Page 1 of 2 12 LastLast
Results 1 to 10 of 18

Thread: No crank position sensor signal

  1. #1
    Junior Member
    Join Date
    Aug 2018
    Posts
    15

    Default No crank position sensor signal

    Hi guys,
    New to the forum.
    I know you guys have beat this to death in a hundred different posts, but I need your help. Let me start from the beginning:

    1997 GMC K2500. New crate 5.7L with LT4 cam put in (GM Hot Cam?)
    I received the pinout sheet from Lextech, (Thanks again Jeff), picked up a computer, Serv# 12200411, and completed the pin swap.
    Between my mechanic and I, we have been fighting to get CKP signal.
    We have back probed and test the wires to the computer. We have signal to the computer. It's a beautiful, square signal on the scanner. From there, we plug the scanner into the OBDII port in the cab, and we have no CKP signal. I have fuel and no spark. We have checked power, both switched and constant. We have checked grounds. All good. I'm struggling to check through the rest of the wiring due to the fact this girl won't start.

    Two questions: Is there something I'm missing with another component causing the computer to not find the CKP signal? Is there a chance there is a difference between constant ground and key on ground?
    I have tried a second computer. I have replaced the CKP sensor. I have double checked and triple checked any of the wires involving the CKP sensor.

    Again, I apologise for asking something you guys might have answered already.

    Thanks for any help you guys can give.

  2. #2
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    Which CKP and CMP reluctors are you using (how many teeth)...?

  3. #3
    Junior Member
    Join Date
    Aug 2018
    Posts
    15

    Default

    CKP reluctor wheel is 4 tooth. Not sure on CMP, but should be stock.

  4. #4
    Lifetime Member
    Join Date
    Mar 2009
    Posts
    746

    Default

    I'm guessing you already put a 4X 5.7 flash on there from a van?
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

  5. #5
    Junior Member
    Join Date
    Aug 2018
    Posts
    15

    Default

    Yes sir, completed pin swap and had my local tuner guy come down. He flashed the computer and then informed me he couldn't see CKP signal. At that time, I had no throttle position signal either, but I traced that to crossed wires and fixed that issue. I sure with this damn CKP signal was that easy. I've been at this for two weeks already.

  6. #6
    Junior Member
    Join Date
    Aug 2018
    Posts
    15

    Default

    So here's a question.
    How important is it that I use a computer specific to a 2001-02 GMC Savanna van, or do I just have to make sure it has the Serv.# 12200411?

  7. #7
    Lifetime Member ChipsByAl's Avatar
    Join Date
    Feb 2006
    Posts
    617

    Default

    The PCM does not have to be out of a van. Any one with the correct part #'s including the 9354896 can be used. The software including the Operating system and the Calibrations are more specific. Can you possibly post the tune file here.
    Al
    "Trash that carb and get Injected!"

  8. #8
    Lifetime Member ChipsByAl's Avatar
    Join Date
    Feb 2006
    Posts
    617

    Default

    Fuzzman sorry I could not get to you sooner, been busy. Your first post has a few points I need to go over to be sure we are on the same page.

    You have a "beautiful, square signal on the scanner" Are you testing the wiring for a signal at the PCM/crank sensor or looking at data? It sounds as if you are doing the former. Then the scan tool is plugged in the DLC and no crank signal is present. That would be a data input, just like the TPS.

    Next point, you have fuel but no spark. Are you checking at the injectors with a noid light or is this fuel pressure confirmation?

    Al
    "Trash that carb and get Injected!"

  9. #9
    Junior Member
    Join Date
    Aug 2018
    Posts
    15

    Default

    I work at a service shop up here in Canada and one of the mechanics has been helping me try to figure out this mess of mine. We have a Snap On Modis Ultra scanner that we set up to back probe the wires for the CKP, right at the connector for the new computer. Once set up, we turned the engine over and saw signal on the scanner. After that, the scanner was plugged into the OBDII port in the cab of the truck and saw no signal and no engine RPM.
    I started to think the computer was junk, but it still throws the P0335 code. So the computer can't be bad, correct? That's kind of why I was questioning if I need to have the ECM out of a van to match engine and tranny.
    I know I'm grasping at straws here.

    As for fuel, we have tried and tested the wires a few times now and after a lengthy engine turnover, we can smell fuel, so we know we're getting fuel. Didn't use a noid light, but did confirm fuel pressure.

  10. #10
    Lifetime Member ChipsByAl's Avatar
    Join Date
    Feb 2006
    Posts
    617

    Default

    So you probably don't have a correct crank signal, incorrect software in the PCM or bad PCM. You definitely have something coming out of the crank sensor and wiring. Can you use the scan tool and read out the Calibration ID's and Operating system information. The numbers should look like 12212156, 9358554, 9359000, 1282160, 16264444, 16264662 & 9362015. The first three should match unless you have other than a 2002 operating system.
    AL

    PS: I also sent you an email through this forum.
    "Trash that carb and get Injected!"

Page 1 of 2 12 LastLast

Similar Threads

  1. E38 Street Sweeper no start / no crank signal
    By Boost in forum E37, E38 & E67 PFI ECM's
    Replies: 9
    Last Post: September 11th, 2013, 04:11 AM
  2. Knock sensor circuit low signal...
    By VTC_WS6 in forum Gen III V8 Specific
    Replies: 4
    Last Post: July 13th, 2013, 05:58 PM
  3. E38 Crank Position Sensor Relearn
    By hapnermw in forum Gen IV V8 Specific
    Replies: 3
    Last Post: May 2nd, 2009, 03:58 PM
  4. End injection point relative to crank position
    By joecar in forum General (Petrol, Gas, Ethanol)
    Replies: 4
    Last Post: January 27th, 2006, 01:02 PM
  5. I am getting no power to crank position Green B+ wire???????
    By nitrorocket in forum General (Petrol, Gas, Ethanol)
    Replies: 1
    Last Post: September 5th, 2005, 09:22 AM

Posting Permissions

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