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Thread: Electrical Problems! READ ME!!!!

  1. #1
    Member Hamr25's Avatar
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    Default Electrical Problems! READ ME!!!!

    ok, here is what i got. i have a 98 xj with the 4.0l with 213k on the odo. the biggest problem with the jeep is the alternator. it is only giving off 12.75 volts instead or the 13.75v that it should. now the tricky part is, it will give off full charge at start up and 3-5 minutes after start it will drop off. now yesterday i had it running just fine with 13.75v for around 2.5 hours of driving (from springfield mo to tulsa ok) i hit a bump just outside of tulsa and it has not given out full charge since. now i have come to the idea that this is either the brushes in the alternator are going out, or i have a dead spot in it somewhere that seems to pop up when i hit a bump. now i have let it heat cycle 3 times not since and it will not kick back on line at full charge. so i can almost rule out the dead spot. now the really funny part is i have taken the alternator off of the jeep and tested it and it tested fine at both oriely autoparts and advanced auto parts. in fact i had them both run it 6-7 times each to try and duplicate a failure. and nothing. so if you have any idea on the this matter let me know before i just start swaping parts. part of me wants to thing its the computer (ecu) but i can almost rule that out.

    and my second problem is when i turn on my turn signal my hazard lights flash once or twice and then it goes to the direction that i am signaling. it does not show it on the dash but i have been told this by a few different people.

    if anyone knows anything about either of these problems any and all info will be helpful.

  2. #2
    Snow Jeeper treefrog's Avatar
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    I do not have a 98 XJ manual, but I do have a 98 TJ manual. Not 100% positive that the charging systems are the same, but on a 98 TJ the Electronic Voltage Regulator (EVR) is a circuit board inside the PCM. If your alternator tested good and you have verified that all of your connections are good (check ALL of the grounds), it may be the EVR in the PCM beginning to fail. Low or high charging system voltage will not trip the MIL (according to the service manual), but may cause the "check gauges" indicator to light up if you have one.
    You stated that it will give full charge at startup then start to drop off and that it can change when you hit a bump. That would make me start looking at wiring and connections. The voltage drop off after a few minutes could be happening as a result of a loose/frayed connection building up heat as current passes through the wire increasing the resistance. Also check all fuses and connections in the power distribution block under the hood. Make sure none are loose. Don't be afraid to do the Jiggle Test. (hook up your multimeter leads to the alternator and start Jiggling wires and watch the voltage readings. Just don't stick your hand anywhere you might lose a finger or two) May not be the answer you are looking for, but it will give you a few things to check. Good luck.
    treefrog

  3. #3
    Senior Member HillBillE's Avatar
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    Quote Originally Posted by treefrog View Post
    I do not have a 98 XJ manual, but I do have a 98 TJ manual. Not 100% positive that the charging systems are the same, but on a 98 TJ the Electronic Voltage Regulator (EVR) is a circuit board inside the PCM. .
    BINGO!! The later XJ's are the same. I had a similar problem last April.

    Check your wiring, as mentioned. Look really close, in my case, the outer 'loom' (black corrugated sleeve) hid the spot where the wire's wore through.

    Do you have an aftermarket bumper? If so, was the little round 'vacuum ball' relocated? Mine was, and the common place to elocate them, is near the firewall.

    When the PO relocated the vacuum ball, it was ziptied to the wire harness. It's weight cuased the wire harness to droop, and it rubbed on the fuel injection rail. It cuased 4 wires to ground out, one of which created goofy charging problems.

    I tried a different ECU, and had the same thing. Wasn't until I tracked the wire harness's back that I found the problem.


    There is no voltage regulator inside the alt. A wire from the alt. to the ECU is grounded out inside the ECU when a charge is needed. If this wire is cut/broken, it will result in a no charge situation.

    The ECU also needs "X" amount of volts to allow the engine to un, so if the battery gets low, it may not run, or other wierd electric stuff starts to happen.

    I'm heading to the shop tomorrow, out there I have written down which pin and which of the 3 ECU plugs that is this wire. By jumping it, you will be able to tell if there is a problem in that wire.

    I should be able to post up that info by 1500 CDT WED. (with pics if I remember the camera!)

    HB


    As long as the people remain armed,
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    do so out of duty, honor, oath and love of country.


    "Certified Jeep Junky!"


  4. #4
    Senior Member HillBillE's Avatar
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    Quote Originally Posted by Sentry87 View Post
    and my second problem is when i turn on my turn signal my hazard lights flash once or twice and then it goes to the direction that i am signaling. it does not show it on the dash but i have been told this by a few different people.

