Lighting problem

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Dustin

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Im new to the site and the '72 Duster I bought. Only lights that work are headlights (hi and low beams), both blinkers (also the cluster blinkers work), the oil dummy light, and the highbeam light in the dash. The rest of my cluster lights dont work (put new bulbs and sockets in), all the running lights dont works, and no brake lights. Im missing one reverse bulb, but I wouldn't think that would cause it. Any one got any ideas? I dont know where to start, i'm not much of an electrical wizard. Thanks.

The car is completely original right now except the interior I almost have complete. Its a Gold Duster with a/c, /6, auto, and is a one owner from AZ with 64k miles.
 
Just did alittle testing under the dash, only one fuse has power to it and going through it (c/ltr and dome lp fuse). Also the brake light switch checked out ok.
 
I just pulled the switch out and tried another one I had, samething. So I pulled that switch out and used a jumper wire from the main black wire to the black/yellow tracer on the plug and the exterior running lights lit up. Does this mean I have a bad ground? Do those lights go through the fuse block? Some of the labels on the fuse block are wore off so I cant read every fuse.

Also used the jumper wire to every connector on the plug for the headlight switch. One turned on the headlights one turned on the cluster lights, one turned on the parking/running lights and two didnt do anything that I could see.
 
Something I've REALLY been pushing lately is "do you have a shop manual?"

There's one you can download free right here:

http://www.forabodiesonly.com/mopar/showthread.php?t=132309&highlight=manual,+download

Index to wiring starts on page 8-144.

About 8-151 is the instrument panel wiring

The only lights -that I'm aware of- that are not fused are your headlights. These are "fused" by means of the breaker that is built into the headlight switch.

But most power "from" the fusebox either comes from the "battery" feed (hot all the time, like stoplights)

or it comes from the ignition "accessory" feed--hot only in "run" or "accessory" like the radio, heater

HOWEVER it appears to me that the "instrument" fuse comes directly from the headlight switch, so it may be getting it's power from the main feed to the headlight switch and through the switch mounted breaker

(Notice wire E1-18T) (tan) coming down from the headlight switch TO the instrument fuse. THIS IS THE POWER INTO the fuse

This is a clip from page 8-151

vmujie.jpg


"MyMopar" has simplified wiring diagrams that are completely different from the shop manual, but are sometimes easier to follow:

http://www.mymopar.com/downloads/1972/72ValiantA.JPG

http://www.mymopar.com/downloads/1972/72ValiantB.JPG

Page 8-127 gives you the functions of the fuses:

jsm39g.jpg


And, I REALLY had to look, but here's a photo of your fuse panel from page 8-69

ouw3d1.jpg
 
Thanks that helped a bit. The pictures of the fuse panel (picture 1 and 3 you posted) are missing the brake lamp fuse that is between the instrument lamp fuse and tail/horn fuse. I tested all the fuses again now that I know which ones are keyed and which ones are hot. All the fuses work properly except the brake lamp fuse and instrument cluster fuse have no power going to them. So the fuse for my parking and tail lamps works. That must mean both of my headlight switches are bad or could it be a bad ground? Looks like the cluster fuse gets its power from the headlight switch also which isnt getting power. The brake lamp fuse gets its power from somewhere else, the brake light switch on the pedal? I have power on both sides of the brake switch when the pedal is depressed.
 
Compare the wiring diagram above the photo of the fuse box. The two are reversed left to right

In the photo, the instrument fuse gets power from the headlight switch

the next two fuses get power from "battery feed" and are always hot." The last three on right get power from ign switch in "run" or "accessory."

If your brake light switch is "hot on both sides, with pedal down, it is OK. from there, the brake lights feed IN to the turn signal switch and are separated. So if the brake lights don't work, and you have power at the BL switch, it's either the TS switch, the harness to the rear, or the bulbs or grounds

Look at the chart above the photo, it shows what all is in which fuses The stop/turn/ lamps are all on the cigar lighter fuse.

