More wiring help needed.

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RustyDusty
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More wiring help needed.

Post by RustyDusty »

This is how my oil pressure and warning light senders are mechanically installed.
OilSenders.jpg
Q1: Is this the stock arrangement for a 1990?
The two-pronged unit (Oil pressure SW (source: Team Grand Wagoneer)) is currently wired into the electric choke circuit. I am including that page.
SJ8.pdf
This diagram shows that there should be an electric choke switch (front center of engine) controlling the choke. As I have an RB4 intake and other mods performed by PO, I cannot find any such temp switch, and do not know if my oil idiot light is hooked up to anything.
Q2: Could someone help me out with where to look for the temp sensor, and maybe a photo?
Q3: Could someone post a wiring diagram for the idiot light circuit?

Thanks,
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1990 Grand Wag
R4B/Holley 4160
I might lament the amount of grease and oil on the underside, until I think about the lack of rust.

sirrus
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Re: More wiring help needed.

Post by sirrus »

Your pic looks stock, at least mine 88 is the same.

I don’t think there is a light for oil pressure, just the gauge. Wire from oil pressure sender runs to the dash. Oil pressure switch only allows electric choke heater to work when engine is running, doesn’t control anything else. It is the same thing that TSM calls choke switch

There is only one temp sensor - that’s the one that’s wired to the instrument panel. On stock manifold it is on the front right, around vacuum CTO and thermostat housing. I don’t know if you’re talking about that one or something else?
Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 FOR SALE
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tgreese
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Re: More wiring help needed.

Post by tgreese »

The choke is thermo-electric, and heats up both from the engine exhaust and electrically. To prevent the choke from partially unloading when the key is on and the engine is not running, the oil pressure switch is open when the engine is not running. The electric choke switch in the diagram is the oil pressure switch that you also picture. There are 3-terminal and 2-terminal switches, which can have different functionality depending on application. If lack of a third prong bothers you, I suggest you look up the switch you need in the parts books at oljeep.com and search for the switch using that part number. You are more likely to get the correct part that way than by vehicle description.

There may be Jeep (GW?) applications that have an oil pressure light instead of an oil pressure gauge. In my experience with Jeeps, you get one or the other, not both. Possible you purchased a switch for an oil pressure indicator light (not needed) and not an electric choke switch. The choke switch operation is backwards (ie closed when running) from the oil pressure indicator switch (ie open when running). As mentioned, some research with the parts book will help you get the right parts.
Tim Reese
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sirrus
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Re: More wiring help needed.

Post by sirrus »

I’d imagine the 3 prong switch to have one contact NO (choke) and one NC (light), can be checked with multimeter.

Later model GW with rectangular gauges do not have any provisions for oil light on the dash, I though it was the same for round ones as well.

Just out of curiosity - what FSJs came with oil light, except for Kaiser era ones?
Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 FOR SALE
2021 JLU Willys EcoDiesel - new shiny toy
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tgreese
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Re: More wiring help needed.

Post by tgreese »

The choke element draws quite a few amps when cold as I recall. An oil pressure light switch may not be up to it. SMP sells these switches; it's not something you need to go to TGW for. I would urge the OP to look up the Jeep PN and search by that number, not by application.

Yes, likely one tab is NO and the other is NC. You still need the right part.

None that I know of. Gauges in the CJs were optional; you'd get an oil light if you didn't get the gauges. That option appears to have gone away in 1975, when Jeep eliminated the ammeter in the CJ. Even my bare-bones '77 J10 has gauges.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

sirrus
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Re: More wiring help needed.

Post by sirrus »

tgreese wrote: Sun Nov 29, 2020 12:01 pm The choke element draws quite a few amps when cold as I recall. An oil pressure light switch may not be up to it.
When I was rebuilding my carb I've measure the resistance of the heater, it was 2 ohms, that's give you about 6 amps.

Another fun fact about electric choke heater - it is not fused (same as throttle and carb bowl vent solenoids). Add a fuse might be a good idea
tgreese wrote: Sun Nov 29, 2020 12:01 pm None that I know of. Gauges in the CJs were optional; you'd get an oil light if you didn't get the gauges. That option appears to have gone away in 1975, when Jeep eliminated the ammeter in the CJ. Even my bare-bones '77 J10 has gauges.
Good to know, thanks Tim!
Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 FOR SALE
2021 JLU Willys EcoDiesel - new shiny toy

Dr.Bob
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Re: More wiring help needed.

Post by Dr.Bob »

The '86-up uses only the two-prong sender for just the choke; I think the factory connector may have a provision for a third terminal, but it is empty and not used, and no wire goes to it.

The sending unit for the gauge is a single-terminal one.

There is no provision for an oil light in the dash display.
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