Headlight and Parking lights Inop

[LTZ C20]

My headlights and parking lights don't work at all. I just put headers on the truck and had the front half of the exhaust rebuilt to meet the headers. If I pull the headlight switch out 1 click for parking lights or 2 for head and parking lights none of them come on. My interior dome light and cigarette lighter plug and dash lights also don't work. My blinkers, hazards, brake lights all work fine.  I checked all my fuses and even switched each fuse with a new one individually. I have also replaced the head light switch thinking it was the problem. The lights still don't work. I even cut the fuseable link out down by the starter and just connected the wiring without a fuaseable link, still no lights. If i activate my alarm, my parking lights will flash to acknowledge alarm activated and the will flash again to acknowledge alarm deactivated if I turn the alarm off. I'm so confused and I need my truck and I cant drive it home from work so I have to get a ride becuase its dark when I get off work. this is very frustrating.

[bd]

Did you check the fuse link at the firewall junction block?  Also, check the red 10/12 gauge wires at the firewall bulkhead connector to see if power is feeding through the connector into the cab.

[LTZ C20]

I checked all the fuses if that's what you mean? I'm not sure what you mean?

[bd]

There often is a second fusible link at a firewall mounted junction block located above the left valve cover.

Power feeding into the cab is carried on the heavy, 10- or 12-gauge red wires that pass through the bulkhead connector.  One of those red wires feeds the headlamp switch.  A better way to ask the question is, Did you verify power to the headlamp switch on the red wire when you replaced it?

[LTZ C20]

I'm not sure if I have power to the switch. I used my multimeter. I put it on 20 volt DC current, touched the red probe to the hot red power wire and the black probe to the ground on the headlight plug terminals, nothing happened. I put my multimeter on continuity, I touched the red probe to the ground terminal plug and the black probe to bare metal and I have continuity thru ground. I put the red probe on the hot red power wire and the black probe to bare metal and i have continuity from power to ground also. So I'm not sure if I have power to the switch or if something is shorted.

I also heard that the headlight low beam/high beam dimmer switch can cause all the lights not to work, is this true?

I thought maybe the new headers and exhaust work might cause a problem but I can't find anything that doesn't look normal, i"m not finding and stray or damaged wires under the truck.

[bd]

Check for battery power on the heavy gauge red wires as they enter the bulkhead connector at the firewall.  All of the large red wires should be hot.  If they are not all hot, trace them through the engine compartment to find a melted fusible link, or bad connection, or damaged wire.  If they are hot, then check for battery power on the red wire at the headlamp switch.  Because of the nature of your electrical problem, a test light will serve you better than a voltmeter when checking for power.

IMO, it is too coincidental that your lights worked before the exhaust work, but not after.  My initial inclination is that the harness was inadvertently pinched or damaged by torch or spatter during exhaust installation.   Hopefully you will find it with some patient inspection and methodical testing.  Keep us apprised and we will do what we can to help.

[bake74]

I'm not sure if I have power to the switch. I used my multimeter. I put it on 20 volt DC current, touched the red probe to the hot red power wire and the black probe to the ground on the headlight plug terminals, nothing happened. I put my multimeter on continuity, I touched the red probe to the ground terminal plug and the black probe to bare metal and I have continuity thru ground. I put the red probe on the hot red power wire and the black probe to bare metal and i have continuity from power to ground also. So I'm not sure if I have power to the switch or if something is shorted.

     You are suppose to have power there, trace down the fuse able link BD suggested and see if you lost power there.
     Do you have a wiring diagram you can follow from the switch back to see where you are loosing power ?

http://forum.73-87chevytrucks.com/smforum/index.php/topic,11766.msg87585.html#msg87585

[LTZ C20]

I will have to get a test light to try that. I do have wiring diagrams also yes. I found a little too coincidental also that they worked before and not after. I'm guessing that the bulkhead connector is the same thing as the engine compartment backside of the fuse block?

[bd]

...I'm guessing that the bulkhead connector is the same thing as the engine compartment backside of the fuse block?

That is correct.  However, the fuse box is not actually 'part' of the connector.  They just piggyback one another and attach to the firewall with the same two screws.

[LTZ C20]

Ok. I will remember this and check it out as soon as I can to work tomorrow where my truck is. I'll keep this updated as to what I find. Thanks bd!

[LTZ C20]

Ok, so here's an update, my lights are working again. Friday night I was trying to get them work, I decided to make a temporary hot wire with and inline fuse to power the switch until I found the problem. Well I wasn't even touching the truck, I was making a piece of wire with connectors and my door was open. I looked up and saw the dome light on. I was surprised so I hurriedly grabbed the headlight harness, plugged it into the switch and turn the lights on. They worked. I put the dash back together, and drove over speed bulbs at about 15 20 mph and they kept working. They have been working all weekend and are nice and bright and my dash lights and done light are brighter also, (prob due to the new switch with better connections inside the switch). So for now they are working well and I'm not sure what happened. I guess I will see down the road if something changes.

[pholliday1]

Ahhhh the gremlins they are busy creatures. Glad you got it figured out.