Tail and park are on the tail fuse, of course

To conclude, it SOUNDS like the brake light switch has power, therefore the switch should be getting power FROM the fuse, which gets power from the "battery" feed---hot all the time
 
This is my fuse block. The 2nd fuse from the top is labeled brake/lp

Also the 4 ways dont work but the turn signals do. I energized the brake fuse and a big rectangle relay was clicking by the glove box (not the little round one for the turn signals). Im probably going to get a new relay and headlight switch. Although both my headlight switches I have only light up the headlights.
 

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The fuse for the dash lights doesn't have power on it until the headlight switch is pulled at least to the park lamp position. All other fuses are either Hot at all times or hot in run. The one fuse stands alone in how it gets its power. Dash lights and brake lights are in no way related.
 
Did a bunch of testing and tracing today. The fuse labeled brake/lp, thats wired in with the ignition system to the steering column and to the ballast resistor, ignition box, and alternator. (ignition 1 in the diagrams)

Everything I tested seemed ok, besides possibly the 4 way flasher switch. Can it cause the brake lights not to work?

Still haven't figured out the running lights and cluster lights.
 
Dustin said:
possibly the 4 way flasher switch. Can it cause the brake lights not to work?.
Click to expand...

Absolutely a problem in the 4 way/ TS switch can cause the brake lights not to work.

You mentioned "a relay clicking in your glove box." It is PROBABLY the 4 way flasher which is separate from the TS flasher
 
67Dart273 said:
Absolutely a problem in the 4 way/ TS switch can cause the brake lights not to work.
Click to expand...

I think that maybe the problem. I just found this posted by Redfish which is the same problem im having but the wires for my rear lights are green and brown instead of green and yellow.

RedFish said:
You should find a off white wire feeding power up the column to the signal switch . If there is no power comming back down on green and yellow wires in same connecter... there's your sign :(
Signal switch is about 60.00 average and it takes half a tool box full of stuff to change it. Good luck
Click to expand...
 
RedFish said:
The fuse for the dash lights doesn't have power on it until the headlight switch is pulled at least to the park lamp position. All other fuses are either Hot at all times or hot in run. The one fuse stands alone in how it gets its power. Dash lights and brake lights are in no way related.
Click to expand...

Now that I think I figured out the brake lights (gotta find and order and flasher switch) im trying to figure out the cluster and running lights. I dont get any power to the instrument panel fuse with the light switch pulled nor do the running lights come on. This is the 3rd headlight switch ive tried. If i unplug the switch and use a jumper wire from the hot plug on the harness for the switch, and jump to the plugs for the running and instrument panel lights they work. Any ideas? The switch shouldnt have to be grounded if I can use a jumper wire to light them up does it?

I dont know if this matters but there is no radio in it, and the heater controls dont seem to work. The buttons are jambed, and the blower motor doesnt turn on (could be cause the buttons are jambed?). Theres a couple plugs where the radio goes that arent plugged into anything. One has 2 female ends one with 2 orange wires, the other has a red and white wire. The other plug has 2 femaly ends one with a green wire, the other has a brown wire.
 
OK, the light switch RECEIVES power from two sources. ONE is a "heavy" unfused feed that runs the headlights, and it goes through a breaker that is built into the switch

Look at the top diagram I posted above, which shows the fuse box and light switch

On the bottom left of the switch, marked "B1" in the diagram, is fed by a black wire. THIS WIRE IS ALWAYS HOT and is not fused, and feeds the headlights.

THE TAIL AND PARK lamps do not get power from this feed. They get power from the terminal marked "B2", fed by wire no L8-18P, and amazingly enough, comes up from the fusebox "tail" fuse.

What you need to do is make SURE that both "B1" and "B2" are hot at the switch.

Looking at the picture of the somewhat rusty fuse clips on your fusebox, I would guess you are losing it right there. You should have power on BOTH SIDES of the fuses fed "hot" and you should have power on both sides of the other fuses (except the instrument fuse) with the key in run.

IN OTHER WORDS with the key in run, ONLY the instrument fuse will be dead (with light switch off) ALL OTHER FUSES should have power on both sides of them.
 
Thanks for bearing with me on this. Just went out and checked, all fuses have 12.7v on bothsides the except instrument cluster, and that random one thats labeled brake. Also have 12.7v at B1 and B2 but no running lights or dash lights. This is the second new switch ive tried in it.
 
