Turn Signal Problem

[wubie317]

Recently, my left turn signal decided it would no longer work when the brakes are on. It's works fine when I'm not stepping on the brake.

I have a feeling it's a short or a bad ground or something like that. If y'all were me, where would you look? I'm thinking I'll start in the taillight itself, as it seems like the most reasonable, but could it be elsewhere?

Would love to hear your ideas!

[Pdr1966]

I have been improving right rear not operation when lights are on.
One step to improvement was cleaning grounds on both inner fenders/engine bay as a start
I did also remove both taillight PCB s and cleaned all the chalky corrosion -and ran them through a cycle in the dishwasher (When my wife was away).
I suspect between these two starting ideas you will see an improvement
Note the twilight PCB are remove from the housing easily by releasing snap clips, you do not need to dismount the twilight assmbly

[18Fiatsandcounting]

Pdr1966 is correct: Usually the problem lies with poor grounding connections and corrosion or loose connections on the circuit board for the taillights. Correcting all that can make a big difference.

-Bryan

[spider2081]

Note the twilight PCB are remove from the housing easily by releasing snap clips, you do not need to dismount the twilight assmbly

Does a 1977 Spider have tail light printed circuit boards?? I'm pretty sure the 1979 and after do but not sure if a 1977 has them.
At any rate the tail light ground is often made near the driver side tail light assembly Using a tail light assembly mounting stud. These ground connections are quite temperamental and often create unusual lighting issues.

[dinghyguy]

Just a note: there is corrosion under the sockets that are riveted to the PCB. I have found that drilling out the rivets, cleaning the base and the PCB, putting on a bit of dielectric grease and bolting all back together with some small nuts and bolts in place of the rivets addresses the corrosion. I clean the base bottom and inside using a brass wire wheel on a dremel.
I and my fiat friends have done 4 sets of PCB's this way and all works as intended afterwards.

cheers
dinghyguy

[18Fiatsandcounting]

Does a 1977 Spider have tail light printed circuit boards?? I'm pretty sure the 1979 and after do but not sure if a 1977 has them.

The printed circuit boards started in 1979, so earlier cars had the bulbs screwed into sockets riveted to the light assembly. The grounding for these was, in a word, lame. Inconsistent taillight grounding is the source of many issues.

-Bryan