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Instument Panel Power Source on a 67

 
Old 03-13-2019, 10:49 PM
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08redrocket
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Default 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?
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Old 03-13-2019, 11:05 PM
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Avispa
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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.

Last edited by Avispa; 03-13-2019 at 11:05 PM.
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Old 03-13-2019, 11:09 PM
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65GGvert
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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.
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Old 03-14-2019, 11:23 AM
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leif.anderson93
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Did you remember to attach the ground wire at the top of the cluster?
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Old 03-14-2019, 11:47 AM
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Originally Posted by leif.anderson93 View Post
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.
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Old 03-14-2019, 05:31 PM
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Frankie the Fink
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Originally Posted by leif.anderson93 View Post
Did you remember to attach the ground wire at the top of the cluster?
Ha! You'll only forget that once!

Ask me how I know...
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Old 03-14-2019, 06:18 PM
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Brian VH McHale
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I keep Dr.Rebuilds O so easy wire diagrams on hand. http://docrebuild.com/oosoez.html
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Old 03-14-2019, 07:28 PM
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08redrocket
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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.

Last edited by 08redrocket; 03-14-2019 at 07:32 PM.
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Old 03-14-2019, 08:22 PM
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65GGvert
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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:


Last edited by 65GGvert; 03-14-2019 at 08:31 PM.
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Old 03-15-2019, 09:21 AM
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08redrocket
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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.

Last edited by 08redrocket; 03-15-2019 at 09:28 AM.
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Old 03-15-2019, 09:48 AM
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65GGvert
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Originally Posted by 08redrocket View Post
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.
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Old 03-15-2019, 05:55 PM
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08redrocket
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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.
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