Instument Panel Power Source on a 67
 

I don't have any electrical gauges working on my 67. I started the engine today (first time in 31 years after a complete rebuild!!) but I don't have any power to the gauges.

I pulled the instrument panel last month and put it back in recently. The oil pressure gauge works but that's it ( it's not electric ).

Where do the gauges get power from? I have power to the fuse box location for the gauges. I added another ground to the back of the panel to cover that. The assembly manual shows a red wire from the ignition switch, which is getting power, but it goes into the harness and I can't see where it goes from there. I would assume it goes to the fuse panel. I have 4 wires at the ignition switch, black, purple, red and brown.

The instrument panel lights work but that power comes from the light switch.

Any ideas?

The temp and fuel gauges get power when the ignitition switch is in the "on" position, same as the pink wire. The batt gauge is, connected to the horn relay at one end and the starter solenoid at the other. It's a long shunt circuit that makes the batt gauge work and those wires are always hot. There is no single power wire to the gauges.

The battery gauge should work, it doesn't go through the fuses. Try turning the headlights on and see if your gauge deflects to the left a little. You don't even need the key on, it doesn't go through that either.

For the fuel gauge and temperature gauge, the voltage comes from the top fuse in the fuse panel. If you will measure with a voltmeter or test light on the top fuse on both ends (touch your lead to the clips that hold the fuse in, not just to the fuse) with the key on and report back what you get, I think we can narrow this down pretty easily. Don't just look at the fuse, check on the clips.

To make sure you don't have more than one problem, with the key on, touch the green wire going to the temp sender by the thermostat housing to ground (the brass base of the sender will work) and see if the temp gauge moves. It should move to full hot while grounded.

Did you remember to attach the ground wire at the top of the cluster?

If not, the one he added should take care of it. Dash lights work.

Ha! You'll only forget that once!

Ask me how I know...

I keep Dr.Rebuilds O so easy wire diagrams on hand. http://docrebuild.com/oosoez.html

Yes, the top ground is attached.

With the ignition switch on, both sides of the top fuse have power, 11.8 volts. The amp gauge does not move with the lights on and the temp is pegged at 325 (the gauge goes to 250). I grounded the base of the temp sender and nothing happened.

Sounds like a ground. The power to all of the gauges is from different sources and is not working.

On the battery I have the ground cable to the negative post. Is there more than one ground wire to the battery?

Brian, the schematic is pretty good, thanks for the lead on that.

The battery gauge does not use any ground or power source in the cluster. the black and the black white wire on the gauge hook directly to the horn relay and the starter solenoid and nothing else. (They pass through the firewall bulkhead connector closest to the center of the car). I can't say for sure about the 67, but a 65/66 hot battery cable (12v) is BLACK and the ground is brownish red. Make sure which you have connected to ground.
Here's a 65 diagram, the switch and gauge and dash sections should be the same:

https://cimg3.ibsrv.net/gimg/www.cor...d92b80f826.jpg

The horn and solenoid work. I'll check the prongs on the gauges and make sure they are clean. The fuse had some minor corrosion on the two connecting points so I'll clean all of the fuse box and the gauges to make sure I am getting a good connection. I guess at this point I will trace the power from the gauges to the power source.
I don't have the radio or clock installed in the dash yet, can that create a break in the circuit? Checking the schematic above, the ground from the radio and clock go to the instrument cluster. I might have just answered my own question.... I'll let you know how it goes.
Thanks for the help.

That's why I asked you to measure on the clips and not the fuse itself earlier.

They were cleaned before I did the check. Power to both sides of the clips. I didn't do the others but all of them are done now.

It will be Monday before I can get back to the car.

I have power to all of the gauges that are not working. The ground is attached on the top of the instrument cluster and I added another ground from the frame to the backing plate of the cluster. I still can not get my amp, water temp and fuel gauge to work.

Reading the schematic ( I am no electrician) it looks like the final ground for the instrument cluster is the radio ground. I put another ground to the radio case and the gauges still do not work.

Is there a major ground for the radio other than in the radio plug? Where else can the ground for the instrument panel be located? The schematic shows a ground from the radio which then divides into 3 more grounds. One goes to the clock, one goes to the "body connection", where would that be located in the car? The body connection has 11 connections for positive power and most of them go the the steering harness where everything works. A tan wire from the body connector goes to another connector but the page I have the printing is very bad at this location and I can't read what type of connector it is. The 3rd wire from the radio ground is the ground for the top of the instrument cluster. So I think that is where the problem is. If I can find the body connection, I can check the ground there.