    .
    As for this one, it may be related to the charging problem. My XJ ('99) only did this once, when it was extremely wet out, and I had just pressure washed the mud off.
    But after my 4 ways went off (when I signaled a right turn) my Jeep quit. I used my spare ECU to get it running again.

    Once the ECU dried out, it's been fine.


    Check the part# on your ECU. If it's the same as my spare, I can ship it to you to see if that's the problem. (if you can't find one locally)

    HB


    As long as the people remain armed,
    government knows that it cannot rule over the people by force.
    Those who stand in defiance of unconstitutional laws
    do so out of duty, honor, oath and love of country.


    "Certified Jeep Junky!"


  5. #5
    Member Hamr25's Avatar
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    Quote Originally Posted by HillBillE View Post
    BINGO!! The later XJ's are the same. I had a similar problem last April.

    Check your wiring, as mentioned. Look really close, in my case, the outer 'loom' (black corrugated sleeve) hid the spot where the wire's wore through.

    Do you have an aftermarket bumper? If so, was the little round 'vacuum ball' relocated? Mine was, and the common place to elocate them, is near the firewall.

    When the PO relocated the vacuum ball, it was ziptied to the wire harness. It's weight cuased the wire harness to droop, and it rubbed on the fuel injection rail. It cuased 4 wires to ground out, one of which created goofy charging problems.

    I tried a different ECU, and had the same thing. Wasn't until I tracked the wire harness's back that I found the problem.


    There is no voltage regulator inside the alt. A wire from the alt. to the ECU is grounded out inside the ECU when a charge is needed. If this wire is cut/broken, it will result in a no charge situation.

    The ECU also needs "X" amount of volts to allow the engine to un, so if the battery gets low, it may not run, or other wierd electric stuff starts to happen.

    I'm heading to the shop tomorrow, out there I have written down which pin and which of the 3 ECU plugs that is this wire. By jumping it, you will be able to tell if there is a problem in that wire.

    I should be able to post up that info by 1500 CDT WED. (with pics if I remember the camera!)

    HB
    this makes sense. because there appears to be slight reconstruction the the pass side front bumper, i'm guessing it was hit or damaged, so i might. i did drive for 2.5 hours with a tire with a broken belt which shakes like a dog shitting bowling balls. which in turn would/ could cause something to rub/wear a wire or a ground maybe. so i guess i will do a full overlook of the truck tomorrow if the weather is good.

  6. #6
    Member Hamr25's Avatar
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    jeeps fixed and should have plates by thursday-ish
    -We have all put every last dime we have, and every minute of time into this. We have all sacrificed a lot in our lives. Some more than others, some for longer than others.-
    -
    Losers always whine about there best, Winners go home and f#*k the prom queen!
    -Jeep 1: 1998 XJ "Jamie" (sold)
    -Jeep 2: 1997 TJ "Jenna" (stolen)
    -Jeep 3: 1993 Xj "Junker" (sold)
    -Jeep 4: 2003 Tj "Irene"


  7. #7
    Snow Jeeper treefrog's Avatar
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    Quote Originally Posted by Sentry87 View Post
    jeeps fixed and should have plates by thursday-ish

    Glad you got it fixed. What did the problem end up being?
    treefrog

  8. #8
    Senior Member HillBillE's Avatar
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    Quote Originally Posted by treefrog View Post
    Glad you got it fixed. What did the problem end up being?

    X2! Don't leave us hanging!!


    As long as the people remain armed,
    government knows that it cannot rule over the people by force.
    Those who stand in defiance of unconstitutional laws
    do so out of duty, honor, oath and love of country.


    "Certified Jeep Junky!"


  9. #9
    Member Hamr25's Avatar
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    Quote Originally Posted by treefrog View Post
    Glad you got it fixed. What did the problem end up being?
    just bad diode in the alt. i troubleshot (?) the crap out of it, and the only two problems turned out to be the alt and the battery. so the battery got swapped with an optima and i got a mean green alt. from a friend.
    and i will get pics up as soon as i can. besides she looks like crap right now. its been snowing and nasty here for the past week. i need to spray off all the salt and crap soon, i dont need any rust.
    -We have all put every last dime we have, and every minute of time into this. We have all sacrificed a lot in our lives. Some more than others, some for longer than others.-
    -
    Losers always whine about there best, Winners go home and f#*k the prom queen!
    -Jeep 1: 1998 XJ "Jamie" (sold)
    -Jeep 2: 1997 TJ "Jenna" (stolen)
    -Jeep 3: 1993 Xj "Junker" (sold)
    -Jeep 4: 2003 Tj "Irene"


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