professional electrical experience but I really have no other ideas.
 

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If you are absolutely sure ALL grounds are clean, it would sound like a HOT wire to the right side is crossed to the running lights at some point.
The are multiple grounds, check them all.
Pain in the posi for sure.
 

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There is a bolt on the engine block. The battery neg runs directly to that
Try bonding your body sections to a grounded frame, connect a braided cable to the engine block on the same connection as the neg battery cable and attach the other end of the braided cable to the frame. Then under the car at the rear cross-member attach another braided cable to the body connection for the fuel sensor ground. Then attach the other side of the braided cable to the cross-member. Up front attach the back of the block to the firewall and the passenger's inner fender to the frame.

Kinda like NEC 250, see if that makes a difference.

I use 2 of these kits on the 66 and 67 and I have no electrical problems,

 

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Harness is upside down, or two of the wires in the rear harness are spliced incorrectly.

I agree with rlslavik on this one. A ground wire only allows each light to illuminate, the hot wire determines which lamp to illuminate. Is it possible that the flat harness that goes underneath the drivers seat and towards the rear of the car was plugged in upside down (on either end)? Seems amazing that the left signals would be the middle wires in the harness and work correctly whether the harness was attached properly or not, but it could happen. The other possibility is that the individual wires extending from the harness into the trunk are actually installed (spliced) incorrectly. Easy to figure that out: put a VOM on each wire on the harness connector where it lies near the trunk. Observe voltage present in just one of those wires when the right signal is activated. Similarly find the wire that belongs to the left signal, and all the rest simply illuminate the taillights and license plate.
 
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