Problem Solving

I have completed the new wiring harness from Walck's. This all has to do with the oil pressure. There is a purple wire that comes off the harness and attaches to the oil sending unit. That same purple wire then travels through the harness and comes out near the instrument cluster and attaches to the instrument cluster where the oil pressure indicator light is. Back in 1971 the cj5 just had a oil indicator light. However my 1971 was a Renegade ll and had a oil pressure gauge also. The wiring harness did not have any wires to to hook to the oil pressure gauge. So with that being said, can I run the oil indicator light in the instrument cluster as well as the oil pressure gauge? If so how do I wire in the gauge. My gauge is a 0-60 psi, I think original. It has 2 terminals, one that has IGN on a piece of paper attached to it that goes over to a terminal that does not have any letters or anything. How is this gauge grounded? It also has two threaded studs for attaching it to the dash with a bracket. On the bracket there is a light attached to it.

 

These gauges were sourced from Stewart-Warner, just FYI. You can imitate the wiring from an intermediate Jeep to connect them. Look here at the 1974 wiring dagram - Jeep® 1974 TSM online - 22-7. You will see an inset in the top right-center that shows how the ammeter and oil pressure gauge are added to the harness. Focker is correct that the post labeled "IGN" connects to switched power from the ignition switch, and the other post goes to the sender. The gauge is grounded through the case. To use the light and gauge at the same time, you will need to wire them in parallel, and install both senders in the oil galley. This is typically done with a pipe tee. The light sender is an on-off switch, and the gauge sender is a is a variable resistor, so they can't be interchanged. If you knew some electronics, you could make a circuit that turned the variable signal into an n-off signal, but it's going to be easier to install a tee, two senders, and some extra wire.

 

Regarding the Renegade dash gauge, I would verify that indeed the gauge can handle 12 volts directly.
There was a resistor mounted on the firewall that may have dropped the voltage to these gauges.
Someone Renegade smarter than me will have to verify that info.

 

That makes sense to have a different senders for the oil light and the guage. I understand what I need to do now. Did it have 2 senders when it was new? I guess Wyomike would know. Thanks guys. In reading the attachment thing on Timgr post it says that in units that have a oil pressure gauge you do not use the light on the cluster.

 

is the sending unit the same for both the gauge and the light?

I use a mechanical gauge for my setup.

 

No.

The sender for the light is a switch. It turns on and off.
The sender for the gauge changes resistance depending on the oil pressure.

 

No. It is explained above. The oil gauge will require the sender with the proper resistances at d
ifferent pressures. Tim beat me to it....

 

Thanks for all the help.

 

If it was me and redoing it, I would always use a a mechanical oil pressure gauge as well as water temp?

 

x2.

The instant response and real-time behavior of a mechanical gauge will alert me to issues much better than an electric sender.

 

Well, I like the mechanical gauges too, esp. the full-sweep type. Seeing the pressure change with RPM is kinda neat, although IMO an oil pressure light (or alarm!) better protects against catastrophic failure.

It seems the OP wants to put the Jeep back to factory condition, and this is the original electric oil pressure gauge. There should be a matching Stewart-Warner black bezel ammeter, and they mount in the dash to the left of the driver. I'm sure the OP will find that the original OP light is abandoned when the gauge is fitted, and that the wiring follows the same pattern as seen in the '74 diagram. However, there is something different about the Renegade wiring, and it's characteristic of the Renegade. Don't we have a Renegade document that describes the wiring changes vs. the factory '70-71 harness?

 

The RIIs did not have a provision for a light; just the gauge. Someplace on this site is a wiring diagram for the 1971 RII.
If you want the light, in addition to the gauge, you'll need two senders & two wires.
Consider adding the ALT light also.

 

Well so far I have not found the proper sending unit for this gauge. I don't know if the ohms I need is what they are selling these day. I found one on Summit Racing that is a 0-60 psi, 90 degree sweep, 1/8"-27 NPT 240 Ohms resistence. Part # SWW-279D.


Thanks dnb5853

 

I have the same Walack's harness in the orange RI and my plan is to copy the yellow one to add the needed wiring for both the AMP and OIL. I just havent got around to doing it.

My Yellow RII is close to all original as far as the harness is concerned. Although the tub is off the frame and the electrical system has not been tested since I have owned it, I believe that I have the correct sender and will try to get a part # off it the next time I am out to the shop.