Best I remember is that the turn signal flasher unit is mounted on a bracket connected to the side of the ash tray. The four-way flasher is mounted on a clip on the left side of the steering column brace way up under the dash. These flashers are cylindrical, about 1" in diameter. I've seen silver metal and light blue plastic cases on them. Hope this helps.
 
That push button climate controller has a lamp on it. The radio dial had a lamp in it. All of these scattered lamps all get the same feed from the headlight switch. All on orange wires. Any one of them can blow that fuse instantly.
We can go back to the jammed push buttons later. It's a common failure. You'll need a new switch there. Hope this helps
 
Got running lights and cluster lights! Hopefully a 4 way and blinker switch from my buddies '72 Scamp parts car will make my brake lights light up! Going to try that tomorrow night if it doesn't get to late. You guys are a huge help!
 
A new hazard flasher might be a better plan. 40+ year old electrical parts are... well you already have one of those :)
Happy moparing
 
Where can I get one for a '72? When I was searching around here, I seen one for a '73 but it had an extra plug with 2 wires. Mine is just a single plug with I believe 8 wires if I remember correctly.
 
With the brake light problem. I have 12.6 volts to the hot side brake light switch, 12.6v on both sides of the switch when the pedal is depressed, and 12.4v at the plug on the white wire at the steering column (the brake light wire feed). If I plug in either of the 2 used blinker/4 way switches I have 12.6 volts on the hot side of the brake light switch. Then when I depress the brake pedal, im down to 11.4v on the hot side of the brake light switch, and 0 volts on the other side of the switch which leads to 0v at the plug for the blinker/4 way switch. Any idea of what is going on here?
 
We need wire colors you are seeing, and look if this matches what you have

The wires, top to bottom in this diagram are just what they say

18W (white) STOP LAMP should be power coming into the switch from your stoplight switch

18BR (brown) power going OUT of the switch to right rear stop/ turn

18GN (dark green) power out to left rear stop/ turn

18R (red) power coming INTO switch from signal flasher

18P (purple) power coming INTO switch from hazard flasher

Make sure the switch is centered, make sure the hazard switch is off, and you should get continuity from the top (white) to both brown and dark green

It is VERY common for the hazard section of the switch to fail and cause the brake lights not to work, but leave the signal flashers functional





30j6y9y.jpg
 
That matches what I have. I just wanted to make sure the brake lights worked so I used jumper wires and another battery to the brown and dark green wires. The brake lights light up. The 18w wire is the one ive been testing. Ill have to test the hazard switch wires for continuity once and see what I get. The hazard switch would cause the 18W wire from the brake light switch to go dead when plugged in and the pedal depressed?
 
Dustin said:
The hazard switch would cause the 18W wire from the brake light switch to go dead when plugged in and the pedal depressed?
Click to expand...

No, but it will block the power from the white wire going through the switch to the brake lights, and this used to be a failure point.

I can remember a couple of "poor" sailers both had B body cars with a column mounted hazard switch, and the TS switch went bad--no brake lights.

I used to be able to cut the hazard knob off (disable the switch) and make a wiring change to get around the problem.

That's been a LOOOOONNNGGG time ago, don't remember anymore how I did that

So what I'm saying is two things:

Having the turn signal switch off center will disable one brake light

Having a failed signal switch can cause loss of both brake lamps but still allow the signals to work.
 
'A long time ago someone posted that if the hazard lights were on in a early A and you stepped on the brake pedal the radio would play.
I know the hazard lights override turn signals and I know current can travel backward in a circuit which would explain the radio thing.
I dont know if this is relative to your problem but the hazard circuit may be interrupting/disconnecting the brake lights by design.
 
Just put in a brand new blinker/4 way switch, still no brake lights. I have power to the brake light switch. When the blinker/4 way switch is plugged in (the plug shown above), I can not get power to go through the brake light switch when the pedal is depressed. If I unplug the blinker/4 way switch at the plug I get power through the brake light switch to the white wire of the chassis side of the blinker/4 way plug. Im lost to why this is.
 
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