Side Marker/Parking Light Issue

[Sir Psycho C10]

Happy Holiday's Everyone. First post for me. Got a unique one here. Got a 72 C10 with electrical Gremlins. Prior to the engine/trans swap all electrical was functioning as designed. Today is a different story. Here we go....

With the parking lights on (switch 1/2 way out) I have lights, except for the right side front marker and right side front bumper light....BUT, when I put on the right side turn signal OR hazards they blink....so I know they work. They are getting power from the column just not the headlight switch. Installed new headlight switch prior to the swap.

The left side will blink together with parking lights on and alternate with headlights on (or vice versa). The right side will blink together only with turn signal or hazard.

Something tells me my issue is under the hood. They eliminated a TON of wires with the swap. Can someone verify what color wires you have going to each side and where it terminates at the firewall. I think I have 2 wires on the left side and only 1 on the right side?

Thanks for your time, Jim

[FLcustom10]

Whenever you have strange electrical problems the first thing to check is grounding straps. Here is one thread on grounding strap locations. There may be others:

http://67-72chevytrucks.com/vboard/s...d.php?t=509265

[FLcustom10]

It looks like I have blue and brown wire for the parking lights:

[VetteVet]

here is a wiring diagram that shows the lights on our trucks. The light blue and brown wires power the left park/turn/lights and the dark blue and brown wires run the right park/turn/lights.
The markers have brown and black wires to power them.

The markers and turns are on the right side upper half of the diagram.

[Sir Psycho C10]

Thanks Guys, we should have light shortly and I'll get back under the hood to verify.

VetteVet - is that diagram for a 72? I have another diagram and the colors contradict. Just want to make sure prior to gutting it. I don't think I have a brown wire running over to the right side....and it looks like the brown is power from the headlight switch.

[D.PASSMORE]

I used this diagram to solve a eletrical problem with front parking lights and blinkers. I circled where the problem was for my issue. The LED bulbs that I was converting too did not supply that ground and caused similar symptoms that you mentioned. So, ensure you have a good 12V flow to positive side and ensure that you have good grounds. I used a pick type light tester to troubleshhoot.

[Sir Psycho C10]

SUCCESS!!! I am back in business. The brown wire was removed/missing on the right side after the engine swap. I spliced into the left side and everything works as designed. Thanks for your responses....this site is the best.

Jim

[1972RedNeck]

It is impossible to have too many grounds.

[228anthony]

i am having similar issues.
with the car off and the lights on ,only my driver side front marker comes on but none of the others. with the car running only the passenger side works as it should. i need help!!!

[Big Kev-O]

Originally Posted by 1972RedNeck

It is impossible to have too many grounds.

No, you can add grounds until your truck looks like spaghetti if you like. What is most inportant is that you have a good ground connecting the battery to the engine block, frame and cab. I run a 4 gauge from battery to block and frame then ground the cab to the frame with 6 gauge. That should be plenty sufficient. Too much ground is not an issue.

[cdowns]

each and every light bulb needs to b grounded in order for them to work properly it's alot more to grouding than a handfull of wires

[228anthony]

Alright !!!! thanks for all the help guys , i searched and researched and found that I had some ground wires crossed that had coroded. chenged them out and BOOM!!!! lights all work as they should.