Another Electrical Issue Question

[sdmahr]

Problem: No drivers side parking light, running light, or brake light in the rear. Turn signal will attempt to blink, but dies with a dimly lit light. I verified there is NO short to ground from the tail-light socket up to where it connects through the firewall. From the INSIDE of the firewall up to the switch, I checked from the end of the connector to ground and two of the 4 pins ARE grounded with the switch off. Is that normal? I did have a blown fuse in the fuse box and I replaced it and now it exhibits the symptoms above.

I checked the wire harness from the inside of the firewall up to the headlight switch and don't see any abrasions or burning. I'm thinking headlight switch as they are a constant complaint here.....any other suggestions?

[truckdude239]

well on our trucks as old as they are it sonds like grounds i'd try removing the grounjds and sanding them and the metal behind them if thats not it i'd try the the headlight swtich but what sounds like is happing is that you got a hot wire grounding out with power on. i check the back of the head light switch because the park lights and brake lights on these trucks DO run tough the turn signal well that be the frist i check. i had an 1987 ford f-150 do the same thing after i took the steering columon apartand put it back together i ended up replacing the turnsignal switch. to check the ground you could try the 4 ways and see if they work? if the lights light up with 4 ways your ground are good and you left with turn signal or head light switch

hope that helps

[Longhorn Man]

I agree on the ground here, but it won't be the headlight switch... since the parking lights are working in the other 3 positions, then the switch is doing it's job.
First however, look under the bumper, see if there is a wire mess where ppl have installed trailer light harness plugs in the past. If it all looks good, then look for a cut/pinched wire...the brown is the parking light wire, and the I think yellow is for the right brake/turn signal. (If not yellow, then green)

[motocrosschump]

had the same problem, my fix was replacing the HOT wire going inside the cab.

[Longhorn Man]

Which hot wire are you refering to? The main one to the fuse box?

[69TowRig]

I had a problem recently with my rear lights, no brake lights or right rear turn signal. Turned out that the dash connector was not making good contact. I pulled it loose, cleaned it, dielectric greased it, plugged back in. Now everything is great!

I had to patch my rear body harness in 3 places before all was well back there, it was tapped into that many times for trailer harnesses! The Yellow is the left, the Dark Green is the right, Brown is running lights, Light Green is reverse lighting.

[sdmahr]

OK, problem solved ! For those who guessed bad ground....good job !

My 69' is a step side. So the tail lights are bolted to the bed via two bolts on each bracket to the bed. Seems like the bolted on bracket was making the "connection" therefore the problem. I checked all the wiring and connectors and everything was OK. I had voltage to the bulb contacts so I knew something was up....and the only thing missing was the ground to complete the circuit. Funny though when I checked earlier this week I had the ohm-meter grounded on the light housing and touching the bulb contacts with no voltage present....guess now I know why ! Once I put the ohm-meter black lead on the bumper and then touched the bulb contacts I got a good voltage reading.....leading me to figure out the light housing wasn't well grounded.

Shoot...whooda thunk it !!

[Longhorn Man]

Ground issues are common on these old vehicles, but even more common on trucks with wooden bed floors.

[purple gas]

My truck has a steel floor and I still had ground problems. I ran a wire from the frame to the box ( I'm Canadian , eh) and that was the final step to getting my tail lights working