It’s always a grounding issue, but...

[hopsedge]

So, my right front blinker on ‘67 SV was the only exterior light not working properly, not working at all actually. Assumed it was a grounding issue, and that the mounting screws for the turn signal/ running lamp housing were not making good contact through the spring clips. So I ran a dedicated ground wire from one of the mounting screws to a good solid bolt that coincidentally was also being used to ground a PO’s new running light on the same side. The running lamp worked fine before and still works fine now.

I thought for about 6 hrs that this fixed my blinker problem, but no. I swear it worked during a brief test, but it’s not working now. I’ve checked the connections & they’re tight. The new strange thing is that now not only does the right front blinker not work, but the tach needle jumps when I toggle the blinker arm on the steering the column to engage the right blinker. I did nothing at all on the column or under the dash.

So I guess my question might be: Can you have too many grounds, and can they somehow feedback on one another to cause weird new problems that didn’t exist before?

The other thing I should mention is that I have no panel/instrument lights. This was the case before I grounded the right front blinker & it remains the case now. Thought I would fix one and then the other, but...

 

[sunalp]

Short answer is that no you can't have too many grounds. From what you have described, you don't have the
panel lights grounded. The turn signal/parking light may also be caused by corrosion inside the housing
where the bulbs are installed. There are areas in there where they actually fall apart. I think they were kind
of fragile even when they were new.

Check the daisy chain ground on the gauges, connect a ground to it if it doesn't have one. It has to ground to
the body somewhere. Also, check your bulbs and bulb holders. The grounding may also effect the tach too.

Hope that helps, I'm sure others will chime in as these are common issues with these cars.

Cheers!
Steve

 

[Tim R]

We add multiple extra earth wires to our cars. We put in wired grounds for each side light and indicator unit (we don't like self tapping screws damaging the paint to make an earth, so we fix the side light units on with stainless nuts and bolts), we have a thick earth wire that runs all cross behind the dashboard with spurs coming off it for the instruments and also put additional wires to gearbox and engine from the chassis. Much like increasing the thickness of the wires to the headlights and horns you get immediate benefits for minimal effort.

Tim R

 

[jumpinjan]

I'm doing an installation of the front signal lights and I also recommend to make the grounding wire. However, I do not recommend WD40 as a contact cleaner/lube on electrical connections. The proper product to use is something like "Deoxit". Everyone uses Deoxit on any electrical switching or contacting application, and I use it on all my electrical restorations to include vintage radio power switches, rotary band switches, pots and so on.
Jan
https://caig.com/product/deoxit-d100l-2db/

 

[Tom H]

That tach needle jumping may be a clue. Something is mis-wired. The only reason the tach needle would jump is if a pulse of current passed thru the loop of wire on the back of the tach. And that wire should go only to the ignition coil. It sounds to me that somehow that wire is connected to the turn signal circuit. But then no panel or instrument lights may indicate other wiring errors. Does the tach read the RPM when running?