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Where Are The Oil & Temp Sensors?

Discussion in 'Early CJ5 and CJ6 Tech' started by Focker, Mar 17, 2015.

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  1. Mar 17, 2015
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    Or...What Do These Wires Go To?

    I'd like to know if my temperature gauge and oil pressure system/light is working. I could have a bad gauge, sensor or disconnected wire. I've searched but there seems to be a few different places on the engine where they could go??? My wiring looks to be stock and I took a couple of pictures to help assist with my question(s).

    I believe this is a sensor, but which one? The wire color is blue/yellow. It's located on the back right (pass side) corner of the manifold.
    [​IMG]

    This purple wire wasn't connected, just wrapped around some other wires. I looked for an unplugged sensor on the right side of the block and I can't find one. I hand model on the side but this isn't my best work...Sorry.
    [​IMG]
     
    Focker, Mar 17, 2015
    #1
  2. Mar 17, 2015
    Patrick

    Patrick Super Moderator Staff Member

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    The sensor on the intake manifold, blue/yellow wire, is the temperature sender. The purple wire you show is supposed to go to the oil pressure sending unit which should be down on the block above the oil filter.
     
    Patrick, Mar 17, 2015
    #2
  3. Mar 17, 2015
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    Thanks Patrick, that's exactly the help I was looking for. Now I have a better starting point for trouble shooting. At least I had the correct 2 wires, that's a good start. I imagine someone at one time or another removed the oil sending unit. They must have plugged it with a bolt? I'll have to keep looking around in that area for it.
     
    Focker, Mar 17, 2015
    #3
  4. Mar 17, 2015
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    I think I finally found it!
    [​IMG]

    This thing is crusty.
    [​IMG]
     
    Focker, Mar 17, 2015
    #4
  5. Mar 17, 2015
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Yreka!
     
    timgr, Mar 17, 2015
    #5
  6. Mar 17, 2015
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    or Ureka!
     
    Walt Couch, Mar 17, 2015
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  7. Mar 17, 2015
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    You're telling me.

    If been searching for this thing off and on for months. I was determined to find it this time since my fuel gauge is now working. Might as well try to get the stock temp gauge and oil light working too.

    More crust than a Costco apple pie.
    [​IMG]
     
    Focker, Mar 17, 2015
    #7
  8. Mar 17, 2015
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    480 seconds in the Harbor Freight sonic cleaner...Love that thing!
    [​IMG]
     
    Focker, Mar 17, 2015
    #8
  9. Mar 17, 2015
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    The oil press switch is really just an "OFF"/"ON" switch. With engine not running (no pressure) the switch is closed (connects the wire to ground) and turns "ON" the OIL light. Anything above about 4 lbs and the pressure switch opens and turns the light OFF.

    The TEMP sender is a special resistive switch designed for these gauges. Be sure you have the right value switch.
     
    Walt Couch, Mar 17, 2015
    #9
  10. Mar 17, 2015
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    Focker, Mar 17, 2015
    #10
  11. Mar 17, 2015
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Easiest test on the OPS is try it. Light should come on with the key on, and go dark as the engine starts, then light again when you shut off the engine. Pretty simple.

    For the temp sender (thermistor) the ohm values at specific temps will be in the FSM. Try it at room temp an then dunk it in boiling water and measure again. Or just try it. Typically they work or they don't.

    If you need them, buy the replacement that the RockAuto catalog specs. They show a repackaged Standard PS10 OPS on closeout for $1.18. And a Standard TS4 for $8.22.
     
    timgr, Mar 17, 2015
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  12. Mar 17, 2015
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    Just tested the OPS...You're a stud and I'm an idiot. I used thread dope and the light didn't come on. Then a light when on in my head...It needs a ground. Cleaned off the dope and Yreka - Ureka it works!

    I checked there but didn't know what to get, but if you say it's the one, then I'm Ordering. For quick and down the street, will one of the Napa one compare to the TS4?
     
    Focker, Mar 17, 2015
    #12
  13. Mar 17, 2015
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    It's under "cooling" on the RockAuto page.

    If you want a Napa number, try going to napaonline.com and either look it up by application, or enter TS4 and get a cross to it. Should be easy - it's a GM part. Or the Napa counter person should be able to cross to TS4.
     
    Last edited: Mar 17, 2015
    timgr, Mar 17, 2015
    #13
  14. Mar 18, 2015
    Rick Whitson

    Rick Whitson Detroit Area 2024 Sponsor 2022 Sponsor

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    Eureka , is the word you are looking for, I live six blocks off Eureka Road. Not that I am a spelling ace.
     
    Rick Whitson, Mar 18, 2015
    #14
  15. Mar 18, 2015
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    It could have been worse...Urethra!

    I suppose the next thing you're going to tell us is that a Tycoon isn't a severe tropical storm? ;)
     
    Focker, Mar 18, 2015
    #15
  16. Mar 18, 2015
    Drive28

    Drive28 Member

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    Got me laugh'n:p
     
    Drive28, Mar 18, 2015
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  17. Mar 18, 2015
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

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    r)r)r)r)r)r)r)r)r)r)r)
     
    47v6, Mar 18, 2015
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  18. Mar 19, 2015
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    A local parts house had a TS4 but the threads are too small.

    Edit -
    Here's mine next to the TS4. I bought a TS6 which fit my manifold but decided to go get the TS4 and maybe get some type of adapter??
    [​IMG]
     
    Focker, Mar 19, 2015
    #18
  19. Mar 19, 2015
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Huh.

    Have you tested this sender with your multimeter? Looking at my '72 manual, it says a temperature sender unit should read 72 ohms cold (100F or below), 23 ohms at 161F, and 9 ohms at 250F. Boiling temp is about half-way between 250F and 161F, so the change should be about half the difference between 9 and 23 ohms: 16 ohms at boiling. But get the numbers from your FSM and use those. If you need help with the math, tell me the numbers and I'll give you value to look for at boiling temperature.

    I suggest you test this sender, and if it fails, get the TS4 from the store and see if it passes the test. Then buy a bushing from the hardware store to make it fit. There aren't that many sizes of pipe thread (NPT). I think you'll need a 1/4" female NPT to 3/8" male NPT bushing.

    Does the temp gauge needle move toward hot if you touch the wire momentarilly to the engine block?

    If the sender you have passes the multimeter test, you need to look at the other end of the circuit, ie the gauge and little voltage regulator thingie. Does your fuel gauge work? It's connected with the temp gauge in the cluster. Other guys here (maybe Howard?) are more knowledgeable about the guages and regulator thingie.
     
    timgr, Mar 19, 2015
    #19
  20. Mar 19, 2015
    Focker

    Focker That's a terrible idea...What time? Staff Member

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    Thanks Tim, I was doing an edit at the same time.

    I suck with voltmeters but here's what I can tell you. I have an analog tester with a 1K OHM setting. I tested the old sender at room temp by placing the tester's probes on each end of the sender and then in boiling water.

    Both times the needle was the same = 2.
    [​IMG]

    I tested the TS4 and at room temp it reads = 2 (or just a hair past but not to the 1st dash). At boiling it reads to the 2nd dash. I told you I suck at this. I have a digital meter but the 9volt battery is dead. :oops:

    My gas gauge does work...In fact all of it works but I'm not sure about the temp gauge. I can't run the engine right now because I pulled the radiator. Can I risk heating the end of the wire with a lighter and watch the temp gauge to see if it moves?
     
    Focker, Mar 19, 2015
    #20
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