Amp gauge problems.
Senior User
Joined: Mar 2001
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Amp gauge problems.
Hello. My buddy has a 72 f 250 That he is redoing. He bought a wiring harness from painless and it has no wires aloud for the amp gauge. I have tried differnt way of wirering it but nothing works right. First I wired it like this, (Alt output - pos side of gauge - neg side of gauge - fuse box) "The wire harness has the alt output running though the fuse box and back to the selonoid." This would peg the gauge out when you turned the key on. Next I read in the book a little more (Very veg instructions) and it said to do this ( fuse box - pos side of gauge - neg side of gauge - selonoid) this did the same thing. There is a wire that goes to the instrument panel that says "volt meter source, dash power" I ran that wire to the gauge and then ran the wire from the other side of the gauge to the dash. This worked better, it did not peg out the gauge when you turned the key on but it would pulsate almost a half inch on the gauge. I stopped there so I did not burn the gauge up. I figured somebody might know how to wire one of these things up.
Thanks
Chad
Thanks
Chad
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Joined: Jan 2001
Posts: 56,951
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From: Virginia
Amp gauge problems.
I assume you are using the original Ford guage. Some of these guages use a shunt in the original wiring harness. I have never actually seen one of these things, but apparently it creates a small voltage drop in the wiring out at the solenoid, and the original amp guage reads this small voltage and gives a reading. You can get an aftermarket amp guage, and wire it up like you were trying to do previously, or get a factory wiring diagram and the original harness, and hunt down the original connction and shunt, and try to incorporate this into your new harness.
Elder User
Joined: Aug 1999
Posts: 910
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Amp gauge problems.
I've noticed more than one resistance wire or fusible link (not sure of the proper terminology) I suspect one is to reduce voltage headed for the coil, but there is at least another one there coming off the pos of the solenoid on my 76 and 79. I've never seen any appreciable movement on these Ford stock amp gauges.
BBT
BBT
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