Oil, Amp Indicator Lamps And Gauges

Down to the last 2 connections on a total rewire on a 74 cj5 basket case. Used a 20 year old Centech great value wiring kit that came in the box ( no instructions) from p o. He was over his head in the project. The original wiring was, for the most part, removed. It was quite a challenge fabricating the harnesses with original Delphi Packard 56 terminals. From research i found, the 74 came with both indicator lamps and gauges, which is how this one is equipped. The wiring diagram shows the oil pressure sender and the wire through a isolated bulb socket mounted to the cluster then a wire to the "I" terminal on fuel gauge. Seems odd they show a sender connected to a bulb. There is also a separate diagram that shows wiring to the gauge. 2 questions : did both the low o p lamp and the o p gauge work simultaneously from the factory? Is there something I'm missing in the wiring diagram? The amp light wiring seems straight forward with the the wire from the alternator regulator through the isolated bulb socket to the "I" terminal. Would like to keep wiring and components as close to original as possible. Would appreciate any knowledge that could be shared.

 

The oil light is a separate switch that closes on low oil pressure. In my experience there should be a seperate sending unit matched to the
oil pressure gauge to give a variable reading of pressure. My preference is to use a mechanical gauge connected with a braided line
and a split rubber hose sleeved over the line to prevent any chafing.

 

I can say my 74 came from the factory with both the amp and oil gauges. However there was also a working amp light in the instrument cluster but no oil light. The cluster has an oil light listed there on the face of the cluster but there never was a bulb and socket and wire on back of the cluster. I owned two 74 cj5's and both of them came from the factory like this. One of them a 232 straight 6 and the other a 304 v8. There is no reason you cannot have an oil light and gauge too if you want. Just install a "tee" at the oil pressure port on the engine and install both types of senders, one for a gauge and one for the light.

 

Thanks for the replies. When disassembling the jeep, I found the the same thing ol fogie described. No bulb or socket in the low op light cutout in the cluster. I assumed it was missing and interpreted the wing diagram as there being 2 isolated bulb sockets for OP and amp indicators. If I made the op light functional, does it need an isolated socket or would it ground to the cluster with a single wire socket? As for the amp light, does it need the isolated socket and where would the wires connect?Thanks again for the information.

 

You need both insulated sockets as you have to supply ign voltage to the bulbs and the senders are there connection to ground.

 

The amp light connects to the alternator and ignition switch. The oil light connects to the ignition and grounds through the pressure
sensor as the pressure drops. I used a three wire sensor and connected one side to my light and the other side which closes on
a rise in pressure to to the electric choke on the carburetor. This requires insulating the actuating tab in the choke as it can ground
through to the carb. This keeps the choke from heating when just the key is on to prevent opening before starting. That same wire
grounds a fuel pump relay for possible future use. Pump will shut off on loss of oil pressure if the jeep was on it's side. This is the
sensor I used and is adjustable by removing the rubber plug and using a screw driver. I set it at 7-8 lbs. This is probably more than
you want to get involved with and just wanted to show options.


Three wire switch:
https://www.amazon.com/gp/product/B078WHHX41/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

Stock switch:
https://www.summitracing.com/parts/cwa-53005218

Here is a post that shows where to get the the insulated light sockets to fit the stock cluster.
http://www.earlycj5.com/xf_cj5/index.php?threads/158393/

 

I am a firm believer in "idiot" lights. While gauges are nice for monitoring systems, you don't usually watch them, especially when driving. A red warning light lighting up on the dash catches attention.

You will need to run a separate wire for the OP light since it doesn't exist. The wiring is pretty simple.
Wire from ignition side of the key to the light.
Wire from light to the tee'd in sending unit.
That is pretty much it.

 

I can agree with that. I have the oil light in the cluster and a light on the dash.

 

Not trying to hijack the thread, but did certain speedometer clusters NOT have the oil pressure light? My 75 only doesn't have that.

 

A 75 should have one. A small dot on the right side of the head.

There were some later/aftermarket heads that did not have one.

Can you post a picture of yours?

 

Interesting. Here is the one I have.

 

I am not sure when the cluster change occurred. Here is a 1972 that was listed on Craigslist.

 

Mine has the oil pressure gauge and voltmeter, so if that took the place of the lamps.

 

This one also shows gauges but I am not sure if they are factory.