Dash light issues

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RonsSwinger

RonsSwinger

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Looking for some assistance with dash lights. I bought the car (71Dart) a year or so ago and the dash lights didn’t work. It would blow fuses as soon as I changed them. I replaced the headlight switch and corrected it. It lasted a couple of months (driving periodically) and the dash lights are gone again, and instantly blowing fuses. Any thought, if someone suspects a short of some kind is there way to troubleshoot the issue. If the issue took out my headlight switch again, any ideas why?Thanks in advance Ron D
 
The dash lights are fed from a rheostat in the headlight switch.

I suspect you have a short somewhere in the dash light/radio light/gear selector light circuit.

The rheostat can take a short for some time till it melts and opens making the circuit dead.

Go get a wiring diagram from mymopar.com if they do t have your year look for the closest year.

And trace out the wires.

Disconnect all dash/radio/gear selector lights and see if the problem still exists. A test light might be helpfully.
 
The dash illumination lamps are a trick and are the only ones wired this way.

The power for them comes from the tail/ park circuit fuse, TO the light switch, and then the light switch powers the dash lamp dimmer control. THEN the power LEAVES the light switch on the tan wire and goes TO the little INST fuse at one end of the fuse panel. From there, dimmer controlled lighting power is distributed on ORANGE wiring, to the cluster, ash tray, radio, where ever is a dimmer controlled lamp If you look into the back of the fuse panel you will see one terminal with a bunch of orange wires.

That might be tough to run down

Does it have an aftermarket radio? Maybe someone did a crap job of splicing. Do you have a column auto shifter? Maybe movement inside the column damaged that wire, to the shift quadrant indicator. I would for sure check the ash tray.

Do you / did you have a center console? It may have had a lighted shift quadrant etc, and the harness going to it, under the carpet might have been damaged.

If that kind of looking you don't find it, at the worst you could carefully clip the orange wires, perhaps one at a time and test them.

To avoid blowing fuses and to avoid damaging another light switch, get yourself a tail/ stop lamp and socket and wire in series from the battery to the test device. You can use that to jumper power to each cut wire. The shorted one will light the stop lamp brightly, but will not damage the wiring. Then solder/ otherwise splice them back into place.
 
My first thought is what did somebody add to that circuit some time in the last 50 years...
 
str12-340 said:
My first thought is what did somebody add to that circuit some time in the last 50 years
Click to expand...
That's a possibility...

Since lights work for a short time after the light switch replacement.

Maybe someone added a device to the dimmer light cir that is drawing too much current.
 
I would consider removing the cluster so I could inspect and test it on the bench.
 
Murray said:
I would consider removing the cluster so I could inspect and test it on the bench.
Click to expand...
Haha, I saw what it takes to remove the cluster. I think you have to drop the steering column and remove the dash. That is far past my skill set. I will be hoping for a smaller issue. This is the last case scenario.
 
67Dart273 said:
The dash illumination lamps are a trick and are the only ones wired this way.

The power for them comes from the tail/ park circuit fuse, TO the light switch, and then the light switch powers the dash lamp dimmer control. THEN the power LEAVES the light switch on the tan wire and goes TO the little INST fuse at one end of the fuse panel. From there, dimmer controlled lighting power is distributed on ORANGE wiring, to the cluster, ash tray, radio, where ever is a dimmer controlled lamp If you look into the back of the fuse panel you will see one terminal with a bunch of orange wires.

That might be tough to run down

Does it have an aftermarket radio? Maybe someone did a crap job of splicing. Do you have a column auto shifter? Maybe movement inside the column damaged that wire, to the shift quadrant indicator. I would for sure check the ash tray.

Do you / did you have a center console? It may have had a lighted shift quadrant etc, and the harness going to it, under the carpet might have been damaged.

If that kind of looking you don't find it, at the worst you could carefully clip the orange wires, perhaps one at a time and test them.

To avoid blowing fuses and to avoid damaging another light switch, get yourself a tail/ stop lamp and socket and wire in series from the battery to the test device. You can use that to jumper power to each cut wire. The shorted one will light the stop lamp brightly, but will not damage the wiring. Then solder/ otherwise splice them back into place.
Click to expand...
That is more than I read in highschool…… thanks for the extensive details. No radio (radio was removed). The car is a 440 conversion with a B&M floor shifter. The fuse that blows is the bottom of the fuse panel (going by memory). On a good note I still have park lights (just losing dash lights and tach light). This gives me a great starting point.
 
All of the the instrument lights including a factory tach use the same fuse.
1702126632896.png


The parking light fuse is often shared with other circuits, but since its the instrument fuse (probbaly 3 amp in '71) then its downstream of the fuse.
If the bulbs are not burned out then I would follow the orange wires looking for locations any one of them could rub or chafe against sheet metal.

The diagram in the '71 shop manual may show the junctions for the the instrument lamp feed (orange wire).
I've found on my 67 the orange wire goes from the fuse box to the steering column connector where it is spliced to another orange wire. That second wire then has a welded junction in it buried in the harness. One wire goes to the console, another to one side of the instrument cluster, and the last to the other side of the instrument cluster. If you see two orange wires at the column connector, that's an easy place to disconnect and test for shorts to ground. That's just an example of how to narrow down the problem location.
 
