No RR Turn Signal w/Headlights On

[Foster48x]

Anybody know why the RR turn signal on my 80 FI would stop working with the headlights on? It's only the right rear signal. all of the tail lights and turn signals work great with the headlights off except the reverse lights (which are also not working right now but I dont think its related to this problem, but I may be wrong).

The fuses, headlight and tail light grounds are good. I've also tried to diagnose the issue with the wiring diagrams, but with the spaghetti mess under the dash its been somewhat problematic trying to figure out what to put the volt meter on. What route do you guys think I should take to troubleshoot the problem?

Rick

[So Cal Mark]

bad ground on the circuit board in the rr taillight assy. very common

[Foster48x]

I guess I'll bust out the ole soldering gun again. My tail light circuit board already looks like something out of a sci-fi movie from fixing all the other connections .

Thanks for the help Mark.
Rick

[spider2081]

The rivets used to secure the light contacts to the printed circuit board do not take solder very well. A good quality electrical flux helps even though most electrical solders have flux in them. I found media blasting the area to be soldered helps. Otherwise cleaning with wire brush in a drill or Dremel will help. For a lasting repair the solder has to take to the rivets as well as the board and the light assemblies

[Foster48x]

This is wearing me out . Still cant seem to get the RR tail light to blink with the headlights on even after cleaning all of the connections and soldering the ground to the board (the connection looked good but I soldered it anyway). Actually the RR circuit board has been replaced, it's not the same brand as the left board. Dont know if this makes a difference? Will it create a problem if I directly ground the socket on the RR blinker to the interior of the trunk?

Rick

[So Cal Mark]

no, add as many grounds as you like

[mbouse]

consider adding an additional ground strap between the engine block and the body as well... always helps, never hurts.

[Foster48x]

Just anywhere on the engine block to the frame? Do you use the same guage wire as the neg battery terminal?

[mbouse]

i use approximately 16" of replacement battery cable, black, and attach to the air pump bracket to the inner fender on the passenger side. sure, just about anywhere on the crankcase is adequate. clean contact points are essential.

[Foster48x]

I'll try it. Thanks Mike.

Rick

[spider2081]

I believe all the connections for the right rear light assembly pass through the left rear light assembly. Maybe the problem is the interconnect harness or the left PC assembly.
Grounding the right light assembly by adding a wire to the body on the harness side of its connector would isolate the problem. If the additional ground makes it work the problem is before the right light assembly. Leaving the additional ground can't hurt but if the actual problem is in the left PC board it shouldn't be too hard to fix.

[Foster48x]

Spider2081, The connections to the RR tail light do pass through the left. I've checked just about everything over to the right rear circuit board. Your right, I should probably just go back through everything again with the volt meter just to be sure. I still haven't had time to directly ground the problematic socket. Hopefully it will solve the problem.

Thanks,
Rick

[Foster48x]

Grounding the socket to the trunk just blew the fuse? What did I do wrong?

[So Cal Mark]

grounded the power side

[Foster48x]

Oops! Yup I grounded the hot Good thing I'm not an electrician by trade... or with the Fiat maybe that's not a good thing that I'm not an electrician... oh well, lesson learned.

I grounded the right connection and the right blinker works like a champ.

Thanks for the help once again.
Rick