1966 CJ5 Instrument Cluster Wiring

I just want to make REALLY sure I have this right, I've confused myself, and I have some questions. I've pored over the FSM, searched this board and others, and I am still confused. Can someone complete this table for me?

 

Yes, it is upside down, but I was trying to compare to the FSM.

This thing was connected to nothing - just bolted into the dash and that's it.

9/10 are directly behind a lamp labeled "AMP" on the front face which I assume is the warning light for the charging system? Which wire goes where?

4/5 are directly behind a lamp labeled "OIL" on the front face which I assume is the warning light for the oil pressure. Which wire goes where and how is it connected?

 

I think I found the answer ... obviously I did not search enough:

http://www.earlycj5.com/forums/showthread.php?t=60248&highlight=gas+tank+sending+unit

 

For the AMP wiring, you will have one wire going to the IGN switch that comes hot in the "ON" posit only. The other wire would normally go to term #1 on Delco 10SI alt if that is the one you have. (The 66 V6 stock had the Motorola) The oil light will have one wore going to the IGN switch that comes hot in the "ON" position only and the other will go to the sender on the oil pump. HTH Walt.

 

Just to close the loop on this thread - I think this is what I ended up with:



Thanks for everyone's help!

 

Nicely laid out diagram of instrument cluster. I want to use this right now!

 

Thank you for posting this for our reference years later. I used a Painless 10105 harness to rewire a '66 and must have missed it or there wasn't a power wire supplied for the fuel gauge side to terminal #1. I ran a short jumper from the ignition switch to the gauge and all is right with the world. My pictures of the back side of the dashboard prior to removing the old wires weren't close up enough to that part of the speedometer cluster. I discovered in the process of trying to figure out where the sender and power wires attach that if you get #1 and #3 wired backwards, it makes the fuel gauge peg FULL.

 

I will add to this that unbeknownst to me previously, the power supply that feeds the fuel gauge (terminal #1) appears to also provide the B+ for the engine temp as well. Both of mine came alive suddenly when the helpful chart from Grasshopper was used to confirm wire locations for #1 and #3. Thank you!

 

Wiring is next for me on my 1966, with my Painless kit. Having seen the magic smoke come out of my Omix gauges back when this Jeep was my DD, and as the lucky new owner of this NOS one, I really want to have a solid game plan in place before I wire it up and turn the key.

I am not very electrically astute, so hopefully you guys can help talk me through this. To my understanding, it is critically important that ground the cluster gauge cases prior to any other connections, per this drawing:


Question - there's nothing in the table in this thread in post #7 about the ground - where do you connect a ground wire to the whole speedometer assembly? Or is it supposed to be grounded through the screws that mount it to the dash? With fresh paint like mine - should I consider adding a wire jumper to the ground bus bar I am installing? If so, where would this attach to on the speedo cluster?

Should I also confirm the resistances shown above with an Ohmeter? What are the other possible pitfalls?

Help me not fry my NOS gauge!

 

The cluster is grounded through the dash. Don't run the gauges without a ground - the voltage regulator in the fuel gauge will not cycle on-off without a ground, and that will send a constant 12V to the gauges. This will burn out the gauges after some time.

 

That’s pretty much exactly how I fried the gauges in my omix cluster 10 years ago.

Given that my dash and Tub are both freshly painted, I’m concerned about there being a good ground. I might add a ground wire on one of the screw posts that attach the speedometer and run a leg to my ground busbar below the fuse panel.

 

Put a new shakeproof lock washer under each nut for the cluster. That will cut through the paint and give you a good ground.

 

just to be safe . run a ground wire from of the cluster lugs ( touching the cluster )
to a new ground . that way you'll not have to worry about fresh paint
it only takes seconds . for the magic smoke

 

All of the above advice is correct. Serrated washers, paint scraping, additional redundant ground strap; all good. Ground is like RAM: no such thing as too much!

 

The original speedo cluster had all four mounting nuts with made-on serrated washers, so 4X the chance to ground the gauge to the dash.
-Donny

 

Tim - How could I test that the voltage regulator in my NOS cluster is working properly?

And also - if I wanted a measure of extra protection beyond grounding the case through external lock washers and a separate ground wire, would it do any good to wire in an inline fuse to the fuel sender leg? I will not have any connection to the temp gauge as my temp sender is wired to the Sniper EFI ECU.

 

I presume it will flash a test light on and off about once a second if it's working. If you have an analog voltmeter (like a Simpson) the needle should move back and forth with the regulator switching. A digital meter may or may not show anything sensible, depending on how quickly it samples and updates the display.

I don't think you can pick a fuse that's precise enough to help. Plus the current changes with engine temperature, so what current to pick? The regulator needs a ground to cycle on and off. Without a ground, it stops cycling in the on position. This is bad, since the gauges can't stand to be on at full voltage for very long.

The 7805 or 7806 chip to replace the regulator is a better fix. It's a 3-terminal device, with input at 12V, output at 5v or 6v resp, and a ground. If that loses ground, it goes open and that's perfectly safe. Your gauges don't burn up; instead they just turn off and go to zero.

I would put in a tee at the temperature sender and run two senders, one for each device. No reason to have the dash gauge not work. Or look for another place in the water jacket where you can put a second sender.

 

Thank you Tim.

I love your idea about the temp gauge. Any suggestion on where else to look? A tee seems simple enough, and I could presumably do this without draining all the coolant, right?