Dash Lighting issues...

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Ellis_Galleher

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1964 plymouth valiant, v8 318
For the past few days, I have been trying to figure out why my dash lights won't come on. Just got all new bulb sockets, all new bulbs, and a new circuit board as well as a new headlight switch. There is a 2 amp fuse in the correct spot of the fuse block. Testing the orange connector that goes into the back of the dash, there is 12v coming out. With the headlight switch half pulled and the car in ACC mode, the light to indicate that the switch has been pulled is super bright, however, the lights behind the gauges barely light. Then once I pull the headlight switch all the way out, they just completely shut off. Any ideas what it could be. Dimmer switch is all the way to the left in the pictures as well. Pictures are attached.


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You may have a cluster grounding issue

I don't know what you mean by:

"With the headlight switch half pulled and the car in ACC mode, the light to indicate that the switch has been pulled is super bright"

Here is how dash lights work. They are a bit of a trick

First, ONLY the headlights are supplied power separately to the light switch, terminal B1 on the switch

A second terminal, fed by the tail circuit fuse, feeds power to the B2 terminal of the switch. This powers park/ tail and dash lights

That power, with the switch either in park or head, goes through the dimmer, which as you mentioned, must be turned to the left. But turn and twist and wiggle it because they can become dirty and intermittet

That power, then out of the dimmer control, goes out of the headlight switch on tan, and down TO the 2A INST fuse. From that fuse, the dimmer controlled dash light power goes out on ORANGE wires to all the various dimmer controlled lamps. Cluster, radio, shift quadrant, whatever.

The orange wire you checked ??? may be a wrong wire. With the dimmer variable, and some load on the dash light circuit, that line should be BELOW 12V and should vary as the dimmer is turned.
 
67Dart273 said:
You may have a cluster grounding issue

I don't know what you mean by:

"With the headlight switch half pulled and the car in ACC mode, the light to indicate that the switch has been pulled is super bright"

Here is how dash lights work. They are a bit of a trick

First, ONLY the headlights are supplied power separately to the light switch, terminal B1 on the switch

A second terminal, fed by the tail circuit fuse, feeds power to the B2 terminal of the switch. This powers park/ tail and dash lights

That power, with the switch either in park or head, goes through the dimmer, which as you mentioned, must be turned to the left. But turn and twist and wiggle it because they can become dirty and intermittet

That power, then out of the dimmer control, goes out of the headlight switch on tan, and down TO the 2A INST fuse. From that fuse, the dimmer controlled dash light power goes out on ORANGE wires to all the various dimmer controlled lamps. Cluster, radio, shift quadrant, whatever.

The orange wire you checked ??? may be a wrong wire. With the dimmer variable, and some load on the dash light circuit, that line should be BELOW 12V and should vary as the dimmer is turned.
Click to expand...
So on my headlight switch, I can pull it half out... not too sure what it does, but headlights do not come on but the dash lights do as shown in the picture. Once I pull the headlight switch all the way out, the headlights and tail lights come on but the dash lights turn off as shown in the 4th picture. I got a new dash harness when I first got the car so the orange wire im checking is part of that cluster of wires that plugs into the back of the circuit board.

64ValiantA_edit.jpg
 
Ground the dash to the body. 5 bucks says the dash lights will work correctly.
 
The clusters are only grounded through the mounting bolts. It is a wise idea to add a pigtail to a grounding point on the cluster long enough to access, and bolt it to the dash frame,/ column support
 
67Dart273 said:
The clusters are only grounded through the mounting bolts. It is a wise idea to add a pigtail to a grounding point on the cluster long enough to access, and bolt it to the dash frame,/ column support
Click to expand...
In the photos he has the cluster out of the dash when he is testing, my bet is he does not have a ground and is back feeding all kinds of circuits to light the dash lamps, hence the odd headlight switch behavior.

He is also probably back feeding to make the gauges function which could have disastrous effect on the gauges if the ground path is lost.
 
Did you get the right bulb sockets? The really common ones are 1/2. I think the Mopars all use 5/8 in those years.
 
All good suggestions and yes the wrong sockets will add to the frustration. I went through this with my ralley dash, it was a combination of wire repairs and I did run a ground also like said. The wiring diagram ,study it, know it it helps.
 
67Dart273 said:
The clusters are only grounded through the mounting bolts. It is a wise idea to add a pigtail to a grounding point on the cluster long enough to access, and bolt it to the dash frame,/ column support
Click to expand...
Dana67Dart said:
In the photos he has the cluster out of the dash when he is testing, my bet is he does not have a ground and is back feeding all kinds of circuits to light the dash lamps, hence the odd headlight switch behavior.

He is also probably back feeding to make the gauges function which could have disastrous effect on the gauges if the ground path is lost.
Click to expand...
So if I just put the screws back in and mount it, it should work correctly? But I should also add a ground strap for better ground?
 
yes try the strap, but you may have to trace power and ground through the whole dash including the circuit boards. This is where you may need the wiring diagram.
 
Ellis_Galleher said:
So if I just put the screws back in and mount it, it should work correctly? But I should also add a ground strap for better ground
Click to expand...
You can just get a jumper with alligator clips on each end for testing.

Without a ground you can supply 12 V to your gauges and burn them out.

As for additional grounding it can't hurt
 
So I added an external ground and mounted it to the body.. .everything works now. Lights come one, and the dimmer works as well!!!
Thank you all for helping with the issue.
 
It's the simple things!

These videos are corny but very informative.

 
Ellis_Galleher said:
So if I just put the screws back in and mount it, it should work correctly? But I should also add a ground strap for better ground?
Click to expand...
It should. I always add a ground wire for good measure.
 
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