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Engine keeps running when key turned off

Discussion in 'Wrangler YJ (1986-1995)' started by Jjack, Apr 30, 2019.

  1. Apr 30, 2019 at 4:52 PM
    #1
    Jjack

    Jjack [OP] Member

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    New member..hi
    The top white wire is connected to a black wire..If I turn the key off, the motor keeps running..if I disconnect that wire the motor shuts down..with the wire disconnected, the car starts fine although...the gauge reads 13 and pulsates with the signal flasher on..when running, and wires attached, the gauge reads 15, and no pulsing..90 wrangler 2.5..bought it like this..pretty sure new alternator..thanks..

    IMG_20190430_160640885.jpg
     
  2. Apr 30, 2019 at 6:34 PM
    #2
    aggrex

    aggrex Well-Known Member

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    Welcome @Jjack ...a wiring diagram would go a long way with your new purchase. YJ electrical systems are not too complicated compared with current vehicles.
     
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  3. Apr 30, 2019 at 7:21 PM
    #3
    JKBob 25

    JKBob 25 Well-Known Member

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    Welcome to the forum.
    Electrical not my Forte. But as aggrex mentioned. A wire diagram should give you a good idea where that black wire leads to. Post up your find / fix. Could help another member in the future.
     
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  4. Apr 30, 2019 at 7:36 PM
    #4
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    welcome to the site!
     
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  5. May 1, 2019 at 6:14 AM
    #5
    Awrench

    Awrench Well-Known Member

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    Welcome to the forum.... :jeepwave:

    I am comfortable with Jeep wiring - doing it no problem, explaining it not so good. SO-
    Did you do that wire 'twist" when why ?
    Is this jeep new to you?
    Where does that black wire go? Can you see and add a photo?
    The issue just started OR was like this when you acquired jeep?
    Any new or added electrical - alarm, AUDIO, lighting anything added?
     
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  6. May 1, 2019 at 6:19 AM
    #6
    Jjack

    Jjack [OP] Member

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    No. Got it with the wire twist..Black wire goes into harness..Issue was there when I bought it...nothing new added..
     
  7. May 1, 2019 at 7:01 AM
    #7
    Awrench

    Awrench Well-Known Member

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    I will get a wiring diagram and get back to you later-

    FYI those 2 wires are the ALT field wiring/circuit.

    You have been untwisting that splice for awhile? The normal shut down?
     
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  8. May 1, 2019 at 9:25 AM
    #8
    Jjack

    Jjack [OP] Member

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    No, I just started yesterday.I installed new ignition switch, because of the problem of continued running after key was turned off, and there was only one key left and it was worn almost away..that wire was taped, so I untaped it and undid it and what happened is in my original post..thanks for your research..I'll wait to do something else..and follow wires so more..
     
  9. May 1, 2019 at 3:05 PM
    #9
    Awrench

    Awrench Well-Known Member

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    this is a 1990 wrangler? Alt does not look a 1990 series
    Notice the ALT wire colors, could that black wire be a brown wire - color change in photo?
     

    Attached Files:

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  10. May 2, 2019 at 9:51 AM
    #10
    Jjack

    Jjack [OP] Member

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    Nope ..it's black..another question..driver side just past the temperature sending unit is a tall bolt with a lock bolt at the bottom..what ?
     
  11. May 2, 2019 at 10:18 AM
    #11
    Awrench

    Awrench Well-Known Member

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    lets try this - engine off with the alt wires untwisted is there
    12v on white wire?
    12v on blk wire?
     
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  12. May 2, 2019 at 11:42 AM
    #12
    Jjack

    Jjack [OP] Member

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    Key in on position or off?
     
  13. May 2, 2019 at 11:46 AM
    #13
    aggrex

    aggrex Well-Known Member

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    With questionable parts and wiring checking in both modes would be a good idea. Shocking memories come to mind after working on rental properties:eek:
     
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  14. May 2, 2019 at 12:20 PM
    #14
    Jjack

    Jjack [OP] Member

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    Key in on position 12 volts to black, nothing to white..key off..nothing either wire
     
  15. May 2, 2019 at 2:40 PM
    #15
    Jim Beam

    Jim Beam Well-Known Member

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    I am not sure, but there might be a resistance wire that is connected indirectly to the coil. To check, see if that black wire is actually a dark brown and is a single strand and not copper wire. the resistance wire does prevent backfeeding from the alternator to the coil and keeping the engine running when you shut it off. Another check would be checking for a 6 volt reading from the positive terminal on the coil while the engine is running, as the resistance wire is set to keep the voltage down. The later model CJs and early Wranglers used that MotorCraft ignition system. A wiring diagram of the correct vintage should indicate if it is supposed to be a resistance wire.
     
  16. May 2, 2019 at 2:49 PM
    #16
    Jjack

    Jjack [OP] Member

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    I'll check..thanks for the feedback...stand by...
     
  17. May 2, 2019 at 3:42 PM
    #17
    Jjack

    Jjack [OP] Member

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    Can you time this engine? 90 Wrangler 2.5L? I gotta say .not much info on 1990 jeep Wrangler 2.5L out there..they're either well made, or none left...
     
  18. May 3, 2019 at 8:53 AM
    #18
    TJ_abuser

    TJ_abuser Well-Known Member

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    I know that old separate coil motors ie points distributors you could run a wire from neg bat post to neg side of coil and push start it with no key it would run till you pulled the wire off the batt. Mechanical fuel pump so all it need was a spark and crank to run . Possible something is back feeding your coil causing this once the motor starts the altenator provides power as long as it's spinning and energized ie connect to battery
     
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  19. May 3, 2019 at 9:12 AM
    #19
    Jim Beam

    Jim Beam Well-Known Member

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  20. May 3, 2019 at 11:10 AM
    #20
    Awrench

    Awrench Well-Known Member

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    sorry for delay - BUSY !!

    DONALD (JIM BEAM) ADDED A NICE DIAGRAM, same confusion black, brown is what diagrams show. THE 15 OHM RESISTOR WIRE, tHATS GOING TO BE FUN TO CHECK ON - aNYWAY IT RAN WITHOUT WORRING ABOUT THAT,
    YOU CLAIM UNTWISTING THE WIRE WILL KILL ENGINE, i AM THINKING THE VOLTAGE REGULATOR IN ALTERNATOR IS BAD AND BACK FEEDING THE SYSTEM... lETS TRY REMOVING THE 2 RED LEEDS THEY AE A COMMON 12V SOURCE AND SEE IF JEEP STOPS NORMAL.

    sORRY STICKING KEYS
     
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