none of my gauges are working.

[kenicb]

71 dart

temp gauge, fuel gauge, and Ammeter have stopped working.
as per the 71 service manual, I tested the voltage limiter with a test lamp on the back prongs of the gauges. The test light pulsed as it should. So voltage limiter is working.

The other option in the service manual is vague and says to check for faulty wiring or a bad ground from the battery. Can you help me understand what to check next please?

I went to the alternator. it has 3 terminals. one of the field terminals (green wire to the voltage regulator) is loose and won't tighten up. Will this affect the gauges?

all light bulbs and turn signals are working. the 3 gauges do nothing.

thanks so much. God Bless

Keni

 

[67Dart273]

You undoubtedly have TWO separate problems, as the ammeter is not interconnected with the temp/ fuel gauge.

First thing to try is the "quick and dirty" check.

Pull loose the temp sender wire, because it's easy to reach, and clip it to ground. Watching the gauge, turn the key to "run" and watch. The gauge should QUICKLY head for "hot." Don't leave the key on any longer than to tell if the gauge is moving well towards the high mark.

Here, generally, is how the gauge troubles break down. The instrument cluster receives power from what is called "IGN 1" or "ignition run", traditionally DARK BLUE. This branches off from the ignition switch, and feeds the cluster, and goes out through the bulkhead to feed the ignition, regulator, alternator field (blue) and a few other things, depending.

IF THE warning lamp for the oil / brake (parking brake) works, the cluster is probably getting power.

The general circuit path is IGN switch, -- cluster -- instrument regulator -- (branch off) to both gauges,

through the temp gauge, out through the bulkhead, to the temp sender, to ground

through the fuel gauge, down past the kick panel connector, to the rear through the rear harness, to the fuel sender, to ground

The areas of concern:

IS the cluster actually getting GOOD 12V power?

The cluster connector may be loose/ corroded

The pin(s) on the cluster PC board may be loose / corroded

The brass spring fingers which the instrument regulator plugs into may not be making good contact with the PC board

The nuts on the gauges may not be making contact between the gauge studs and the PC board.

There might be a break in the wire to the sender, especially through the bulkhead to the temp sender.

Just because the vr is pulsing, does not mean it is providing enough power. It may be barely making contact (dirty, worn out) and "under load) may be failing

 

[kenicb]

thank you for taking time to help me with a thorough explanation. Here's what I know


IS the cluster actually getting GOOD 12V power? Yes All lights on the PC are working since I replaced all the bulbs.

The cluster connector may be loose/ corroded
I pulled it cleaned it and pushed it back on

The pin(s) on the cluster PC board may be loose / corroded
they felt solid

The brass spring fingers which the instrument regulator plugs into may not be making good contact with the PC board

Don't know what the brass spring fingers are or where to find them??

The nuts on the gauges may not be making contact between the gauge studs and the PC board.
making good contact

There might be a break in the wire to the sender, especially through the bulkhead to the temp sender.

will start tracing. When I grounded the temp sender the temp gauge started moving.

Just because the vr is pulsing, does not mean it is providing enough power. It may be barely making contact (dirty, worn out) and "under load) may be failing


tried two and get the same results.

 

[67Dart273]

The brass fingers I'm talking about are the contacts that you plug the VR into. Take an ohmeter and look at the pc board. You can easily see the copper leading off from the socket contacts

You have three circuit paths-----

One is ground, and by the way, the cluster MUST be grounded. I recommend you loosen/ tighten all mounting screws on the pc board, find a ground point, and put a "pigtail wire" on one, run it out behind and ground it to the column support behind the panel.

Put your meter on One brass finger contact, and trace where it goes, and check the "other end"

So one contact will lead to ground

One contact will lead to 12V coming into the pins

One contact goes to one stud on each gauge.

You cannot just LOOK at the pins and decide they are tight, use a meter and check them.