Instrument cluster not working

[Doorjam13]

In my 1972 f100 none of the gauges(speedo works.... bouncing but works) or lights (turn signals work..... weak but work) work. I have pulled the cluster out cleaned the contacts and replaced the IPVR. I'm not sure what else to check.

[colnago]

The speedo/odo are completely mechanical. For the lights, check the ground. That's my bet, if all the gauges and lights are iffy. Use a multimeter, and check the voltage on any of these when powered.

Joseph

[Doorjam13]

The speedo/odo are completely mechanical. For the lights, check the ground. That's my bet, if all the gauges and lights are iffy.

Joseph

This is a dumb question but.... where is the ground for the cluster?

[colnago]

Dumb answer: I don't remember! It's been forever since I've been behind the instrument cluster. Your best bet is to go to the tech area of the forum, and chase down the wiring schematic for your truck. I need to do that, myself, and figure out why my reverse lights don't work.

Joseph

[Russell J]

Is your cluster gauges or idiot lights?

[Doorjam13]

Is your cluster gauges or idiot lights?

Nothing works.... no back lights, no idiot lights and no gauges (only speedo)

[Russell J]

There are two types of instrument clusters. One of them is all gauges. The other type, referred to as "idiot lights", have gauges except for two which
have lights for the oil and alternator. Depending on which type of cluster you have, the plug into the back of the instrument cluster is different. Knowing which type you have will help us point you in the direction of where the actual ground connection is.

[71Fe2O3]

If I remember correctly, instrument panel bulbs are grounded through the circuits that they are part of, so turn signal indicators are part of that circuit, and I believe gauge indicator bulbs are in the marker light circuit; check the wiring diagram to verify.
What about other lights? The turn signal switch is in most if not all light circuits except headlights, so strange things happen when it goes bad. Trouble with several light circuits makes me suspect the turn signal switch. They are available from Dennis Carpenter and other sources. I bought mine from Carpenter and it has worked well for the past year. Installation has been described here.

[Doorjam13]

There are two types of instrument clusters. One of them is all gauges. The other type, referred to as "idiot lights", have gauges except for two which
have lights for the oil and alternator. Depending on which type of cluster you have, the plug into the back of the instrument cluster is different. Knowing which type you have will help us point you in the direction of where the actual ground connection is.

I have all 4 gauges.... fuel, water temp, alternator and oil pressure.

[Doorjam13]

If I remember correctly, instrument panel bulbs are grounded through the circuits that they are part of, so turn signal indicators are part of that circuit, and I believe gauge indicator bulbs are in the marker light circuit; check the wiring diagram to verify.
What about other lights? The turn signal switch is in most if not all light circuits except headlights, so strange things happen when it goes bad. Trouble with several light circuits makes me suspect the turn signal switch. They are available from Dennis Carpenter and other sources. I bought mine from Carpenter and it has worked well for the past year. Installation has been described here.

The turn signals work but they are very weak and slow. I replaced the flasher unit and as for the other lights (head lights etc.) They work fine. The turn signals indicators in the dash work.

[71Fe2O3]

Weak, slow turn signals suggest a bulb or ground problem. Perhaps there is an incorrect bulb, a corroded or damaged socket or fault to ground that causes the circuit to draw too much current. Also, check the wiring for hacks done by previous owners-poor splices, abraded insulation and incorrect connections can cause much electrical mayhem.

Light problems as you describe can also come from the turn signal switch, so you might be well served to probe it with a test light as you activate the various circuits that pass through it.

You might also consider probing the connecter that supplies electricity to the cluster. You should be able to unplug the connector and speedometer, remove the cluster, turn on the light switch and probe the cab side of the connector. Check the wiring diagram to see which wire serves the backlights and gauge lights. That should tell you whether the problem is in the headlight switch or the cluster.

[Doorjam13]

Sooo the latest with my dash checked the ground for the gauges and the ground off the battery..... good. Checked the blinker connectors and one needed to be cleaned up.
I used a test light on the back of the instrument cluster I have power at the connector from the wiring harness, has power.
Check the back of the gauges and they have power.

I'm at a loss, my gauges(not including speedo) don't work and still no back lights in the dash, Heads lights and blinkers work(the blinker indicators in dash work) I'm going to need to run some universal gauges so I make sure the truck doesn't over heat or lose oil presser.

[basketcase0302]

"Doorjam13"]Sooo the latest with my dash checked the ground for the gauges and the ground off the battery..... good. Checked the blinker connectors and one needed to be cleaned up.
I used a test light on the back of the instrument cluster I have power at the connector from the wiring harness, has power.
Check the back of the gauges and they have power.

I'm at a loss, my gauges(not including speedo) don't work and still no back lights in the dash, Heads lights and blinkers work(the blinker indicators in dash work) I'm going to need to run some universal gauges so I make sure the truck doesn't over heat or lose oil presser.

Most of our trucks only came with the "idiot lights" does your truck actually have gauges?
A pic would really help here.

[basketcase0302]

"Doorjam13"]

The speedo/odo are completely mechanical. For the lights, check the ground. That's my bet, if all the gauges and lights are iffy.
Joseph

This is a dumb question but.... where is the ground for the cluster?

Not a dumb question at all. If memory serves me right it gets its ground by the mounting as I seem to remember having to hold it up against the body for testing years ago. An actual voltage meter here versus a test light will tell you a lot.
I absolutely hate test lights and will never again ever own one of them-threw them all in the trash.
A voltage meter will tell you specifically what voltage the panel is getting, (lighting circuit is a different circuit than the gauges).
Go one circuit at a time here-the dash light to the panel are the easiest to get working first-then the gauges.

[Gregtx]

On many of the electrical based clusters, Ford used this odd little device to step down the voltage from 12v to 5v to power the cluster. Those devices tend to fail on you. It looks kinda like a small relay and is to the far end of the cluster opposite to where the harness enters the cluster. You can take a multimeter and test the voltage coming out of that unit and it should read 5v. If there is no voltage, the device is likely bad. Mac's auto parts sells them, but I found it easier to just go to the 7-11 and buy a USB charger for your cigarette lighter and replace it with that. USB chargers put out a 5v signal and it's not terribly difficult to tear one of them apart and solder wires to the input and output. 12v in, 5v out. It's far more reliable than the stock replacement part (which I believe was basically like a small heater that provided resistance to step down the voltage).