1966 CJ5 Instrument Cluster Wiring

Both are variable resistors. Use the resistance scale on your multimeter.

The fuel sender is easy - clip to the sender and move the arm. Watch the resistance reading change. Compare to the spec in the TSM.

The temp sender is harder. I'd heat a pan of water on the stove and measure the temp with a thermometer. Connect the sender to the meter and lower into the hot water. Compare to the spec in the TSM.

Clip leads might help you.

 

Thanks Tim. Just so I understand this more completely - theoretically, what would the risk element be that would fry the cluster gauges? If one of these aftermarket units sends too much current at "hot" or "full" because of having a higher capacity than the OEM?

 

Minimal risk from the senders, which sink current.

The risk comes from the source voltage.

Sources and sinks.

The "senders" don't send, they sink.

The fuel gauge is a 4-terminal device. 1) 12V source to the CVR. 2) Ground sink to the speedometer case and dash. 3) 5V (pulsed) source to the gauge "motor" that moves the gauge needle, and 4) variable resistance sinks to ground (the senders).

The pulser (CVR) is a thermal switch, ie mechanical action. When the switch is closed, current goes through the switch and heats it up. This cause a bimetal arm to bend which opens the switch. With the switch open, the heating stops and the bimetal arm bends back to close the circuit again. Heating starts and etc.

The 5V source is actually the 12V source, but pulsed. However, the ground sink that powers the switch is separate from the sender sink that powers the gauges. If you disconnect the ground, the switch will not run, but the gauges are still connected to the senders. If you lose the cluster ground, the switch will not run and its default state is closed. That's a constant 14V or so to the gauges, which is enough to ruin them.

You may also be able to ruin the gauges by sending the senders to ground for a long time, but I believe it's not nearly as potent a risk as losing the cluster ground.

 

Tim - two questions for you.

#1 - When I have my headlight switch wired up per the directions from the switch vendor:
https://www.kaiserwillys.com/headlight-control-switch-fits-46-71-cj-2a-3a-3b-5


If I wire the AUX dash Light to the one-wire Cluster Bulb #8, the bulb stays illuminated all the time as long as the battery leads are connected, whether the key is in the keyed switch or not. Is it OK if I move the wire to this cluster bulb to the (R) tail light post on the headlight switch, so the Cluster gets illuminated only when the switch is in Park or Lights On?

#2 - I have an electric Oil sender/Gauge pair from Equus plumbed into the block above the oil filter of my V6 and the gauge hanging below the dash.

The sender has two leads - one for the sender <---> gauge and one for a warning light.

I have made this connection, but when I run an 18ga wire from the sender to the Speedometer Cluster bulb #5 (and with switched 12V going to the "hot leg" of Cluster bulb #4, the outside of the bulb housing), the bulb is always on as well. Is this because the engine is off and there is no oil pressure? Will it go out when the engine is fired up and warms up?

 

I would use my multimeter and map the switch. Usually the instrument panel lights come on when you turn on the parking lights, and they stay on when the headlights are lit.

Yes, the OP light should turn off when you start the engine and have oil pressure. Power should go from the ignition (key on) through the bulb and to ground through the sender. If you measure the sender on the bench, the warning light connection should have continuity to the case (to ground).

 

Well that made sense so that’s what I did. Thanks Howard!

 

Howard, can you help me confirm how to wire in my brake pressure switch? In the diagram above it is #19. It looks to me like in this diagram, one leg goes to the "C" post on the headlight switch, and one leg goes to the directional signal group.

My install is obviously different since I have the Painless #10105 kit, and I want to make sure this is how to wire it in to the Sparton (which is currently working on my Jeep). Hopefully we can figure this out for anyone else that ever does a Pinless kit with an OEM Sparton directional.

Here is the diagram from the Painless install directions:



I got some confusing directions from Kaiser Willy's (shocking, I know) so I asked @Fireball who said this in my Build thread (with my comments in RED):

I haven't had the chance to attack this yet, but when I do the above should work, right?

 

I used some wire nuts and followed Fireball's directions with the Painless wires #717 and #718 to either side of the switch and it worked. Cheers guys!

The only thing I don't like is the loose pigtail connection to the posts of the switch that came installed in the proportioning valve. I tried ordering a set of these from JEGS but they were too small. What should I search for at Waytek to find better connectors?

https://www.amazon.com/gp/product/B078WJFGCB/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

The switch looks like this:
https://www.amazon.com/Painless-80174-Pressure-Switch-Pigtail/dp/B00062Z53Y/ref=sr_1_4?crid=2XG1Y5P9OEZZ&keywords=brake+light+switch+pigtail+wiring&qid=1646414190&s=automotive&sprefix=brake+light+switch+pigtail+wiring,automotive,121&sr=1-4

 

I presume you are using wire nuts as a temporary connection.

Presume you have a brake switch that operated from fluid pressure, and screws into the proportioning valve. Yeah, those switches with the flat-top posts are always coming loose. You might design a clip of some kind to hold the connector on. I have thought about soldering wires to the posts. You'd have to be quick and have good prep to avoid damaging the switch. Then you could use a better connector like a Weatherpac or even bullet connectors covered with heat shrink, attached to the flying leads.

 

Yes wire nuts were just for a moment to verify the switch operated correctly to illuminate the taillights when the pedal was depressed.

Yes it's a low pressure switch pre-installed into the PV. I might try a bullet connector with some heat shrink. My PV is on the outside of my frame rail in a spot that will undoubtedly get mud/water from the LH front tire so anything I can do to protect these wires will be beneficial.

 

If you don't like the mushroom type pins and flat connector, you can swap out the switch for one with whatever connectors you want:

• https://www.amazon.com/Beck-Arnley-201-1087-Light-Switch/dp/B000CRVE88
  
• https://www.amazon.com/Painless-Wiring-80171-Switch-Press/dp/B00062Z4WQ
  
• https://www.amazon.com/Allstar-ALL76252-60-120-Pressure-Terminal/dp/B006K8V9LA

 

Doing that would require bleeding the whole brake system again though right? I'm not sure I'm really into that idea given how hard it was to get that done.

 

You would probably have to rebleed just the front circuit, but maybe not since it's on top the block and fluid isn't likely to run out.

 

Putting my Jeep together after an off frame restoration. I have the same question as Chip Addis; which terminal on the ignition switch do these 2 wires go? - both come off the instrument cluster, one from the amp idiot light and the other from oil. Upon disassembly I did a good job marking each wire, just not these 2. After some research my inclination is to put them on the IGN terminal, but I'd like to be sure

 

correct