Need electrical help - turn signal / park lamp

[68bowtie]

Been trying to troubleshoot this and can’t quite figure it out. 1970 chevy driver side turn signal/park lamp won’t light up at all as a turn signal and will only light up slightly (very dim) as a parking lamp.

Details:

- New bulb works (tested on other side)
- Turn signal and hazard flashers both working
- When I turn on the hazard lights the pass side flashes bright, driver side flashes very dim, both dash green lights flash, and both tail lamps work fine
- On the wiring diagram these are pretty much two separate circuits so I figured it’s a ground problem, so I removed the housing and wire brushed the contact points with the grille and inside the socket and no change.
- hooked a test light inside the socket and I get a light when parking lights are on but nothing for turn signals.

Wondering if anyone has any ideas???

Does the flasher circuit use the turn signal or park lamp wire? I suppose I can check that with my light...

[dmjlambert]

I suggest attach a wire, from the negative battery post to the parking light housing and see what it acts like then. Perhaps you can use a jumper cable.

If the problem is on the positive wire side, I've highlighted the path in yellow marker, it goes from the flasher module at the bottom of the fuse panel on the purple wire, into the turn signal switch on the steering column and then comes back out (if the blinker switch is pressed down) through the light blue wire and goes through the firewall connector to the brighter of the 2 filaments inside the bulb. So check with a multimeter or light-up voltage tester that you have 12V on both the brown and light blue wires at the steering column connector. If you don't have the 12V coming out of the column on that blue wire when the turn signal is switched for left blinker, then you may have a bad turn signal switch. If you have 12V on the light blue wire, check for voltage further along the wire, such as at the firewall connector, and at the connector on the radiator support.



A tester like one of these is handy.


Full wiring without my highlighting is here:
http://67-72chevytrucks.com/vboard/s...&postcount=302

[68bowtie]

This is fantastic I will report back thanks!

[68bowtie]

Ran a wire from negative battery terminal to the bulb socket and bingo. Then contacted the socket to housing and bingo again. Removed the housing assembly and gave the socket a few turns in the housing. The socket is still tight in the housing but it loosened up whatever corrosion was between there, reinstalled and everything is functional. Not sure how long it will last but at least I know where the problem was/is. Thanks again for the tip!

[dmjlambert]

I had a license plate light assembly that would not conduct from the socket to the housing to the bumper no matter what I tried. I even cleaned up and could see with my own eyes bare metal surfaces touching together, and it would not work. I ended up running a wire from the bulb socket to the bumper and it worked and got me through inspection. I eventually replaced the assembly. Sometimes I don't know what the deal is with grounds, and they are a mystery, but I know they are important.