Pull the cluster and check all the wiring to make sure it hasn't rubbed through the tape and insulation and is grounding to the dash frame...

I had that happen once on a 69 valiant...
 
1702127733501.png


The 71 FSM shows two wires from the instrument fuse. You'll have to look at the manual to see the next junction - assuming actual production matches the diagram.
 
Mattax said:
All of the the instrument lights including a factory tach use the same fuse.
View attachment 1716176283

The parking light fuse is often shared with other circuits, but since its the instrument fuse (probbaly 3 amp in '71) then its downstream of the fuse.
If the bulbs are not burned out then I would follow the orange wires looking for locations any one of them could rub or chafe against sheet metal.

The diagram in the '71 shop manual may show the junctions for the the instrument lamp feed (orange wire).
I've found on my 67 the orange wire goes from the fuse box to the steering column connector where it is spliced to another orange wire. That second wire then has a welded junction in it buried in the harness. One wire goes to the console, another to one side of the instrument cluster, and the last to the other side of the instrument cluster. If you see two orange wires at the column connector, that's an easy place to disconnect and test for shorts to ground. That's just an example of how to narrow down the problem location.
Click to expand...
BAMM. I love pictures. This info will narrow down the hunt. Thanks RonD
 
Pulling the cluster is not as hard as it sounds. If you don't have a service manual, go over to MyMopar.com and download one, free

The basics of pulling the cluster
(I am 75, and have done this in the last couple of years)

1..Disconnect battery ground
2...If able reach up into dash from underneath and release the clip to release the speedo cable
3...Remove couple of screws under column, and remove small trim piece under column
4...Locate and remove column retention nuts which are normally studs from the top Leave 1 each side installed loose
5...Pull up carpet near column and pull bolts through floor flange/ column clamp into floor.
6...If possible go into engine bay and punch the roll pin out of steering coupler at box, and pry coupler off steering box. You may NOT need to do this

Alternatively, the coupler will "hinge" better in two directions 1/2 turn apart, because of the way it operates. Unlocking the column, and rotating the wheel, will optimize that position if the coupler cannot be disconnected.

7...Pull the column electrical connectors to the ignition switch and the turn signals

8...Remove the nuts you left loose to hold the column and let it rest in the seat. Again, you may want to turn the wheel to allow this You may also want to disconnect the shift linkage. This "pops" out of a plastic'y grommet with a knob on the end of the link.

Now remove the screws around the cluster edge

9.. Sort of "hinge" the cluster easily out and tip it downwards, until you can reach in and disconnect the two nuts on the ammeter. Pull loose the harness connector off the PC board, and look for the harness hanging up or retention, and pull off the speedo cable if not already done.

10...Carefully work the cluster out

To work on the car with battery connected, now bolt the two (big black and big red with eyelets) ammeter wires together. The black IS NOT ground. Tape it up temporarily for safety.

11...RE--connect the turn signal and igntiion switch and now you can run the car if necessary, and everything except the cluster should work.
 
67Dart273 said:
Pulling the cluster is not as hard as it sounds. If you don't have a service manual, go over to MyMopar.com and download one, free

The basics of pulling the cluster
(I am 75, and have done this in the last couple of years)

1..Disconnect battery ground
2...If able reach up into dash from underneath and release the clip to release the speedo cable
3...Remove couple of screws under column, and remove small trim piece under column
4...Locate and remove column retention nuts which are normally studs from the top Leave 1 each side installed loose
5...Pull up carpet near column and pull bolts through floor flange/ column clamp into floor.
6...If possible go into engine bay and punch the roll pin out of steering coupler at box, and pry coupler off steering box. You may NOT need to do this

Alternatively, the coupler will "hinge" better in two directions 1/2 turn apart, because of the way it operates. Unlocking the column, and rotating the wheel, will optimize that position if the coupler cannot be disconnected.

7...Pull the column electrical connectors to the ignition switch and the turn signals

8...Remove the nuts you left loose to hold the column and let it rest in the seat. Again, you may want to turn the wheel to allow this You may also want to disconnect the shift linkage. This "pops" out of a plastic'y grommet with a knob on the end of the link.

Now remove the screws around the cluster edge

9.. Sort of "hinge" the cluster easily out and tip it downwards, until you can reach in and disconnect the two nuts on the ammeter. Pull loose the harness connector off the PC board, and look for the harness hanging up or retention, and pull off the speedo cable if not already done.

10...Carefully work the cluster out

To work on the car with battery connected, now bolt the two (big black and big red with eyelets) ammeter wires together. The black IS NOT ground. Tape it up temporarily for safety.

11...RE--connect the turn signal and igntiion switch and now you can run the car if necessary, and everything except the cluster should work.
Click to expand...
Thanks for the detailed step by step. If I can’t find a simple solution I will use this as a guideline to remove the dash board.
 
I forgot to mention, if ANYTHING which is lighted has been added, such as tach or accessory gauge panel, check that FIRST
 
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