1. #1
    Nucks's Avatar
    Nucks is offline Junior Member
    Join Date
    Oct 2008
    Posts
    15

    Jeep cranks but does not start. No check engine light.

    I have a 96 grand cherokee 4.0 that will crank but not start. With key in run position i get no fuel gauge, volt gauge, and no check engine light. The red light on the dash turns on solid, and the on board diagnostics test does not work at all. A 20 amp mini fuse under the hood blows as soon as i turn key to on position. I replaced the crank position sensor but no change. Do I need to change the PCM?

  2. #2
    SteelHeadz's Avatar
    SteelHeadz is offline Moderator
    Join Date
    Oct 2008
    Location
    Kerrville, TX
    Posts
    6,034

    Re: Jeep cranks but does not start. No check engine light.

    Which fuse is blowing? check the fuse cover for the location of the fuse in question, let us know what that fuse controls.

  3. #3
    Nucks's Avatar
    Nucks is offline Junior Member
    Join Date
    Oct 2008
    Posts
    15

    Re: Jeep cranks but does not start. No check engine light.

    Not sure what the fuse controls. Fuse panel does not specify locations or functions.

  4. #4
    Nucks's Avatar
    Nucks is offline Junior Member
    Join Date
    Oct 2008
    Posts
    15

    Re: Jeep cranks but does not start. No check engine light.

    I believe this is the fuse for the ASD relay but could be wrong.

  5. #5
    Nucks's Avatar
    Nucks is offline Junior Member
    Join Date
    Oct 2008
    Posts
    15

    Re: Jeep cranks but does not start. No check engine light.

    I uploaded a picture of the 20 amp fuse witch blows when i turn the key to run position. I'm having a hard time finding out what it is for. Can anyone help me out with this?
    Attached Thumbnails Attached Thumbnails Jeep cranks but does not start. No check engine light.-dsc00308.jpg  

  6. #6
    SteelHeadz's Avatar
    SteelHeadz is offline Moderator
    Join Date
    Oct 2008
    Location
    Kerrville, TX
    Posts
    6,034

    Re: Jeep cranks but does not start. No check engine light.

    Ok, i'm not sure about this bit it's worth a shot. i'll be more definitive tommorow when i get to work and look for a service manual for your jeep. anywho, i think that you may have a shorted O2 sensor that may blow that fuse. If that's the Fuse 20, that controls the PCM, ASD circuit, 02 sensor circuit and IPC. Check the 02 sensor wires and make sure they are not burnt to the exaust manifold pipe. if they are, disconnect it and install a new fuse and try to start the engine.

  7. #7
    Nucks's Avatar
    Nucks is offline Junior Member
    Join Date
    Oct 2008
    Posts
    15

    Re: Jeep cranks but does not start. No check engine light.

    I'll give it a try after work and let you know. Thanks again for helping.

  8. #8
    SteelHeadz's Avatar
    SteelHeadz is offline Moderator
    Join Date
    Oct 2008
    Location
    Kerrville, TX
    Posts
    6,034

    Re: Jeep cranks but does not start. No check engine light.

    IT IS fuse# 20. Swap the ASD relay with a known good one. Test for the concern. still evident?, remove the fuel pump relay and retest.

  9. #9
    Nucks's Avatar
    Nucks is offline Junior Member
    Join Date
    Oct 2008
    Posts
    15

    Re: Jeep cranks but does not start. No check engine light.

    toaday i checked the o2 sensors. Wires looked ok, but I unplugged them both anyway, replaced fuse, and turned key. The Relays went crazy for a few seconds then settled. Problem went away. So I ran a on board diagnostic test and came up with 12 and 55. Jeep started. Took it for a test drive, all was good right up until I hit a speed bump. Fuse blew again. Replaced it and fired back up, parked her back in garage. I've swaped the relays around before today and got no change, but I belive you are right and there is a bad relay or two in there. Might explain the dead Jeep when i hit a big bump. A bump was the cause of the problem in the beginning as well. So I am going to change all the relays with new ones and try again.

  10. #10
    SteelHeadz's Avatar
    SteelHeadz is offline Moderator
    Join Date
    Oct 2008
    Location
    Kerrville, TX
    Posts
    6,034

    Re: Jeep cranks but does not start. No check engine light.

    Well, i would have to say that's good news that your getting somewhere on this issue. the fact that the fuse blows when you hit a bump, that could be the best diagnostic tool to have. Get a bunch of extra 20 amp fuses. Do the bang and bump test. bump one component at a time until the fuse blows again. wiggle the wiring harness around as well. this should help you narrow it down.

  11. #11
    Nucks's Avatar
    Nucks is offline Junior Member
    Join Date
    Oct 2008
    Posts
    15

    Re: Jeep cranks but does not start. No check engine light.

    just a bit worried that a bad o2 sensor fried my PCM, but if it was the PCM I don't think It would run like new when it is running. I'm gonna go bang and wiggle things around.

  12. #12
    SteelHeadz's Avatar
    SteelHeadz is offline Moderator
    Join Date
    Oct 2008
    Location
    Kerrville, TX
    Posts
    6,034

    Re: Jeep cranks but does not start. No check engine light.

    Although 02 sensors Create's Voltage as they heat up, the PCM has the capacity to tolerate failures by shutting down circuits internally but still let the other sensors function and let the engine keep running. so, no worries here. it's actually more likely to Fry the PCM by disconnecting the PCM connectors and reconnecting it back without disconnecting the negative battery cable.

  13. #13
    Nucks's Avatar
    Nucks is offline Junior Member
    Join Date
    Oct 2008
    Posts
    15

    Re: Jeep cranks but does not start. No check engine light.

    Found it!!!!! In the mix of banging and wiggling things while the truck was running I saw a arc flash near the the top of the manifold. Sure enough there is a black wire feeding the injectors, I believe this it what the wire is doing, that is completely fried. Arcing out on manifold. Checked fuse and sure enough blown and the cause of all my problems. I will upload a picture of this wire to show it's location. Hopefully save others from buying PCM's or CPS sensors in the future. Thanks SteelHeadz.

  14. #14
    Nucks's Avatar
    Nucks is offline Junior Member
    Join Date
    Oct 2008
    Posts
    15

    Re: Jeep cranks but does not start. No check engine light.

    Fried Wire runs to o2 sensor. Just had to keep looking.
    Attached Thumbnails Attached Thumbnails Jeep cranks but does not start. No check engine light.-dsc00313.jpg  

Similar Threads

  1. Check Engine Light
    By LauraBoston in forum CJ YJ TJ and JK
    Replies: 8
    Last Post: 11-21-2003, 12:07 PM
  2. 1997 Jeep Cherokee Sport "Check Engine Light"
    By balloo93 in forum Cherokee, Commander, Wagoneer and Liberty
    Replies: 1
    Last Post: 07-20-2003, 07:00 PM
  3. check engine light??? :(
    By Quik8slvr in forum CJ YJ TJ and JK
    Replies: 5
    Last Post: 07-20-2003, 07:00 PM
  4. what check engine light?
    By Jeeppicus in forum CJ YJ TJ and JK
    Replies: 5
    Last Post: 07-20-2003, 07:00 PM
  5. my Jeep is running rough! Check engine light is on.....
    By Tug-n-pull in forum CJ YJ TJ and JK
    Replies: 12
    Last Post: 07-20-2003, 07:00 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Log in

Log in