Does anybody know the resistance value of the shunt used in the ammeter circuit on an 83 ford F100? I just bought the truck, and I’ve been sorting through all the “experimental” wiring that the last owner installed. There are a lot of wires that are missing including the shunt. I’d like to make it function again if I could.

Thanks.

David -=83 F100 - 300 4spd 4x2=-

 

It really doesn't have a "resistance" value. It is more of a current capacity. It will read "0" ohms on a meter. The size of the cross section (diameter or gauge) is the critical factor. It by-passes most of the current. you are best off getting one from a junkyard if possible.

 

It does have resistance, but it's so low, it's only a factor at high current. You'd probably have to buy a GOOD meter (like a Fluke) to measure it accurately, but basically, I agree with dbc: get a junkyard harness.

 

Or just put in a voltmeter.

 

Steve is technicaly correct about the resistance. But it is so low I doubt even a "good" over the counter meter will measure it. The resistance in the test leads would be higher. The shunt is usually just a calibrated piece of brass about an inch long. Its purpose is to allow most of the current by-bass the meter coil. The actual coil without the shunt measures current in the milliamp range and is easily damaged. If it is used without the shunt it will peg to one side and quickly burn up. If it is in the circuit now and not burned up, It has been bypassed somewhere else or has an internal shunt. Your truck won't work if the ammeter circuit is open.

 

Yes, the resistance is so low, to measure it, you have to do a
4 wire (Kelvin) measurement.

 

The one I took out of my 83 when I put in the '95 engine & alternator was just a heavy piece of wire like all the others in the harness along the R inner fender.