Oil Pressure switch and Sender

[67GMC]

I am confused with the wiring on my '84. I have fixed the short circuit that caused the wire melt for the parking lamps. I found the oil pressure sender and the wire. I have a oil pressure switch as well with a two prong blade connector. It has a 2-socket harness. One of the wires was attached (and providing power to the switch) The other wire was just laying there not connected to anything. I'm wondering where it goes to? Does it go to the electric choke line? I already have a red wire on the electric choke heater. Does the switch go in series to stop heating the choke if you have oil pressure (like the engine is running)? Otherwise, my choke heater is always on and heating.

Not sure. Can't find this in the TSM.

Thanks

[tgreese]

Wiring diagrams for that year are a bit goofy, but if you look here http://oljeep.com/gw/elec/84_85/84_85_F ... mPage5.jpg and here http://oljeep.com/gw/elec/84_85/84_85_F ... mPage6.jpg you will see the choke switch and the oil pressure sender resp. There's even a drawing of the choke switch. It's just a switch, with two wires and no connection to ground. The oil pressure sender has one connection and grounds though the body of the switch to the block.

The loose wire is probably for the OP sender. If you ground it momentarily (!) with the key on, the gauge should move. There are colors on that diagram, but it's a bit hard for me to read. The choke switch should have two wires of the same color (since the polarity does not matter) and the third wire for the OP sensor should be another color.

[67GMC]

Thanks TGReese. I saw that on the diagram. I put a line in to the choke heater in series with that OP Switch. I assume the OP switch is closed when no oil pressure and it turns the choke heat on until there is oil pressure (switch should be normally closed when engine off or low oil pressure). I've got an Edelbrock carb but not sure that matters as far as the electric choke goes. I used to have 12V constant on it (with key in RUN). Then I thought it shouldn't get power all the time (only when starting). There were two other wires not used (carb solenoid and carb bowl vent solenoid). I just wrapped those up in the harness.

I may have to get original drawings as the quality on some of these is a little grainy from being scanned. I emailed Tom Collins and he was kind enough to send me a drawing that I didn't have. I'm glad he has put that site up. It's a life saver.

[tgreese]

Thanks TGReese. I saw that on the diagram. I put a line in to the choke heater in series with that OP Switch. I assume the OP switch is closed when no oil pressure and it turns the choke heat on until there is oil pressure (switch should be normally closed when engine off or low oil pressure).

That's backwards, as I understand it. The switch is open when there is no oil pressure, so the choke coil does not heat up when the key is on - only when the engine is running. As the coil heats, the flap opens. It's thermoelectric, adding heat to the hot air from the choke stove in the manifold. The hot air and the coil have to go in the same direction ... hot is open. Test it with your multimeter.

[67GMC]

When I started it, there was 12V at the choke with the OP switch in series...I'm pretty sure it was 0 with the key on RUN but as soon as it was running, it went to 12V. Maybe that is backwards after all!! The Edelbrock site says 12V constant for choke so I guess it's supposed to have power when the engine is cold or hot. Perhaps the stock choke worked different. Maybe I don't need this OP switch thing at all. The sender is working fine. I didn't like the 12V hot wire going through the OP switch and then a wire from there going nowhere. I'll test out a few different ways. Still no HEADLIGHTS!!! but my parking lights work without blowing the fuse every time. I think I lost a ground wire somewhere.

This Jeep is a bit of a headache on the electrical side. Runs great otherwise. I have courtesy lights that come on with the light switch turned counter clockwise but only the rear doors turn the dome lights on. Lots more tracing to do.

[67GMC]

Confirmed-0V with key in RUN. 12V with engine running. It probably is backwards but seems to work now.