Lighting Help

[alf1096]

I have just bought a 70 stepside. The person I bought it from put 47 chevy led's in the bed. During the day the the leds work perfect!!! The lighting problem starts when I pull the knob out for the running lights the whole back end of the truck goes dark. I turn the lights off and I have lights again. I already checked the ground and they are good. I got all the lights to work twice but the minute I turn them off and then back on I have the problem again. Has anyone had a problem like this. Could the switch be bad? If the switch is bad would that keep the front lights from comming on also

Thanks for the help

kody

[Sweet72]

Not sure what you're referring to when you say "running lights" maybe parking lights? but I suspect you have a grounding issue whether it's a bad ground at the rear lighting harness, or the bed-to-frame bonding wires are not installed. A poor (corroded) connection somewhere in the rear lighting harness may be the culprit. Make sure the engine is bonded to the cab, cab is bonded to the frame, and bed to the frame.

[alf1096]

You are right I did mean parking lamps. Would it be the ground if the brake and turn signals work all the time but when I turn the parking lamps on. It looks like to me that all the grounding for the lights is done in the same place... inside the parking lamps to the body.


thnaks

kody

[alf1096]

I got a chance to look at it this morning and it does the same thing. But every time I shake the bed the lights will come on. I think it is a grounding problem with the bed to the frame. What would be best to fix the problem. Move the grounds to the frame or ground the frame to the bed.

thanks

kody

[Longhorn Man]

I'd lean more towards the brown wire being messed up instead of the ground. The fact that the higher amperage brake lights and turn signlas work tell me the grounds are fine.

[Sweet72]

Yep, you shake the bed and the lights work so it's a ground prob. You can buy a ground strap kit from one of the vendors or make your own using 10 ga automotive wire and terminal lugs, and make sure they're installed to bare metal, tight, and use dielectric grease between the terminals and frame/bed to prevent further corrosion. To put it in electricians terms... make everything on the chassis at the same electrical potential.

[Longhorn Man]

sweet72, how is it the brake lights work with a bad ground?
They are grounded to the same ground as the tail lights are, so if the higher amp component is grounded, then the lower amp component hooked to the same ground would be good.
This is basic electrical stuff like I do every day at work.

I'm willing to be a kick in the jimmys that the brown wire is damaged somewhere. Start with under the bumper in the center...where the harness has been chopped several times over the years for trailer harnesses. You are looking at the brown wire, this is the one that powers the parking lights, lic plate lamp, and the side markers. If it looks good there, then follow the harness to the cab, looking at the brown wire all the way up. You're looking for where the wire has been pinched or crushed, or maybe where some one had poked it with an electrical tester and didn't seal it. You'd see this as a blob of green corrosion and it'll look swollen.

[alf1096]

I fixed it!!!! All I did was run a 8 inch wire from the bed to the frame and it works now I cant explain it either.

[Longhorn Man]

looks like I'm getting kicked in the daddy parts.
Keep an eye on your side marker lights in your mirrors... cuz what happened makes NO sence at all.

[Sweet72]

Andy, I'm not challenging you by any means, and I also do this sort of thing everyday on my job. I understand why you think that if the brake and turn signal lights work then why does everything go dark when he pulls the lights switch out? I'd be willing to bet the brake and turn signal lights weren't full bright either indicating a high resistance ground which when a larger load is applied ie: tail, side marker and 47 LED lights that the ground provided by those rusty carriage bolts holding the bed to the frame won't be sufficient for the current to flow to the additional loads. I'll bet a paycheck that all the lights were illuminated very very dim. It's like having 51 sprinklers hooked up to your garden hose and opening valves to only 4, they'll probably work ok, but when you open the other 47 valves the volume and pressure at each sprinkler will drop drastically. That's why good clean grounds are so important in a circuit.

[acloco]

I will vote with Sweet72 as well.....it was a backfeed...finding ground in one of the other circuits.

alf1096 - check the rest of your grounds on that truck......this is a preclude of things to come!

[FRENCHBLUE72]

I have been having problems with my rear leds also have a back feed problem in the emergency flasher part of the system .... Gonna install the painless kit this weekend..