I took all of the rear suspension off of the car, removed the dash and instrument panel to repair the oil pressure gauge and rebuilt the speedometer, I removed the gas tank and rebuilt the engine, trans and rear end. The engine runs and I want to drive the car but I won't until I have the water temp gauge working. Is there a ground that I could have left off somewhere in all of that work? I kn ow that is a pretty vague question but I have checked and I don't see any loose wires. What if I run a ground from the battery to the instrument cluster?

Kinda thinking out loud here. I am working by myself and I don't answer these questions because I don't know the answers!!:crazy2:

Thanks!

The black wire coming from the radio connector that has a ring terminal on it and connects to the ground on the bar beneath the glove box and goes behind the radio is the only ground for the instrument cluster and radio and if fact, the entire rear lighting on the car. With all the things you have working, I don't see how it could be a ground problem. Did you physically MEASURE for 12v on the pink wire on the gauges? It also feeds the reverse lights, do they work? I think you are missing a supply voltage that comes up from the fuse panel marked gauges or instr. Disconnect the green wire going to the temperature sensor on the intake and read voltage between the wire connector and ground and post back what you get. With the meter ground wire on ground, does the voltage read + or - 12v? Unless you measure and report back, I cannot go any further with you.

Thanks for getting back to me 65GGVert.

I will check the voltage in the morning. The rear lights, blinkers and brake lights work. There is no back up switch on the trans so the reverse lights are not working. That will be another project for another day, unless I need that to get the gauges working.... I did run a ground from the battery to the back of the instrument panel but that did not work either.

If you have the connector beneath the master cylinder where the backup lights plug in, measure on the pink wire there with the key on and see if you have 12 volts. It's a two wire connector one light green and one pink. measure the pink and tell me if it has voltage and if it's positive or negative voltage.

The battery has 12.09 volts
the Pink Backup light wire is positive 11.91 volts
I ran a direct wire from the battery ground to the ground bolt on the back of the radio and the gauges do not work with the key on.

I removed the gauges put all new lens rubber protectors inside all of the gauges. I'm not sure if that is causing the problem. Or, could the three gauges have been shorted at one time. I had the battery cables off of the battery when I removed the instrument panel and dash.

I'm leaning towards purchasing a new water temp gauge since that is the one I really need in order to drive the car.

I'm afraid I have no explanation for what you have, unless all three gauges are bad. I would doubt that, but it could happen.Unless you connected the gauges incorrectly or possibly if connected the battery in reverse (not sure that would even do it) I have no suggestions.

By the way, connecting a ground to the radio won't tell you anything, the radio is grounded by the black wire, not vice versa. The black wire is grounded to the birdcage and is connected via the three wire connector to the radio, which then grounds the radio. If that ground was bad, adding another to the radio would do nothing. The temperature gauge is about as simple as you could get, 12v to one side and a variable ground (thermistor, which is the sensor) on the other. The battery gauge, as I said earlier, uses neither a supply line or ground to the gauge. The gauge connections go one to the horn relay 12v and one to the starter solenoid 12v and merely displays a voltage drop on a wire connecting those two points together.The gauge doesn't need a ground.

Thanks 65G. I went to Eckler's today and bought a temp gauge. (on sale). I'll see what happens. It just doesn't make sense that all of the gauges have power, the ground is correct. I'll try this gauge and if it works, I will order the others. Ugh, now I have to remove the instrument panel again....

Thanks again for your help.

I went to Eckler's yesterday and purchased a water temp gauge and installed it last night. Today I loosely put the instrument panel back in, connected thebattery, starter switch and temp gauge....turned the key to the on position and VIOLA!!! the gauge worked!

So, somehow, the electronic gauges in the panel were damaged, probably by the battery being hooked up wrong. The last time I worked on the car was 1985 when I rebuilt the engine. The car ran fine after that with everything working. I did something wrong somewhere....

Thanks to 65GGVert and the others that chimed in and offered help. This site is great for solving problems and getting information...

Now I am getting two more gauges ( fuel and battery ) and the car will be on the road this afternoon!!!! How cool is that?? 31.5 years since it rolled under it's own power. Yahoooo!!