1972 F100 Ammeter Wiring

[Agolfer7+64]

I have been reading everything I can about wiring the gauges on a 1972 F100 and am thoroughly confused about how to wire the ammeter. One reference recommends using the F350 portion for a 1971, will this work for a 1972? Also how does the constant voltage regulator get into the picture for the ammeter? I purchased a new wiring harness for the vehicle, did not do my homework in enough detail, and am having problems with connectors, gauges,and GM basis. Everything else works well, but way too much excess wire. The truck is a 1972 F100, 82 302 engine, 82 AOD transmission, and 89 E350 serpentine system. Any and all help will be greatly appreciated!!

[bluef250]

Your truck should have a "printed" circuit. This style was used beginning in 1970 and adds more problems to any changes.

Aftermarket wiring harness may help as electrical system age they corrode, etc.

The OEM gauge measures voltage difference between the alternator and the battery and is not very sensitive. This "shunt" system has 2 parallel circuits. One from the alternator that connects to the battery. The other from the alternator through the gauge and then to the battery. Electrical current flows either way through the gauge to show charge or discharge. Most Ford products of the era used the system, none worked well.

The instrument voltage regulator converts system 12 volts then feeds 6 volts to the other gauges. The "ammeter" is not feed from the IVR.

Some possible solutions:
1. Up size the wiring to the gauge and install fuses.
2. Convert gauge to measure voltage.
3. Live with "non functioning" gauge.
4. Install an aftermarket voltage gauge to monitoring the health of the electrical system.

[Agolfer7+64]

I really appreciate this information, I have been looking for it for quite some time. You say to convert the ammeter to a voltage gauge, is there a way to do this using the factory gauge? Is there an aftermarket replacement that fits the stock gauge panel? I would like the more accurate information but retain the original gauge location.

[LACzar]

Try here...scroll down to it...https://www.rccinnovations.com/index.ph ... trucks-all.