factory amp gauge wiring? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ghitch75 · 04-29-2004, 02:47 PM

i have a 75 3/4 ton 4x4 it has a factory amp gauge and the wires for it are 16 gauge with a fuse link in both with 30amp fuses in them...i know wire and amp loads( i work with them everyday) and i can't understand how this could have ever worked without melting the wires in to!!!....i wired to the # 2 wire off the alt to power and it drains the bat down and i know what it dose that.....then i tryed running it though the main power feed to the fuse box and it won't let the truck start( wire to small)...so i'm at a loss on what to do next...anyone seen this before?

NeCrOmAnCeR · 04-29-2004, 04:10 PM

The ammeter on our trucks was not a "true" ammeter in the sense you are thinking. The movement was designed to be used with a shunt. In essence, the gauge is measuring the voltage drop across the shunt, which carries the current used by the electrics of the truck. This is why the wires are so small, the current through them is extremely small.

DrMaserati · 04-29-2004, 04:16 PM

The 16 gauge wire works without melting becasue it is not carrying all of the amperage it is indicating. It's only a gauge to indicate how much current is SOMEWHERE ELSE. The charging current isn't routed through the gauge. It could probably be wired with 24 gauge and work just fine.

What to do next? Rewire it the way the factory had it. It worked that way for 30 years.

ghitch75 · 04-30-2004, 02:11 PM

but that is what i'm asking when the guy before me pulled the motor they cut every wire under the hood i have everything else wired right but it.....so i ask how is it wired?....(i wired to the # 2 wire off the alt to power and it drains the bat down and i know what it dose that.....then i tryed running it though the main power feed to the fuse box and it won't let the truck start wire to small...so i'm at a loss on what to do next.)<from above post

NeCrOmAnCeR · 04-30-2004, 08:49 PM

How do you have the alt and starter wires connected now?? Using some sort of original harness or your own wiring?

ghitch75 · 05-01-2004, 09:30 AM

a little of both

NeCrOmAnCeR · 05-01-2004, 11:56 AM

Where exactly did the previous owner cut the stock harness?

ghitch75 · 05-03-2004, 07:56 AM

they had cut it at the end of the wire loom on the firewall just over the left side valve cover(if your facing it from the hood). the 2 wires going to the gauge one is soild black and the other is black with a white stripe...anyone know how this is to be wired?

ghitch75 · 05-05-2004, 09:21 AM

ok anyone have a manual that would show this or where i can get one?

ghitch75 · 05-15-2004, 02:16 AM

anybody see this or just me?!!!!!!!!!!!!!

04-29-2004, 02:47 PM	#1
ghitch75 Registered User Join Date: Mar 2004 Location: B.F.E. Indiana Posts: 92	factory amp gauge wiring? i have a 75 3/4 ton 4x4 it has a factory amp gauge and the wires for it are 16 gauge with a fuse link in both with 30amp fuses in them...i know wire and amp loads( i work with them everyday) and i can't understand how this could have ever worked without melting the wires in to!!!....i wired to the # 2 wire off the alt to power and it drains the bat down and i know what it dose that.....then i tryed running it though the main power feed to the fuse box and it won't let the truck start( wire to small)...so i'm at a loss on what to do next...anyone seen this before?

04-29-2004, 04:16 PM	#3
DrMaserati Village Curmudgeon Join Date: May 2003 Location: Salem, OR Posts: 75	The 16 gauge wire works without melting becasue it is not carrying all of the amperage it is indicating. It's only a gauge to indicate how much current is SOMEWHERE ELSE. The charging current isn't routed through the gauge. It could probably be wired with 24 gauge and work just fine. What to do next? Rewire it the way the factory had it. It worked that way for 30 years. __________________ 78 Chevy K30 duallie, 454, TH400 78 IH Scout II, 4X4, 345, 727TF 76 IH Scout II, 4X4, 345, 727TF 65 IH 1200C pickup, 4X4, 345, 4 spd 48 IH KB-8-F, RD-450, 5 spd, 35,000 GVW (a REAL truck) "Life is too short to drink cheap beer." Harry S. Truman

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04-29-2004, 04:10 PM	#2
NeCrOmAnCeR Registered User Join Date: Feb 2004 Location: Hodgenville, Ky Posts: 735	The ammeter on our trucks was not a "true" ammeter in the sense you are thinking. The movement was designed to be used with a shunt. In essence, the gauge is measuring the voltage drop across the shunt, which carries the current used by the electrics of the truck. This is why the wires are so small, the current through them is extremely small.

04-30-2004, 02:11 PM	#4
ghitch75 Registered User Join Date: Mar 2004 Location: B.F.E. Indiana Posts: 92	but that is what i'm asking when the guy before me pulled the motor they cut every wire under the hood i have everything else wired right but it.....so i ask how is it wired?....(i wired to the # 2 wire off the alt to power and it drains the bat down and i know what it dose that.....then i tryed running it though the main power feed to the fuse box and it won't let the truck start wire to small...so i'm at a loss on what to do next.)<from above post

04-30-2004, 08:49 PM	#5
NeCrOmAnCeR Registered User Join Date: Feb 2004 Location: Hodgenville, Ky Posts: 735	How do you have the alt and starter wires connected now?? Using some sort of original harness or your own wiring?

05-01-2004, 09:30 AM	#6
ghitch75 Registered User Join Date: Mar 2004 Location: B.F.E. Indiana Posts: 92	a little of both

05-01-2004, 11:56 AM	#7
NeCrOmAnCeR Registered User Join Date: Feb 2004 Location: Hodgenville, Ky Posts: 735	Where exactly did the previous owner cut the stock harness?

05-03-2004, 07:56 AM	#8
ghitch75 Registered User Join Date: Mar 2004 Location: B.F.E. Indiana Posts: 92	they had cut it at the end of the wire loom on the firewall just over the left side valve cover(if your facing it from the hood). the 2 wires going to the gauge one is soild black and the other is black with a white stripe...anyone know how this is to be wired?

05-05-2004, 09:21 AM	#9
ghitch75 Registered User Join Date: Mar 2004 Location: B.F.E. Indiana Posts: 92	ok anyone have a manual that would show this or where i can get one?

05-15-2004, 02:16 AM	#10
ghitch75 Registered User Join Date: Mar 2004 Location: B.F.E. Indiana Posts: 92	anybody see this or just me?!!!!!!!!!!!!!



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