Mechanic needs help, NS killing ICM
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 4 of 4
Northstar Engines and System Technical Discussion Discussion, Mechanic needs help, NS killing ICM in Cadillac Engine Technical Discussion; Lo Folks, Just completed a head gasket job on 94 Northstar. Before I started the job the engine had a ...
  1. #1
    Capn Hook is offline Cadillac Owners Member
    Join Date
    Feb 2004
    Posts
    3

    Mechanic needs help, NS killing ICM

    Lo Folks,

    Just completed a head gasket job on 94 Northstar. Before I
    started the job the engine had a miss, I chalked it up to the
    blown gasket.
    But the miss is still there. this apparantly was a pre-existing
    condition. I know what is happening, I just don't know why!!!

    A quick check of the coil packs showed me that cylinders
    1 and 4 were not firing. I checked the ICM terminals where the
    coil pack plugs in and I have power and a ground. I replaced the
    coil pack. Same problem, no spark to 1 and 4.

    I then replaced the ICM and bingo! I had spark to 1 and 4.
    I shut the vehicle off and when I restarted it several minutes
    later, the engine is missing again. And again I have lost spark to
    1 and 4.
    Then I give the vehicle to my electrician and he spends several
    hours checking the signals from crank sensors A and B, cam sensor
    signal etc, etc. Then he installs another new ICM and once again
    we are hitting on all eight.
    I bring the vehicle back to my stall and button it up as it
    pertains to splash shields etc. When I restarted the car, again it
    loses 1 and 4.
    For some reason this car is smoking Ignition Control Modules.
    Although I have power and ground at the coil pack terminals I
    am losing the trigger signal to collapse the field in the coil. At
    one point I did throw a PCM at it to try and bring those cylinders
    back, to no avail.
    Anybody have a clue? Thanks in advance for any help.

    Sincerely,
    Brian K. Ballard

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    Anthony Cipriano is offline Cadillac Owners Fanatic
    Automobile(s): 2004 Cadillac Escalade
    Join Date
    Jan 2003
    Location
    South Florida
    Age
    39
    Posts
    418

    Re: Mechanic needs help, NS killing ICM

    Quote Originally Posted by Capn Hook
    Lo Folks,

    Just completed a head gasket job on 94 Northstar. Before I
    started the job the engine had a miss, I chalked it up to the
    blown gasket.
    But the miss is still there. this apparantly was a pre-existing
    condition. I know what is happening, I just don't know why!!!

    A quick check of the coil packs showed me that cylinders
    1 and 4 were not firing. I checked the ICM terminals where the
    coil pack plugs in and I have power and a ground. I replaced the
    coil pack. Same problem, no spark to 1 and 4.

    I then replaced the ICM and bingo! I had spark to 1 and 4.
    I shut the vehicle off and when I restarted it several minutes
    later, the engine is missing again. And again I have lost spark to
    1 and 4.
    Then I give the vehicle to my electrician and he spends several
    hours checking the signals from crank sensors A and B, cam sensor
    signal etc, etc. Then he installs another new ICM and once again
    we are hitting on all eight.
    I bring the vehicle back to my stall and button it up as it
    pertains to splash shields etc. When I restarted the car, again it
    loses 1 and 4.
    For some reason this car is smoking Ignition Control Modules.
    Although I have power and ground at the coil pack terminals I
    am losing the trigger signal to collapse the field in the coil. At
    one point I did throw a PCM at it to try and bring those cylinders
    back, to no avail.
    Anybody have a clue? Thanks in advance for any help.

    Sincerely,
    Brian K. Ballard

    Did you try a different coil on for those cylinders? It sounds like the coil may be shorting and drawing too much current for the ICM. I know you mentioned replacing the "coil pack" but then this didn't fix the problem. when you replaced the ICM did you use the original coils or the new ones?

    The PCM has no idea which cylinder is firing so it is not likely the PCM. If the crank sensors are reading and the ICM is deciphering the signals from the crank reluctor ring correctly (which it is if it is firing at all) then it is not likely in the crank sensors I wouldn't expect.

    I would suspect the coil at that location or a bad plug wire or plug. Did you check the plug gap? Possible the wrong plugs/misgapped plugs are in the engine causing enough current draw on the 1/4 coil to kill the ICM for those cylinders.

  4. #3
    Capn Hook is offline Cadillac Owners Member
    Join Date
    Feb 2004
    Posts
    3

    Re: Mechanic needs help, NS killing ICM

    Thanks for the info. Yes I did try a new coil but the ICM
    was already smoked. For Monday they are getting me
    new coil, ICM and plug wires, this should fix it. They also
    ordered both crank sensors but I agree with you, the
    car does run so the sensors must be working. Thanks
    again for everyones help.

    Capn Hook

  5. #4
    Anthony Cipriano is offline Cadillac Owners Fanatic
    Automobile(s): 2004 Cadillac Escalade
    Join Date
    Jan 2003
    Location
    South Florida
    Age
    39
    Posts
    418

    Re: Mechanic needs help, NS killing ICM

    Quote Originally Posted by Capn Hook
    Thanks for the info. Yes I did try a new coil but the ICM
    was already smoked. For Monday they are getting me
    new coil, ICM and plug wires, this should fix it. They also
    ordered both crank sensors but I agree with you, the
    car does run so the sensors must be working. Thanks
    again for everyones help.

    Capn Hook
    Yes, if you hadn't tried a new coil with a new ICM then that should show some improvement. Let us know what you find.

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting