Thanks for the info. Let me know if there's a picture of your custom, custom cab cluster somewhere. I tested mine this morning and all lights, turn signals, and high beams all function but I have no high beam indicator light that I can see. I'm confident it's there but I'm going to have to find it next time I pull the cluster out. I have the base model wiring which includes separate turn signal lights which function correctly. I can leave those alone. When I find the high beam indicator I'll probably just fabricate a hole for that one. Resto-mods-R-US haha.. thanks supersaber!

 

According to my wiring diagram, the high beam indicator light wire should be green with a black trace. For what it's worth, the Ford factory engineering number (not the part number) stamped onto the harness I mentioned that you need is
C5TB-13A357-B. Maybe Number Dummy can use that to find you one of those harnesses somewhere. Unfortunately, I haven't gotten around to uploading any pictures of my truck. I'm gonna try to do that if/when I ever get it finished.

 

Thanks, everything helps. I'm looking forward to seeing some pictures of your truck when you are far enough along. I'll post some more pictures of my cluster when I get the oil pressure gauge going. Camperspecial65 has the part (adapter that threads into the block) I need. Then I think I will have all the parts I need to get that going. Maybe spray some WD40 on the odometer haha..

 

Why were some of the 66 F100 manufactured with the different Instrument clusters

 

Different models offered different custom interior features. For example, four wheel drives, F350, F500, F600 had painted instrument clusters and F100, F250 had different options.

 

Have a question about the 66 Custom cab oil pressure gauge....can the idiot light and the oil pressure gauge operate from the same wire running to the sending units?
How do you test an oil pressure gauge to see if it works?
thanks!

 

37 Ford Guy: When your truck has both the oil pressure gauge AND the warning light, there are TWO separate senders (both screwed into a single combiner fitting) with TWO separate wires leading to the instrument panel. The larger of the two senders is for the gauge. The smaller sender is for the warning light. At least one of the wires is white with a red trace. I don't know if both are. The wire from the sender goes to one side of the gauge. The other side of the gauge has a black wire with a green trace that goes to the instrument panel constant voltage transformer. So have you started the engine, checked that all the wires are connected to the right things and get no indication on your oil pressure gauge? Searching way back in my memory (so don't hold me to this) I think that you can check gauge function by disconnecting the wire at the sender, grounding the wire out somewhere (like on the block), and turning on the ignition key. (This takes two people to do.) Don't start the engine. With the wire grounded the gauge should move to the 80 psi position. If that happens, the gauge and the wiring are OK and the sender would seem to be the problem. Those senders aren't horribly expensive and are easy to come by. By the way - does your oil pressure warning light work? Hope this helps.

 

Hey Super, thanks for the response! My truck originally had the warning light only. I recently acquired the sweep cluster with the auxilliary gauges. I also have the adapter for both sending units.
You may recall I've recently swapped a 5.0EFI engine into my truck. The Ford Racing aftermarket wiring harness has provisions for the oil pressure gauge built into it. I left the original wire to the warning light connected and connected the oil pressure gauge to the new wire in the harness. I installed a new sending unit and also ran the black/green wire to the appropriate place but the gauge isn't working. For what it's worth, the new harness also has a new wire for the temp gauge and it works fine.

I was just trying to figure out if the gauge is bad or if there's something in the new harness that would keep it from working with the old gauge.
I'll experiment with your test and see what happens.
thanks!

 

Make sure the stand-alone ground tang for the cluster body near the middle in back is well grounded. Use a multimeter to ensure you have continuity and are getting voltage to the gauges.

AFAIK a 5.0 liter EFI engine was not a slick sixties F100 or F250 option. Therefore it's possible that the sending unit on this engine is incompatible with the custom cab sweep-speedo IC oil pressure gauge. If true you will need to replace the gauge with the same size that is compatible with your sender. Good luck with it!

 

Really?? It looks like it belongs in there!!! Actually, I bought a new sender that is correct for the F100 gauge, not the one from the Mustang. The warning light is connected with the original F100 wiring and it works fine. The oil pressure gauge is connected to the sender via the wire built into the new EFI harness and it doesn't work. That's why I was asking if both sending units could operate thru the same wire. If so, I could splice an extra connector onto the orignal F100 wire that goes to the warning light. That would eliminate the possibility of something in the EFI harness keeping it from working. I still need to perform SuperSabre's test on the gauge. Haven't had time to do it yet.
Thanks for the info!

 

I think a 302 is a nice engine for these trucks, but I don't think the 302 was introduced until 1967-68. A compatible sending unit should work well. If the gauge is getting voltage when it should be then it could be a bad gauge. I swapped out a bad fuel gauge on a round speedo once and got it going.

 

If my test doesn't work out, I'd think it would be easy enough to run a test separate wire from sender to the O P gauge to check the wiring, etc.. Since you said your new instrument cluster coolant temp gauge works fine, and the O P warning light works fine (what about fuel quantity?), it doesn't sound like there are any issues with the I/P constant voltage regulator or the ground. In this scenario, the gauge gets its signal from the sender via the wire, and the power comes into it from the other side from the I/P voltage regulator. Two other observations: When you try my test, allow a reasonable amount of time for the needle to start to move after you have grounded out the wire. And second, I remember reading somewhere that Ford desensitized the Mustang O P gauges after the '60s because customers worried about them too much. Can't say for sure how true that is, but that's what I remember hearing. Since you bought a new '66 O/P gauge sender (you're SURE they sold you the correct one?) that shouldn't be an issue. Don't forget, with your new cluster, there's only ONE green turn signal light for both directions, so unless you install your own TWO LEDs, you'll have to make a combiner to turn two turn signal wires into one - easy enough to do. I'll throw in a picture (now that I've finally figured out how to do it) of my cluster with two LEDs for turn signals.

 

Hope I'm not overdoing this, but I found a picture of the two senders. The warning light sender is on the left and the gauge sender is on the right. Sorry the pictures are so big. Somebody will have to teach me how to make them smaller.

 

Thanks, Saber. My truck is a custom cab so I already had the sweep cluster, just no extra gauges. I swapped it out for one with the gauges. I look forward to testing the gauge but probably can't do it till Saturday. Will let you know what I find out.

On the new OP sending unit, the guy at Oreily's showed me his computer screen with a pic & part# for '66 F100, so according to them, it's correct. I compared it to the old one when I got home and there is a difference in the size of the hole that measures the pressure. The old one has a bigger hole. Don't know if that matters or not. Won't know till I test the gauge itself.

Regarding the fuel gauge, I bought the '66-'68 style Mustang tank prepped for EFI in-tank pump. I also bought the new sending unit with it that is supposed to be the proper ohms,etc to work with my original gauge. I followed their instructions for installation and everything seemed to be working fine but I filled the tank full for the first time today and the gauge doesn't register above 1/4 tank. It worked perfectly before the swap. I hope I don't have to drop the tank again!!

 

That's the same setup I have except it screws into the block on the 5.0.