No Brake/Tail/Rear Side Marker/Front Parking Lights

[72ChevyRock]

I have a 72 Long Bed and recently my front parking lights, panel lights, tail lights, break lights, and rear side marker lights have gone out (It keeps blowing the 20A "Tail Stop" fuse). I've placed a test light on the wires that go to the brake switch and I get nothing. According to the schematic I have, it says that the orange wire is constantly hot and the white wire goes to the "convenience center."

I tested the headlight switch and everything checks out. When I put a new fuse in the fuse box it blows as soon as I pull the headlight switch out (in either position). Just to be sure, I bought a new headlight switch. GOOD NEWS: my hazard lights do work (that's what confuses me). When I put the hazards on, my front parking lights and rear tail lights blink as they are supposed to, but they don't work when I turn on the headlight switch (fuse blows quickly).

Needless to say, I have to drive everywhere with my hazard lights on because I have no tail lights and no break lights.

Any ideas?

[Longhorn Man]

something in the parking light circuit is shorting to ground.
First place to look is under the rear bumper where previouse hillbillies have hacked in trailer harnesses 12 times. The brown wire is the one you need to look at real good.

[72ChevyRock]

I will check it out. On this one, I had the bumper taken off and welded a roll pan in. I will put a test light to the brown wires from the side marker lights and I'll follow it back until I can find out what's going on. Would the parking light circuit prevent power from going to the brake switch? I tested the line coming from the fuse box to the brake switch and I get no juice. I thought that was odd.

[Longhorn Man]

that fuse controlls the dome light, brake lights, parking lights and dash lights

A test light won't do you any good, if you turn on the lights, and the fuse goes, it'll be dead by the time you get to the back of the truck. Do a visual check first, look for something pinched, broken, green/corroded, or swollen.

[Blue85]

insulation burnt off the wires while welding on the roll pan mabye?

[72ChevyRock]

Never thoughts of that. I actually had the roll pan welded in last May and I suppose that something could've happened between then and now.

[72lb4x4]

There is (or once was) a rubber connector (looks a bit like a big grommet) at the crossmember way in the back of the truck. This connects the harness that goes from the firewall to the crossmember to the lights in the back of the truck. If its still there, unplug it and see if the fuse still blows, or if the brown wire is almost zero ohms to a good ground. To ohm it out, you need to remove the tail and marker bulbs, since their resistance is low.

Mine was blowing the same fuse until I found one of the cheesey aftermarket park lights was shorting. Now I have a dome light. I also have one tail light, one marker light, license light, and a brake light on when the parking lights are on.

This doesn't sound like much, but its an improvement...

[onetonk5]

mine was as simple as the tag light plug was undone(by me) and a Small amount of copper was left sticking out the end of the rubber .......bounce around a little and it grounded out on the backside of my bumper....Found out the problem after Djracer and I had made a High Speed run to FedEx near closing time. Sounds like you have a wire chaffing issue to me..good luck.

[72ChevyRock]

My rubber connector/grommet is still intact. I'll have to see if it blows the fuse after I unhook it. If the brown wire is almost zero ohms, then I have a good ground? What is the qualifier that makes the ohms nill for a good ground? I mean if it is over a certain amount, what is the cut-off that would clue me in that my ground is bad?

As for my tag lights, I actually replaced it after I had this problem thinking that was the problem. They needed to be replaced anyway (pretty ratty wires).

I really appreciate all of the suggestions I've had from the folks on this forum. Thanks guys.

[72lb4x4]

On the brown wire (on the tail light side) with no bulbs, and the crossmember connector unhooked, you should have infinite resistance (ohms). If the resistance is low, then chances are the short is in the wiring for the taillights.

A bad ground would cause the lights not to work. Since the fuse is blowing something is grounded that shouldn't be.

I made things more complicated, sorry.

[72ChevyRock]

Well, I just unplugged the crossmember connecter and the fuse still blows. That tells me the brown wire must be grounding out somewhere between that point and the fuse box right? What about the front parking lamps? Any guidance would be greatly appreciated.

Thanks,

Clint

[5150]

Check your turn signal switch. I had the same problem. Pull off your steering wheel and loosen the turn signal switch screws (3) and then try your lights again. I had the same problem for some reason so I backed the screws out a little and walla.

[72ChevyRock]

Well guys, while I was looking for this problem something else happened to me; my alternater went bad. That just about completes my entirely new ignition and charging system. New starter, alternator, battery, ignition switch, HEI coil, and key cylinder.

**PROBLEM FOUND: It turns out that it was my parking lamps that was making my fuse blow out. What stumped me was that my hazard lights still blinked in the front and I guess I couldn't realize why that would be the problem for my running lights. I thought it would all be in the same circuirt. Oh well, I learn new stuff every day. Does anyone know where I can get used/new running lamps for cheap? Also, I am considering the sale of this vehicle as I have no time to play with it anymore. My needs and focus have now shifted more to my family as my daughter is getting older. I must now look for a newer vehicle that my wife will actually drive if necessary. Thanks again guys for your help.