It's gotta be the headlight switch right?

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salami340

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ok so I did some searching on the forums and I can't seem to find any similar situation to what i am experiancing. So two weeks ago the first click on the headlight switch stopped functioning. No marker lights/dash lights/tail lights. So I assumed the switch went bad so i ordered a cheap generic one on ebay. I get the new one and the lights flash but go out before the first click. Oh and the headlights go on with the second click like they should. So i order another oem switch this time and still no lights. At this point i think it is not the switch so i start checking wires, everything looks ok. Next thing was i manually connected the black wire plug on the headlight switch connecter to the yellow/black plug on the connector and the lights switch on... Its gotta be the headlight switch right!? I also tried another old switch from another instrument cluster i had with the same issue. I'm stumped. Hopefully someone has seen this before.

The vehicle is a 1975 duster.
 
You may have a bad, loose, or corroded connection at the brass connector in harness at switch. Remove female spade connector from its plastic housing, and examine. This area of harness sees a lot of moisture from wet feet over the years, and if you live in the snow belt, a that switch has seen a lot of salty water which is very corrosive to brass & copper.
 
Could be just a blown fuse. Find the one fuse that doesn't have power on either end. When the headlight switch is pulled to the first click at least one end of that fuse gets power. If one end is hot and other is not, replace the fuse.
 
Had a situation with NO brake lights, checked everything, switch wiring, turned out to be a bit of corrosion on the ends of the glass fuses where breaking contact in the fuse panel. Removed & cleaned the fuses & all is good to go.
 
I checked all the fuses with a voltmeter on each end. Everyone reads fine. I really thought it was a bad headlight switch but I've tried 3 different switches, 2 new and 1 old, and none work.

Since I can jump the plug connector for the headlight switch with a piece of wire and the lights turn on then I don't see what else it could be other than the switch...
 
I did the same thing, checked them all in the fuse panel with a meter. Was not until I took them out 1 at a time I found the issue.
 
You keep talking about "the lights"

The headlights work?

The marker / tail lights do not? Would you confirm that?

Do the dash lights work?

Jumpering from the BLACK wire is INCORRECT.

There are TWO power sources TO the light switch

I don't have a shop manual for a 75, only a 74. But there are somewhat useable diagrams here:

http://www.mymopar.com/index.php?pid=31

http://www.mymopar.com/downloads/1975/75ValiantA.jpg

http://www.mymopar.com/downloads/1975/75ValiantB.jpg

Look at the bottom right of diagram "B" and find the light switch. Find the black, top left of switch, and follow it off the left of the page.

Continue it on the right side of diagram "A" NOTICE that it splices into the BIG BLACK wire which is the black ammeter wire. This IS the factory "in harness" splice and is located a few inches down the harness from the ammeter black ring connector. It supplies ONLY the headlights, NOT the tail/ park/ dash lights

TAIL/ MARKER LIGHT (and DASH) power comes from the PINK. Look again on diagram "B", and find the pink wire on the light switch, (second terminal from bottom right) and follow it way up and off the left of the page, continuing on diagram "A" (third wire from top right) It goes to the FUSE

DASH LIGHTS. These are a trick. The dash light dimmer control gets power inside the switch from this same PINK wire, BUT the OUTPUT of the dash light dimmer comes OUT of the switch on a TAN wire, goes to the FUSE PANEL and feeds TO one lonely fuse, the "inst" fuse, and then feeds off to all the dimmer controlled dash lamps on ORANGE wiring. You can see that by looking at the fuse panel, top right of diagram "A", and the single fuse at top right. notice the TAN and ORANGE wires. NEITHER of these will show power UNLESS

1 The tail lamp fuse is good, and 2 the light switch is either in "tail" or "head." This is the only fuse in the car that operates in this fashion

According to my 74 manual, which may or may not be the same as '75, the inst. lamp fuse (3A) is cavity 1, the MAIN FUSE you need to be worried about is cavity 8, at the other end. This is a 20A fuse and feeds HORN and RELAY, provides power for INST lamps, TAIL, LICENSE, SIDE MARKERS, and PARKING

If you do not have good power to that last fuse, you won't have power to the light switch for the tail/ markers/ dash and parking.
 
You keep talking about "the lights"

The headlights work?

The marker / tail lights do not? Would you confirm that?

Do the dash lights work?

Jumpering from the BLACK wire is INCORRECT.

There are TWO power sources TO the light switch

I don't have a shop manual for a 75, only a 74. But there are somewhat useable diagrams here:

http://www.mymopar.com/index.php?pid=31

http://www.mymopar.com/downloads/1975/75ValiantA.jpg

http://www.mymopar.com/downloads/1975/75ValiantB.jpg

Look at the bottom right of diagram "B" and find the light switch. Find the black, top left of switch, and follow it off the left of the page.

