going from warning light to guage in cluster

[1972hiboy]

Hey guys. Im spending some time on my crew project and we are diving into the wiring. The crew ( a 72 4x2 fe/c6 f350 srw) had a guage cluster that only had fuel and temp guages, the charge status and oil pressure were warning lights. I had taken that guage cluster apart and installed factory ammeter and oil pressure guage from another good used cluster. originally I was planning on running the wiring harness from the same donor truck but it looks to be ill be repairing the exsisting harness in the crew. My question is. Im pretty sure that for the oil guage to work correctly I need to replace the oil pressure switch with a oil pressure sender. However, Im not certain on how to make the ammeter work correctly with a guage on a wiring harness that was setup for a warning light. Has anybody done this conversion before? it could be a real possibility that since so few original ammeters actually seem to work that maybe I should just leave the warning light setup and be done with it?? I do have the donor harness from the truck that had been wired for a charge guage that I could remove sections of. The goal in all of this was to have a full cluster of real guages vs go or no go lights because I do check my guages while driving and like to know whats going on. Oh almost forgot,the donor wiring harness came out of a 1972 f250 4x2 fe/c6 Any input is appreciated.

Rich

[1972hiboy]

bump, any takers?

[two-bit]

With the oil pressure you are correct. replace the switch with a sender.
As far as the amp meter goes..... I would find some schematics and compare them. I know they are around here somewhere.
Looked at them more than once myself. They will probably tell you the difference, and what you need to do for the conversion.

Good luck
Two-bit

[BobbyFord]

Alternator harness is different between gauge trucks and dummy light trucks.

[1972hiboy]

Thanks for the input guys! Thats great info about the alternator harness Bobby. Ive looked over the wiring diagrams but the one for 72 looked like one big diagram pretty generic for everything. But I believe the big difference is the ammeter trucks used a shunt in their harness where the warning light trucks did not? perhaps this difference is in the alternator harness?

[BobbyFord]

Thanks for the input guys! Thats great info about the alternator harness Bobby. Ive looked over the wiring diagrams but the one for 72 looked like one big diagram pretty generic for everything. But I believe the big difference is the ammeter trucks used a shunt in their harness where the warning light trucks did not? perhaps this difference is in the alternator harness?

I don't remember exactly how, but the harness is wired differently. I remember this from almost 20 years ago when I switched clusters on my F250. I also swapped alternator harnesses.

[Nitekruizer]

I can't tell you exactly what you'll need to do. Yeah, the Oil Pressure switch will have to be replaced with a sending unit and the trucks with Gauges are wired differently at the Alternator and at the VR. The trucks with gauges do not have a connection to the Stator terminal of the alternator. AFAIK, they use the same VR, just connect differently. The "I" terminal on the VR is not used if the truck has a gauge. I seem to remember that the Ignition Switch may be wired in to the harness differently too.

[skblixt96]

1972hiboy, have you gotten anywhere with this? I'm looking at doing the same.

Shan

[1972hiboy]

Hey Shan. I ultimately decided I did not want to alter the wiring harness that much and chose to leave the warning light. Most of these era trucks have had the wiring harnesses altertered so much that I havent seen many ammeters that actually work. So if I at least have a functional warning light that gives me a indication of alternator failure with a go or no go light, Ill take it.