When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I've got a wire not hooked up to anything on a 72 F100 with the 302. Any ideas what it goes to? It has a style of connector that's normally attached to some type of sending unit. The wire comes off of the 3 wire plug off the firewall. The other 2 wires in this harness that ARE connected are going to the temp sending unit in the front of the intake and the red wire to the coil.
Pardon my ignorance as I've just bought this truck and the electrical system is totally "dead" right now (still troubleshooting) so I can't even see my instrument lights. So these trucks have both a mechanical gauge in the cluster AND a low oil pressure dummy light? The lower driver's side of my block has an oil pressure sending unit, but it has a metal tube coming from it going to an aftermarket oil pressure gauge under the dash. Did the factory oil pressure gauge (not dummy light) in the dash use the same hard metal line setup?
Ok thanks. I'm wanting to get the factory stuff working so looks like I'll be ditching the mechanical oil tube and aftermarket gauge, buying an electrical sending unit, and getting the unit in the cluster working as designed. Thanks!
Someone has removed the original sender and installed an aftermarket mechanical unit. That wire will be for the factory warning light or gauge, whichever your truck was equipped with originally. Solving wiring issues can be a real pita, hopefully it won't be too bad.
Someone has removed the original sender and installed an aftermarket mechanical unit. That wire will be for the factory warning light or gauge, whichever your truck was equipped with originally. Solving wiring issues can be a real pita, hopefully it won't be too bad.
Yeah, it's all starting to make sense now thanks to you guys. When a previous owner makes "upgrades" it's often hard to figure out what is going on!
Have a picture of the existing fitting with tube? Just so you know, the factory setup was an extension from the block, out about three inches and then the bell-shaped sending unit was threaded into that.
The factory extension looks like this: https://www.wildhorses4x4.com/produc...ronco_Oil_Pans and can be made from steel or aluminum. Even though both work, the steel is much better. I can't tell you how many broken aluminum ones I've seen over the years.
Mine actually had a round tube, but since I've never seen a round tube listed as factory even in earlier years, I'm guessing the one on my '71 bit the dust before I got the vehicle and someone had replaced it.
Ford even made some with two threaded holes. This would be most desirable from my standpoint, as you could have both a factory gauge and something else, such as an oil pressure cutoff switch for an electric fuel pump, or an added light, or whatever.
Oh, and the sending units for lamps vs gauges are different. However, I do believe that at least some companies use the same body, so they look identical. If your gauge does not work after installing one, it's either bad, or is for a lamp instead.
Of course, if the gauge does not work after installing the sending unit, it might still be something else entirely. Since none of the gauges work it sounds like(?) then it's probably the IVR (instrument voltage regulator, or "constant voltage supply" per Ford in the old days), or the printed circuit board on the back of the cluster, if your year has that.
Something that all three gauges have in common would be the first culprit to hunt down. That would be the power supply.
But after so many years, nothing says that all three might have had failures of components at different times. Only time and testing will tell the tale.
