No crank, no start, stumped.

Discussion in 'Engine Performance + Maintenance' started by iamthejmsnyder, Nov 21, 2020 at 11:49 AM.

  1. iamthejmsnyder

    iamthejmsnyder Newbie

    Messages:
    7
    Likes Received:
    9
    Joined:
    Jul 24, 2016
    Location:
    Bethel Park, Pennsylvania
    I've been helping my buddy put a new frame under his truck as the old one had rotted away. So the whole cab, bed, front clip, and drivetrain were transferred over to a clean southern frame and were just about wrapping things up. Problem is, when you turn the key, nothing happens. No fuel pump running, no cranking, nothing.

    First thing I did was jump the starter relay to make sure the starter is good. It is.

    Replaced the relay, no change.

    When the key is in the start position, it is sending voltage to the relay telling it to trip but at the same time, something is taking the ground away from the relay, not letting it trip. When the key is off or in the run position, the starter relay has good ground.

    Similar story for the fuel pump. Has good ground when the truck is off, but in the run/start position gets no ground. If I ground it out somewhere else, it works as it should.

    If I jump the starter relay with the key on and the fuel pump grounded elsewhere, the truck cranks, gives a sputter or two, then backfires when I let off but will not start.

    I double, and triple checked that the cab, frame, block, were all properly grounded.

    My best guess was the Security Passlock not letting the engine run. I tried to do the 10 minute reset deal but the "SECURITY" light turns off after a few seconds and stays off for the full 10 minutes with no change afterwards.

    Any insight is greatly appreciated as I am really out of ideas as to what it could be.

    Of all the BMWs and Porches I've solved crazy electrical gremlins in, I didn't think it would be a Chevy Truck that ended stumping me.
     
    HotWheelsBurban and SUBURBAN5 like this.
  2. iamthejmsnyder

    iamthejmsnyder Newbie

    Messages:
    7
    Likes Received:
    9
    Joined:
    Jul 24, 2016
    Location:
    Bethel Park, Pennsylvania
    A few other things I should mention,

    Truck is a 1998 K1500 with 305 and 5-speed.

    We also made sure the cutch safety switch is working properly.
     
    HotWheelsBurban and SUBURBAN5 like this.
  3. SUBURBAN5

    SUBURBAN5 I'm Awesome

    Messages:
    1,903
    Likes Received:
    2,908
    Joined:
    Jul 18, 2020
    Location:
    Houston
    Have you tested the ecm?
     
    HotWheelsBurban likes this.
  4. iamthejmsnyder

    iamthejmsnyder Newbie

    Messages:
    7
    Likes Received:
    9
    Joined:
    Jul 24, 2016
    Location:
    Bethel Park, Pennsylvania
    I have not. The truck ran and drove fine before we tore it apart. What would be the best way to test the ECM?

    I did try plugging in my scan tool and it wasn't able to connect to the ECM.
     
    HotWheelsBurban and SUBURBAN5 like this.
  5. SUBURBAN5

    SUBURBAN5 I'm Awesome

    Messages:
    1,903
    Likes Received:
    2,908
    Joined:
    Jul 18, 2020
    Location:
    Houston
    I dont wanna tell you wrong. I really dont know the answer to that besides a fancy scan tool. Your issue though to me sounds like that. Because the ecm controls a lot of functions in out vehicles. Plus if you physically test all the parts and there all working then to me it points that there just not recieving communication. Now its possible for the passlock. But I could of sworn light stays on and everything at least tries to work, but shuts off right away. That's why I'm leaning towards ecm
     
    HotWheelsBurban likes this.
  6. iamthejmsnyder

    iamthejmsnyder Newbie

    Messages:
    7
    Likes Received:
    9
    Joined:
    Jul 24, 2016
    Location:
    Bethel Park, Pennsylvania
    Ok thanks. Are the ECMs plug and play or is there some programming required?
     
    HotWheelsBurban and SUBURBAN5 like this.
  7. SUBURBAN5

    SUBURBAN5 I'm Awesome

    Messages:
    1,903
    Likes Received:
    2,908
    Joined:
    Jul 18, 2020
    Location:
    Houston
    That's depends I believe yes however I know it has to be same truck same model same year same everything I believe. Blackbear sends you a unit of what you want and then you plug in play. I dont see why a stock unit wouldn't be like that unless it has passlock activated
     
    HotWheelsBurban likes this.
  8. df2x4

    df2x4 Domestics only.

    Messages:
    7,658
    Likes Received:
    4,526
    Joined:
    Mar 1, 2012
    Location:
    Missouri
    They are technically "plug and play" in that they plug in and work, but unless the one you grab is from a truck that's exactly the same as yours you will have issues. '96-'97 are also wired differently than '98+. IMO if you end up needing a PCM it would be much better to order one programed for your application.
     
    HotWheelsBurban and SUBURBAN5 like this.
  9. skylark

    skylark I'm Awesome

    Messages:
    6,369
    Likes Received:
    3,164
    Joined:
    Nov 15, 2011
    Location:
    Grants Pass, OR
    It really sounds like you have a poor ground. Look at a schematic and determine where the grounds are the same. My money would be either the battery cable to the body, the connection at the battery or the cable itself.
     
  10. PlayingWithTBI

    PlayingWithTBI Desert Old Guy

    Messages:
    3,401
    Likes Received:
    2,883
    Joined:
    Jan 3, 2019
    Location:
    Tonopah, AZ
    ^^^X2 - what about the ground strap from the back of the right head to the firewall? A lot of people forget to install it when swapping engines. There's also a ground under the dash near the steering column, IIRC.
     
    HotWheelsBurban likes this.

Share This Page