Chasing Electrical Gremlin - Help
#3152684
06/19/23 12:52 PM
06/19/23 12:52 PM
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Joined: Feb 2009
Posts: 1,149 NW New Jersey
RSI700VIPER
OP
super stock
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OP
super stock
Joined: Feb 2009
Posts: 1,149
NW New Jersey
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1971 Challenger with Rallye Cluster. Coming back from a show yesterday, I noticed my gas, temp and oil gauge acting erratically fluctuating from max reading to normal readings. Normally I would think to replace the voltage limiter but when the gauges were acting up, the tachometer would drop to zero momentarily. That's the head scratcher. Would a bad dash/gauge ground cause the voltage limiter to send 12 volts to the gauge? Gauges don't peg hard, just climb to max reading a drift from 3/4s to max, then drop to normal for 5 minutes before doing it all over again.
1970 Superbird 440 Six BBL, 4-Speed, Dana, FJ5 1969 Daytona Charger 440 4-Speed, Dana, EV2 1971 340 Challenger Conv. Flemington Speedway Pace Car, FC7 1970 340 Six Pack Callenger T/A 4-speed T8 Tan 1971 340 Challenger RT Formal Roof, EV2 w/ V2 Stripe & Orange Houndstooth 1969 Talladega Torino, 428CJ 1969 Gurney Special Cyclone Spoiler II, 351 Cleveland
"Id rather have a bottle in front of me than a frontal lobotomy" Ben Franklin 1755
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Re: Chasing Electrical Gremlin - Help
[Re: Cab_Burge]
#3153051
06/20/23 01:31 PM
06/20/23 01:31 PM
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Joined: Sep 2003
Posts: 19,408 north of coder
moparx
"Butt Crack Bob"
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"Butt Crack Bob"
Joined: Sep 2003
Posts: 19,408
north of coder
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i have chased dash gauge problems, as well as engine running problems, that finally ended at the tach causing them. check the tach wiring, especially the ground. it could also be where you are picking up the 12v source. check that as well.
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Re: Chasing Electrical Gremlin - Help
[Re: moparx]
#3153056
06/20/23 01:47 PM
06/20/23 01:47 PM
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Joined: Feb 2009
Posts: 1,149 NW New Jersey
RSI700VIPER
OP
super stock
|
OP
super stock
Joined: Feb 2009
Posts: 1,149
NW New Jersey
|
i have chased dash gauge problems, as well as engine running problems, that finally ended at the tach causing them. check the tach wiring, especially the ground. it could also be where you are picking up the 12v source. check that as well. In order for tachometer to function, does it need to get grounder to the dash? I took the car out this morning and everything worked as normal. Very frustrating.
1970 Superbird 440 Six BBL, 4-Speed, Dana, FJ5 1969 Daytona Charger 440 4-Speed, Dana, EV2 1971 340 Challenger Conv. Flemington Speedway Pace Car, FC7 1970 340 Six Pack Callenger T/A 4-speed T8 Tan 1971 340 Challenger RT Formal Roof, EV2 w/ V2 Stripe & Orange Houndstooth 1969 Talladega Torino, 428CJ 1969 Gurney Special Cyclone Spoiler II, 351 Cleveland
"Id rather have a bottle in front of me than a frontal lobotomy" Ben Franklin 1755
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Re: Chasing Electrical Gremlin - Help
[Re: RSI700VIPER]
#3153062
06/20/23 02:22 PM
06/20/23 02:22 PM
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Joined: Sep 2003
Posts: 19,408 north of coder
moparx
"Butt Crack Bob"
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"Butt Crack Bob"
Joined: Sep 2003
Posts: 19,408
north of coder
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tachs usually have 4 wires. 12v source, ground [usually some place on the dash or gauge cluster], a signal wire to the coil [negative post], and a light wire [usually tied into the dash lights so it can be dimmed along with the dash lights to your liking]. chasing intermittent wiring issues can be very frustrating at times. if you have any splices on the tach wires themselves, that is another place to look at. you can fix this ! we can try to walk you through the trouble shooting process, and when the problem is fixed [even if you need to replace the tach] you will have learned something and will be proud to say you fixed it yourself. it took me YEARS [and then some !] and my lifetime up to now, to be able to fix or repair almost anything on a vehicle, and even today, there are times these things pi$$ me off so much i want to take a torch to 'em ! hang in there !
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Re: Chasing Electrical Gremlin - Help
[Re: moparx]
#3153085
06/20/23 04:17 PM
06/20/23 04:17 PM
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Joined: Feb 2009
Posts: 1,149 NW New Jersey
RSI700VIPER
OP
super stock
|
OP
super stock
Joined: Feb 2009
Posts: 1,149
NW New Jersey
|
tachs usually have 4 wires. 12v source, ground [usually some place on the dash or gauge cluster], a signal wire to the coil [negative post], and a light wire [usually tied into the dash lights so it can be dimmed along with the dash lights to your liking]. chasing intermittent wiring issues can be very frustrating at times. if you have any splices on the tach wires themselves, that is another place to look at. you can fix this ! we can try to walk you through the trouble shooting process, and when the problem is fixed [even if you need to replace the tach] you will have learned something and will be proud to say you fixed it yourself. it took me YEARS [and then some !] and my lifetime up to now, to be able to fix or repair almost anything on a vehicle, and even today, there are times these things pi$$ me off so much i want to take a torch to 'em ! hang in there ! If the tach is grounded to the dash, and the voltage limiter is grounded to the dash and both are acting up, then logically the dash ground might be the culprit. Thanks for the great advise.
1970 Superbird 440 Six BBL, 4-Speed, Dana, FJ5 1969 Daytona Charger 440 4-Speed, Dana, EV2 1971 340 Challenger Conv. Flemington Speedway Pace Car, FC7 1970 340 Six Pack Callenger T/A 4-speed T8 Tan 1971 340 Challenger RT Formal Roof, EV2 w/ V2 Stripe & Orange Houndstooth 1969 Talladega Torino, 428CJ 1969 Gurney Special Cyclone Spoiler II, 351 Cleveland
"Id rather have a bottle in front of me than a frontal lobotomy" Ben Franklin 1755
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