Question about gauge cluster circuit boards

[DrillNFill]

Hi everyone! I could use some advice. I have a 1970 Dart Swinger Slant-6 with the standard gauge cluster. It has worked pretty normally for me the past 5 years that I've owned it until this past fall, when I had an upholstery shop replace seat covers and dash pad. Since the day he changed the dash pad, the two left gauges for Temp and Fuel are completely dead and dont work at all. They worked fine previously, like in the photo below from last year. Speedo, alternator and Oil light work normally. I assume the upholstery guy messed up something when he was fiddling under the dash pad.
My old-school mechanic already replaced the cluster voltage regulator and the Temp and Fuel gauges are still dead. He recommended replacing the circuit board as the next step. I already purchased the one pictured below which I believe is the correct one for a 1970 Dart with standard gauges.
Assuming that they stopped working because of the dash pad replacement, and the rest of the car is fine, could there be any other cause of the non-working gauges besides the circuit board? I just want to know if there are any other parts or issues I should be looking into at the same time that could cause this problem. Appreciate any and all advice from you guys!

 

[Oldmanmopar]

Bad voltage limiter or not installed.

 

[Kern Dog]

I just went through this. A helpful member suggested to unscrew the thin sheet metal retainer nuts, clean the circuit board contacts and then retighten the nuts. I did that along with the other screws and then it worked fine.
It could be that the 5 pin wire plug isn't seated all the way:

 

[DrillNFill]

Bad voltage limiter or not installed.

View attachment 1716411619
View attachment 1716411611

The first thing we did was to change out the voltage regulator with an OE-style replacement, they are still dead. I have bought one of those newer-style ones that is supposed to work better, havent tried it yet.

 

[DrillNFill]

I just went through this. A helpful member suggested to unscrew the thin sheet metal retainer nuts, clean the circuit board contacts and then retighten the nuts. I did that along with the other screws and then it worked fine.
It could be that the 5 pin wire plug isn't seated all the way:

View attachment 1716411627

I wonder if the 5-pin plug is the culprit, that seems like something that can loosen up/ be disconnected white installing the dash pad. Thanks!

 

[remytherat]

Check to see if the 5 pin connector on that side is fully plugged in and that the pins are intact. Also cleaning the ground contacts on that side is a good idea.

Replacing the board sounds like a waste of money. Unless the traces are severely damaged, nothing isn’t fixable. Also, if you can’t see anything wrong with it, replacing won’t fix anything.

 

[Oldmanmopar]

Just had a loose pin on a rally dash and the left blinker would not work. Soldered the pin on the face.

 

[RogerRamRod]

I cleaned all my pin to circuit board locations and touched them with a bit of solder when I had my junk apart. Dash pad installer guy bay have just touched something enough with his arm to move a connector a little.

 

[67Dart273]

you really should get the cluster out and do an "end to end" test. There are several things, and yes, the upholstry guy could have wiggled a harness enough to break, say, one of the harness pins.

Generally............

Check carefully ALL the connector pins. They are sort of swaged/ riveted. Clean them, get some electronic compatible solder and flux and solder them

The contact fingers where the IVR plugs in lose contact with the board. Clean, flux, and solder a jumper across from the contact fingers to the board traces.

Loosen/ tighten the gauge nuts several times to scrub them clean.

"Rig" the board to ground and the proper harness pin, and quickly ground the sender pins one at a tme to see if the gauges deflect. Do not do so any longer than necessary. Better is to obtain resistors to simulate the senders and test by hooking a resistor from the sener terminal to ground. Both gauges deflect the same. Now would be a great time to check the ammeter studs for tight, and to clean up the lamp sockets and the board where they make contact.

If you do not have a service manual, wander over to MyMopar.com and download one, for free. You may have to settle for Dodge/ vs Plymouth.

If you replace the IVR I would not get a OEM like replacement, rather, get one from RTE. They are expensive, but way better.

RTE limiter - rte

www.rt-eng.com

Gauge/ resistance test values

 

[DrillNFill]

Thanks for the replies everyone! I feel it’s just too much of a coincidence with having the upholsterer working on it and that day my gauges don’t work. That’s why I figured it’s not dirty contacts or something. I will make sure that the circuit board is properly grounded and all the pins/ voltage regulator are intact and plugged in properly. If it helps narrow it down both turn signals and the cluster lights all work normal- literally it’s just the fuel and temp gauges that are totally dead all of a sudden. The circuit board replacement was not too expensive and I did buy an additional RTE voltage regulator to try also. I just wanted to make sure there wasn’t a third possible culprit I’m overlooking that I may need to order. Thanks again and please I appreciate any more comments/ suggestions!

 

[DrillNFill]

Hi everyone. I finally got this issue sorted out. Like i said in the OP, ever since the upholsterer replaced the dash pad in my 1970 Dart, the temp and fuel gauges stopped working completely. well finally got the gauge cluster out with help from my long-time mechanic, and low and behold a blown circuit on the board. Replaced with new circuit board, everything works perfect again. Thank you to everyone who gave me guidance!