how to bench test a 70 Dart instrument cluster?

Here is the back side of the passanger side cluster cir board as seen from the front of the car.

1. Yellow X is oil pressure light
2. Green Xs are instrument panel lighting
3. Fuchsia X is the right turn signal indicator light
4. Blue X is the high beam indicator light.
5. Red Xs are where the Amp meter passed through the cir board. (It is completely insulated from the cir board)
6. White dots are cir board ground points
7. 2 red dots are the input and output for the oil indicator lamp. yellow
8. Yellow dot is 12 volt input for instrument panel illumination
9. Green dot is 12 volt input for the right turn signal indicator
10. Blue dot is 12 volt input for the right turn signal indicator

The following assumes the cir boards are still attached to your cluster

To test any all of the light bulbs EXCEPT the Oil light Indicator do the following:

1. Get a 12V power source (car battery, 12V DC power supply, 12V lantern battery)
2. Get or make some wires with alligator clips on both ends
3. Connect the negative of the power source to the metal of the cluster, there is a spring metal clip on the back of the cluster by the speed cable connection that would do fine
4. Connect the positive side of the power source to pin with the blue dot, the high beam light bulb should light up
5. Connect the positive side of the power source to pin with the green dot, the right turn signal indicator light bulb should light up
6. Connect the positive side of the power source to pin with the yellow dot, the instrument panel light bulbs should light up

To test the Oil indicator light

1. Remove the negative of the power source from the metal of the cluster
2. Attach the negative of the power source to one of the pins with the red dot
3. Attach the Positive of the power source to the other pin with the red dot, the oil light should light up

For now we are going to leave the ammeter alone. (By the way, the posts on the ammeter, if rotated, WILL short the ammeter to ground causing an electrical melt down of the wiring in your car)

The Gauge posts are also sensitive to rotation. I damaged an otherwise good gauge by un-screwing the nut on the back. the nut was corroded enough that the post spun runinig the gauge. after that I use two gam nuts on the post before starting to loosen the nuts. then take off the jam nuts than remove the gauge nut





Here is the back side of the Drivers side cluster cir board as seen from the front of the car.

1. Yellow X is Fuel Gauge Sender input
2. Blue X is the Temp Gauge Sender input
3. Red and yellow Xs are the approximately 5V output from the IVR and the input to the two gauges
4. Red X is the 12V feed to the IVR
5. White X and Dots are ground points
6. Green Xs are the instrument panel illumination bulbs
7. Fuchsia X is the drivers side turn signal indicator bulb
8. Green dot is the instrument panel illumination bulbs 12V input pin
9. Fuchsia dot is the drivers side turn signal indicator bulb 12V input pin
10. Red dot is the IVR 12V input pin
11. Yellow dot is input from the Fuel Sender to the Fuel gauge
12. Blue dot is the input from the temperature sender to the temp gauge

The following assumes the cir boards are still attached to your cluster

To test any all of the light bulbs do the following:

1. Get a 12V power source (car battery, 12V DC power supply, 12V lantern battery)
2. Get or make some wires with alligator clips on both ends
3. Connect the negative of the power source to the metal of the cluster, there is a spring metal clip on the back of the cluster by the speed cable connection that would do fine
4. Connect the positive side of the power source to pin with the fuchsia dot, the drivers side turn signal indicator light bulb should light up
5. Connect the positive side of the power source to pin with the green dot, the instrument panel light bulbs should light up

To test the gauges ( more complicated) do the following:

1. Get a 12V power source (car battery, 12V DC power supply, 12V lantern battery)
2. Get or make some wires with alligator clips on both ends
3. Connect the negative of the power source to the metal of the cluster, there is a spring metal clip on the back of the cluster by the speed cable connection that would do fine
4. connect the positive side of your power source to the pin with the red dot
5. With your multimeter check voltage from ground to the red and yellow Xs, you should see a fluctuating voltage (it should not read 12V) it will typically read 3V,7V,5V,6V it will be all over the place (there is anther way to check this but for now this will do) the nominal voltage is 5-6V
6. Here is where it gets complicated...
7. You will need a resister or 3, as 67Dart273 showed, the low, half and high gauge readings need the following resistance values to make the gauges needles move. approximately 10, 23 and 74 ohms. (NOTE: The resisters should be a minimum of 1 watt) The actual values are not too important as long as they are close like 10 25 and 75 would work. You could get 1x 50 Ohm, 2X 10 ohm and 1x 5 ohm and make close enough to the needed resistance values
8. With the power source hooked up as in step 1, 2, 3, 4 connect one end of a resister to a jumper wire and connect the other end of the jumper wire to the metal of the cluster. The same place you hooked the negative battery in step 3 is perfect.
9. With another jumper wire connect the other end of the resister to the yellow pin OR the yellow X (NOTE when attaching to the ins be sure not to touch the pins next to the pin you are testing)
10. This will test your fuel gauge. If you used the 10 Ohm resister the gauge should read Full or very close to or just over Full
11. With the 23 Ohm resister the gauge should read about half
12. With the 74 Ohm it should read empty
13. To test the Temp gauge follow steps 1 thru 9 BUT attach to the yellow X or the pin with the yellow dot

There are multiple failure points along the way like pins on the cir board that are not making connections or the nuts on the gauges with bad connections, bad IVR, bad gauges.


so do your testing and report back.


AS THE VIDEO SAYS.... If you short the gauge sender inputs you will fry the gauges. if you had an older style mechinical IVR and you did not ground the cluster you will fry the gauges (thats why My dart is up on blocks right now.)