Expert: Kevin Pilotte - 5/10/2006

Question
HI JIM, MY NAME IS PAT OHERN.
I LIVE IN HARTFORD CITY,INDIANA.
LAST AUGUST I PURCHASED A 1965 MARLIN WITH 327 V-8,3SPEED W/OVERDRIVE TWIN STICK.WHEN I GOT THE CAR NONE OF
THE DASH LIGHTS WORKED. SO I REMOVED THE INSTRUMENT PANEL TO CHANGE THE BULBS AND DISCOVERED THAT THE PRINTED
CIRCUIT BOARD ON THE BACK OF THE PANEL HAD A BREAK IN IT.
SO I LOCATED A REPLACEMENT AND CHANGED THE CIRCUIT BOARD.
AFTER REINSTALLING THE INSTRUMENT PANEL THE GAS GAUGE AND
TEMP. GAUGE GO ALL THE WAY TO THE TOP??
I WAS TOLD IT WAS A BAD GROUND.
SO I HAD AN ELECTRICIAN BUDDY OF MINE COME OVER WITH A TEST METER AND IT LOOKS LIKE THE GROUND CIRCUIT IS O.K....
DO YOU HAVE ANY IDEAS AS TO WHAT COULD BE CAUSING MY PROBLEMS???????????????
THANKS !   PAT O'HERN


Answer
I can think of tow things to check.
1) CVR (contstant voltage regulator)
2) short in circuit.
Try disconnecting the wire at the tempurature sending unit on the engine. The gauge should go to "E" with the key "on". You can also disconnect the wire going to the sending unit in the fuel tank. The same thing should happen. With the wire disconnected, check it for continuity to ground, there shouldn't be any. If there is, disconnect the harness at the circuit board and measure the wire again for continuity to ground. If there is, there is a short in the wire to ground. If there isn't continuity to ground, the problem is in the circuit board. OR......
As for the CVR, it's a small constant voltage regulator installed on the back of the instrument cluster on the circuit board.It controls voltage to the gauges. If it is bad or missing, it could cause the condition you're experiencing. If you need one, contact an AMC vendor like American Performance or Kennedy AMC. Hope this helps.
Kevin