What the....? No headlights!

[Darrman]

Ok, I am finally installing the front end back on my truck after being apart for a couple years. Everything was going great until I try the headlights and get nothing.
Here is a list of what I have done...
New headlight switch
New dimmer switch
New Dash e-flasher switch (moved from glove box)
New headlights
New park/turn bulbs
New rear bulbs

And here are the symptoms...
Pull the switch to just the parking lights, all parking lights work, front and back
Pull the switch to headlights/parking lights, no headlights, no front parking lights, rear lights work
Pull the E-flasher switch, works no matter what the headlights are doing
Turn signals work no matter what the headlights are doing
Rest of the headlight switch works great, dome and dimmer.

So I have taken a tester light to the harness at the bulb and get nothing while the headlights are on. I also tested the grounding screw, getting a good solid ground. The headlights DID work before I took everything apart, but its been a long time since then
So all that said, anybody have a idea what could be the problem? I will start checking wires tonite to see if I can find anything.
Thanks for any help!

[kaptnkaos]

Hey Darrman,

What year truck are you workin' on?
'67-69 the front marker / running lights do turn off when you turn on the headlights.
If the headlights worked before the tear down, you might have a bad switch (yes even new ones can be bad.)
I'd try the old one... something else you might check is the headlight fuse...
The next step would be chasin' wires...

KaptnKA S

[fordman]

look at the wiring diagrams for your year of truck or wiring harness. look at the switch wiring find the wire for only the headlights. see if it has power coming out to the headlights when the switch is on. follow that wire up to the headlights and see where the power drops out. or where the power ends at. also check your fuses and fuse holder inside of the fuse box. make sure the fuse is good by removing it and inspecting it. that will let you see the fuse holder while the fuse is out. also check the power from the fuse box to the headlight switch headlight wiring. it could be the switch has a interanl problem even though it is new.

[warponyxlt]

dimmer switch wire plug in check the wires

[Thunderfoot]

something else you might check is the headlight fuse...

also check your fuses and fuse holder inside of the fuse box. make sure the fuse is good by removing it and inspecting it. that will let you see the fuse holder while the fuse is out. also check the power from the fuse box to the headlight switch headlight wiring. it could be the switch has a internal problem even though it is new.

FYI,
The Headlight/Park lights are NOT fused, so there is no fuse in the fuse box for them, the light switch has a built in circuit breaker

To check the light switch, check the Red/yellow stripped wire for power out with the headlights on. Check this at the light switch and at the High/low beam switch on the floor... Then check for power out of the High/Low beam switch.

[kaptnkaos]

duh

Dang Thunderfoot, I even knew that... How come there isn't a smiley for kickin' yer own butt ???

KaptnKA S

[fordman]

sorry it was 3:00 am when i posted that. i didnt go look at a fuse block or diagrams to check. i knew about the circut breaker thing. but it was early in the morning.

[Darrman]

Sorry I guess it would help to mention its a '69 F100. I have double checked for obvious wire problems, everything seems to be in good shape. Next I will track down the headlight wires for testing.
I forgot all about the front parking lights not working with the headlights, now I remember finding out this wonderful fact when I first got the truck. What is up with that, a power saving thing or what? Is there a way to make the parking lights work with the headlights? I just dont want the local fuzz on my ass everytime I drive around at night, which around here is sure to happen.
Thanks!

[fordman]

the parkign lights are suppose to go out when the headlights come on. the parking lights have the first positon click whenthe headlight switch is pulled out. the second click or postion is for headlights only. but that can be changed if it is desired to have the headlights and parking lights on at the same time. just move the parking light wire to the headlight wire as it leaves the switch via a jumper wire.

[Darrman]

Well I found the red/yellow wire, tested it at the headlight switch, got a good signal with the headlights on. However at the other end of the wire, at the dimmer switch, there is nothing at any of the wires there. So I guess this would be my problem.
I traced the wire and everything looks good except where it is bolted to the firewall for some reason. I cant see because it is under my brand new firewall cover, and held down tight by the parking brake that was a pain in the ass to install. I do not want to have to undo these things

[Thunderfoot]

Well I found the red/yellow wire, tested it at the headlight switch, got a good signal with the headlights on. However at the other end of the wire, at the dimmer switch, there is nothing at any of the wires there. So I guess this would be my problem.
I traced the wire and everything looks good except where it is bolted to the firewall for some reason. I cant see because it is under my brand new firewall cover, and held down tight by the parking brake that was a pain in the ass to install. I do not want to have to undo these things

Sounds like maybe the parking brake has the wire pinched... looks like you're on track.

Is there a way to make the parking lights work with the headlights?

On the Back of the Light switch you want to unhook the Black/Yellow striped wire and hook it in with the Brown wire (or jumper the wires together). Ford changed this wiring in 1970 to be like this so that the front park lights would stay on with the headlights.
FYI, the Black/Yellow striped wire is the front marker light wire, and the Brown wire is the rear tail light wire...



kaptnkaos & Fordman, all's

[67MercM100]

Hmmm...
Yep, it would have to be the wire from the headlight switch to the dimmer switch.

Just to ask: How did you check at the dimmer switch? I've been working on a similar situation. The center contact should be the "hot" one at the dimmer. Thankfully I had power there. To test, I jumped across the connector at the dimmer with a paper clip. That gave me lights.

Perhaps you could jump a known good hot wire to one of the side terminals on the dimmer connector just to make sure they'll come on when powered from that point. Also, I know I've done stupid things like: tested without the headlight swich pulled out; not double-checked for a good ground on my test light. I'm not saying you did that; I'm just saying I'd double-check before undoing stuff that was a pain to do.

[Darrman]

Success! Had to dig between the parking brake and the wall, but found a big gash in the wires going down to the dimmer, looks like the welder accidentaly nicked them while cutting something. It only cut the red/yellow, so when I got a butt connecter in there, it got the headlights fixed right up.
Feeling very relieved right now
Thanks to everybody for helping me figure this one out!
BTW I was using just a simple light indicator type tester, ground and touch that kind of thing, mine does ground and hot, Walmart $5 I think.

[fordman]

Hmmm...
Yep, it would have to be the wire from the headlight switch to the dimmer switch.

Just to ask: How did you check at the dimmer switch? I've been working on a similar situation. The center contact should be the "hot" one at the dimmer. Thankfully I had power there. To test, I jumped across the connector at the dimmer with a paper clip. That gave me lights.

Perhaps you could jump a known good hot wire to one of the side terminals on the dimmer connector just to make sure they'll come on when powered from that point. Also, I know I've done stupid things like: tested without the headlight swich pulled out; not double-checked for a good ground on my test light. I'm not saying you did that; I'm just saying I'd double-check before undoing stuff that was a pain to do.

sometimes on a non rebuilt truck that has seen many days that it was used while raining and or at night. the dimmer switch can get rusty and stick while driving and make the lights go out when you depress the dimmer switch. taking off and cleaning the shft of the dimmer switch can sometimes fix the rusty sticky dimmer switch or replacing the dimmer switch will fix a bad one that sticks also.

[warponyxlt]

the dimmer can also make the lights blink off an on to that sucks at night in the rain with a car coming that is something that old trucks do when a guy puts off repairs