Converted 65 instrument cluster to 66 5 gauge cluster but have wiring problem!

I have a 65, 289 A code 4spd fastback that I restored into a correct 66 Shelby GT350. However when turning the car on all the gauges go to maximum! Ground issue? We have checked all the wiring and actually have replaced the underwire dash harness with a brand new one and still have the same issue. The 5 gauge cluster is an original set. Any ideas?

Reply to
THE23MAN
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With the senders disconnected?

And you see 5v average, {sweeping} at the Voltage reg?

With batt unhooked, OHM out one at sender connector, like the Oil Pressure, work backwards.

Reply to
Backyard Mechanic

I do not understand your message. Could you please repeat as we are desperate and cannot figure out what the issue may be. Thanks so much!

Reply to
THE23MAN

And I have a 82 Bonneville that restored into a correct 64 GTO.

The gauges are really nothing more than an ohm meter. The sending unit is a variable resistor.

There is a voltage regulator on the back of the gauge cluster that stabilizes gauge voltage to a constant 5v. It looks kind of like a circuit breaker. Did you bypass that during the re-wiring? Check and make sure that the gauges are only getting

5V. If there is 12V, the regulator is bad.
Reply to
.boB

Yes we bought a new voltage reg (the small one that you referred to) and still not working correctly! Any other ideas???

Reply to
THE23MAN

Check it out to make sure it's working correctly. SHould have 12V in and

5V out.

Then check the gauge wiring. Make sure there's 5V into the gauge, and 5V out.

Remove a post from the gauge and see if there's a direct short to ground. Sounds like there's a common ground wire that's shorting all the gauges at the same time.

Reply to
.boB

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