Continue it on the right side of diagram "A" NOTICE that it splices into the BIG BLACK wire which is the black ammeter wire. This IS the factory "in harness" splice and is located a few inches down the harness from the ammeter black ring connector. It supplies ONLY the headlights, NOT the tail/ park/ dash lights

TAIL/ MARKER LIGHT (and DASH) power comes from the PINK. Look again on diagram "B", and find the pink wire on the light switch, (second terminal from bottom right) and follow it way up and off the left of the page, continuing on diagram "A" (third wire from top right) It goes to the FUSE

DASH LIGHTS. These are a trick. The dash light dimmer control gets power inside the switch from this same PINK wire, BUT the OUTPUT of the dash light dimmer comes OUT of the switch on a TAN wire, goes to the FUSE PANEL and feeds TO one lonely fuse, the "inst" fuse, and then feeds off to all the dimmer controlled dash lamps on ORANGE wiring. You can see that by looking at the fuse panel, top right of diagram "A", and the single fuse at top right. notice the TAN and ORANGE wires. NEITHER of these will show power UNLESS

1 The tail lamp fuse is good, and 2 the light switch is either in "tail" or "head." This is the only fuse in the car that operates in this fashion

According to my 74 manual, which may or may not be the same as '75, the inst. lamp fuse (3A) is cavity 1, the MAIN FUSE you need to be worried about is cavity 8, at the other end. This is a 20A fuse and feeds HORN and RELAY, provides power for INST lamps, TAIL, LICENSE, SIDE MARKERS, and PARKING

If you do not have good power to that last fuse, you won't have power to the light switch for the tail/ markers/ dash and parking.
So on a 74 Duster the dash and some get power from the switch internally. Leading me to believe since I have side markers and tail ( one anyhow waiting on a socket. Had both but on bright when headlight pulled on. Dim when applying brake. May need turn signal. Can't get one in Tampa) I may need a new headlight switch to have done and dash?
 
done? You mean DOME? The only thing the headlight switch does with dome is ground the common yellow switch wire, same as the door switches do.
 
done? You mean DOME? The only thing the headlight switch does with dome is ground the common yellow switch wire, same as the door switches do.
Ok. I thought they were on the dash circuit. I was mainly trying to figure out my dash lights. Sorry. I value your time and expertise . Thank you
 
Ironracer. I see you posting onto old threads. My advice is to start your own thread.
Take your time typing it out, and edit as needed to make it easier on everyone trying to help.

If you want to reference older threads, hover your mouse over the post number, right click on the post number and select copy.
Then paste that in your post.

For example, this is a link to a post I recently made with description and sketch of the headlight switch wiring.
No power lights etc but ignition turns over?

As far as dimming goes. Lights dim when there isn't enough power available to supply them at the voltage when they were brighter. This might be normal or might be due to resistance in the wiring from the power supply.
Again I encourage you to start your own thread.
 
Ironracer. I see you posting onto old threads. My advice is to start your own thread.
Take your time typing it out, and edit as needed to make it easier on everyone trying to help.

If you want to reference older threads, hover your mouse over the post number, right click on the post number and select copy.
Then paste that in your post.

For example, this is a link to a post I recently made with description and sketch of the headlight switch wiring.
No power lights etc but ignition turns over?

As far as dimming goes. Lights dim when there isn't enough power available to supply them at the voltage when they were brighter. This might be normal or might be due to resistance in the wiring from the power supply.
Again I encourage you to start your own thread.
Ironracer. I see you posting onto old threads. My advice is to start your own thread.
Take your time typing it out, and edit as needed to make it easier on everyone trying to help.

If you want to reference older threads, hover your mouse over the post number, right click on the post number and select copy.
Then paste that in your post.

For example, this is a link to a post I recently made with description and sketch of the headlight switch wiring.
No power lights etc but ignition turns over?

As far as dimming goes. Lights dim when there isn't enough power available to supply them at the voltage when they were brighter. This might be normal or might be due to resistance in the wiring from the power supply.
Again I encourage you to start your own thread.
Yes sir! That link kinda spelled it out to me. When it's not raining and I'm not working I'm going to go out there first chance I can get and check the pink wire at the tail light fuse for power going up to be too cuz I'm definitely not getting it through the switch to the tan wire. Once I verify that, I will start a tread. Thanks again,
Chuck
 
Ironracer this old thread had me confused. You did say, right? That you DO have tail/ park/ side markers? If you do, and you do NOT have dash lamps, then the trouble is either IN THE SWITCH or IN THE inst fuse (the tan goes from the dash dimmer control TO the INST fuse, and then to dash lights

If you do not have it on the tan going into the fuse, then it is a bad dash dimmer control Try twisting the control vigorously from left to right a few times to "clean" the rheostat

You know the trick about pulling the switch? AKA the release button for the knob and shaft?
 
Ironracer this old thread had me confused. You did say, right? That you DO have tail/ park/ side markers? If you do, and you do NOT have dash lamps, then the trouble is either IN THE SWITCH or IN THE inst fuse (the tan goes from the dash dimmer control TO the INST fuse, and then to dash lights

If you do not have it on the tan going into the fuse, then it is a bad dash dimmer control Try twisting the control vigorously from left to right a few times to "clean" the rheostat

You know the trick about pulling the switch? AKA the release button for the knob and shaft?
Yes sir. If its the same as a 66 I've had then out before. Everything works except dash. I will try twisting the knob some more. Maybe contact cleaner. But I'll make sure the power is coming in on b 2from the tail circuit by checking wire. Thank you so much!
 
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