Cranks, No start, SKIM Light solid

Discussion in 'KJ General Discussion' started by Stainless, Jul 2, 2020.

  1. Stainless

    Stainless New Member

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    Haven’t had a penny to spend on her, so she’s been sitting. Now, I need to move it to get hooked up to the city sewer, and she won’t start.

    Engine cranks but no start, SKIM security key light stays on solid. The gas gauge doesn’t move — I’m told that means the ECM is grounding out through a sensor?

    Which one, where is it, and can it be made to run without it? I just need to limp a few dozen feet and back again.

    2003, 3.7 V6, auto.

    Any help is much appreciated!
    Thanks!
    -Al.
     
  2. DadOSix

    DadOSix Full Access Member

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    Any codes or engine lights?
     
  3. DadOSix

    DadOSix Full Access Member

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  4. 03GoingStrong

    03GoingStrong Full Access Member

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    The fact that the fuel gague doesn't move, makes me think maybe there is a fuel pump or pressure problem ... or someone has stolen all your gas ... or all the gas has leaked out.
    I haven't faced this issue and not sure where to start. Maybe check for any blown fuses. Maybe there is a procedure for checking fuel pressure on the engine at the fuel rails(?) ... add some gas to the tank maybe. Maybe for what ever reason, it's simply out of gas. I'd have to rule out the simple stuff before jumping into the electronics.
     
  5. DadOSix

    DadOSix Full Access Member

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    Fuel pump quick and dirty

    Quiet truck.
    Key on

    hear it?
    Yes - likely elsewhere
    No - lets start here
    Fuses
    Relay
     
  6. Stainless

    Stainless New Member

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    So, threw about 2.5 gallons of gas in there that I had left over from the snowblower, and I borrowed a code reader: It had P0725 - Engine Speed Sensor Circuit and nothing else.

    I tried the key on/off thing a bunch of different ways, but it wouldn't do anything for me.

    The scanner me clear the code, but that didn't change anything.

    Going to unhook the battery for a while and try again later!

    Thanks!
    -Al.
     
  7. Stainless

    Stainless New Member

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    Checked all the fuses and relays that said anything about fuel or pcm/ecm. Even swapped them for identical parts. Everything seems good.

    Fuel gauge doesn’t move, fuel pump won’t buzz, is there any way to jump the fuel pump directly without dropping the tank? My grand Cherokee had like a bike tire Schraeder valve on the fuel rail that you could just push in and fuel would squirt out if you had pressure... I don’t see one on here.

    Still, it makes sense that the key light being on is the reason for it not starting, rather than a fuel problem.
     
    Last edited: Jul 2, 2020
  8. 03GoingStrong

    03GoingStrong Full Access Member

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    When was the last time it cranked and ran? How was it running then, since before it's been sitting? ... What was the last thing you worked on? Just trying to help you think it through.

    Check connectors at the Engine Control Module (ECM) and Transmission Control Module (TCM) ... look for other connectors that might be loose or not making good contact.

    Since it has been sitting for a while, a low battery COULD throw a P0725 maybe if good "juice" isn't applied to the circuits. Make sure a good battery is charged up and try again. I've seen a battery at end of life and possibly low voltage do some strange things on my Jeep ... been years though. Circuits like good "juice".

    From google ...
    What Repairs Will Fix P0725?
    1. Replace engine speed input sensor.
    2. Replace output speed sensor.
    3. Repair or replace damaged wiring and/or connectors.
    4. Replace solenoids.
    5. Change transmission fluid and filter.
    6. Fix transmission fluid leaks.
     
    Last edited: Jul 2, 2020
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  9. turblediesel

    turblediesel memberable

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    New key battery?
     
  10. Brendon Holt

    Brendon Holt Full Access Member

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    When I was dealing with an ECM nightmare on my old WJ the Jeep would turn over and start fine it would just kill itself after a second or two of running. Took me three days of fiddling to figure out it was bad connections at the ECM that had been jarred from a windshield replacement. Worth checking those connections, like @03GoingStrong said. They can cause all kinds of havoc in my experience.

    Also had a crank-no-start (and dead fuel gauge) on that same WJ from a blown PCM fuse. I know you checked the PCM/TCM fuses but might be worth checking for others that might be in-line and blown, disrupting a critical circuit somewhere?
     
    Last edited: Jul 2, 2020
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  11. DadOSix

    DadOSix Full Access Member

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    For fuel pump - you’ll laugh, but sometimes a good thump will get it moving.

    take a rubber hammer - or your hand, and thump bottom center of tye fuel tank a couple of times. Old school, i know, but it might work.

    some of these libs have a access hatch in the floor boards of the cargo area. Gotta lift the carpet to see the square port.

    a few videos recommend dropping tank. A few open that port.

    with a near empty tank, it might be smart to drop the tank to access the pump.
    Caution, that ring on the top of the tank is a real bear to get off sometimes.
     
  12. jeeptorino68

    jeeptorino68 Full Access Member

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    What kind of condition is your battery in? Poor or old battery can wreak havoc on modern electrical systems
     
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  13. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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    Fuel rail has a schrader valve, out comes a fuel pressure gauge & key on..any pressure?
    [​IMG]
     
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  14. Billwill

    Billwill Full Access Member

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    Skim light being ON solid means that the chipped key was recognised...otherwise the SKIM light would flash ON/OFF and would start before cutting out after about 20 seconds.

    Try remove the ASD relay and jumper female pins 30 and 87 together inside the empty socket...if that works swap the relay over with another one.

    You sure that is the SKIM Led On?

    Early KJs used a "Key" icon instead of a red LED or are you referring to an amber "Key" icon?

    Early KJs you could open the flap on top of the fuel tank without dropping the tank...the floor of the rear cargo can be lifted up by drilling out the pop-rivets at the rear to gain access to the top of the tank. Not sure what years this applies to!

    You can download the 2003 Jeep KJ Service Manual here:

    www.colorado4wheel.com/manuals/Jeep/KJ/
     
    Last edited: Jul 4, 2020
  15. Billwill

    Billwill Full Access Member

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    The key battery..or the seperate key-fob battery...is purely there to lock/unlock the doors.

    The wire ring around the ignition key switch entry point activates the circuit inbedded in the key to extract its code.;)
     
  16. Stainless

    Stainless New Member

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    Howdy! Sorry for no response, I was back at work for a few days. So, I gave up and had it towed in -- Turns out, complete ECM failure, no response at all, even after unhooking all the sensors that could ground it out.

    BUT: The U-Pull near my place had an '03 Rocky Mountain Edition just like mine -- I pulled the Computer, key reader module, lock cylinder and a good key, all for $69 Canadabucks, including core charge for the computer! (Kenny U-Pull in Cornwall, ON - Dead cheap *everything* there! https://www.kennyupull.com/en/car-parts)

    The garage was somehow able to copy/paste my old keys into the new computer, so I didn't even need to swap out the key module or the cylinder, AND my autostart still works.

    Thanks for all the help!
    -Al.
     
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  17. 03GoingStrong

    03GoingStrong Full Access Member

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    Glad you got it sorted and thanks for the update !!! With a complete ECM failure I'm a bit surprised it was still throwing codes. They do strange things when failing I guess.
     
  18. Brendon Holt

    Brendon Holt Full Access Member

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    It lives! Congrats on the fix :)
     
  19. Billwill

    Billwill Full Access Member

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    Glad it is all fixed...at a reasonable price!

    The PCMs/ECMs tend to be pretty robust with most failures being wiring problems but every so often they will fail!;)