1971 amp gauge install
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
How do you know that the 'gauge' is what has failed? Your wiring connections could be defective, someone could have 'cabbaged-up' your wiring, a fusible link could be burned-out, etc.
You could test the meter without removing it from the cluster by locating the two feeder wires to that gauge, disconnecting one of them and momentarily touching a small 1.5v battery to those wires while watching for gauge movement. If the gauge needle moves, the gauge is probably OK. If it does not, you need to remove and repair/replace it.
The simplest place to get to those two wires is at the wiring bulkhead connector on the engine side. If you can read an electrical wiring schematic, you can locate those two wires coming out of the engine bulkhead connector.
I would estimate the odds of the gauge being the problem at 50%; one of the fusible links (there is a 20 awg orange fusible link connected to BOTH of those leads [one is inside the main wiring harness bundle and the other is at the horn relay]) 30%; and 20% probability going to other connected wiring {under dash or in engine compartment}.
It would be a shame to buy and swap out that gauge...only to find out that it was OK and the problem was elsewhere.
You could test the meter without removing it from the cluster by locating the two feeder wires to that gauge, disconnecting one of them and momentarily touching a small 1.5v battery to those wires while watching for gauge movement. If the gauge needle moves, the gauge is probably OK. If it does not, you need to remove and repair/replace it.
The simplest place to get to those two wires is at the wiring bulkhead connector on the engine side. If you can read an electrical wiring schematic, you can locate those two wires coming out of the engine bulkhead connector.
I would estimate the odds of the gauge being the problem at 50%; one of the fusible links (there is a 20 awg orange fusible link connected to BOTH of those leads [one is inside the main wiring harness bundle and the other is at the horn relay]) 30%; and 20% probability going to other connected wiring {under dash or in engine compartment}.
It would be a shame to buy and swap out that gauge...only to find out that it was OK and the problem was elsewhere.
Last edited by 7T1vette; Jun 20, 2018 at 11:13 AM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
Sorry, but that's not the best idea for an early C3 car. The wiring is there for the ammeter; and an ammeter will tell you things that a voltmeter will not...if you know how to read it.
Not sure how the needle broke off (????). Hope it wasn't due to some wild fluctuations with the gauge. You could install a voltmeter; but you would need to re-route some of the wiring as the later C3's had.
Not sure how the needle broke off (????). Hope it wasn't due to some wild fluctuations with the gauge. You could install a voltmeter; but you would need to re-route some of the wiring as the later C3's had.
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Pro
Joined: Apr 2012
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From: Picton NSW
Yes I had mine out a few years back.
Before anything else
FIRST Disconnect the battery, both terminals
When you are ready to disconnect the cables of the back of the gauge ,
mark the cables, so you know which goes where , an easy method to use , get a few different coloured ( Spelling I'm Australian ) zip ties , and draw your self a map of where each wire goes .
Its a good idea to take photos,
Before anything else
FIRST Disconnect the battery, both terminals
When you are ready to disconnect the cables of the back of the gauge ,
mark the cables, so you know which goes where , an easy method to use , get a few different coloured ( Spelling I'm Australian ) zip ties , and draw your self a map of where each wire goes .
Its a good idea to take photos,
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Drifting
Joined: Jul 2015
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From: Catlett VA
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
"Noticed on oil gauge, it's wired. I thought on 71 it was oil line. " This is the back to just show the ammeter location and the metal backing plate that has to come off to replace the ammeter. On my 68 the oil pressure gauge has the small copper tubing. Not sure what year it changed to an electrical sending unit and electrical gauge.
Le Mans Master
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From: Waterford WI