Results 1 to 5 of 5

Thread: '94 K2500 keeps blowing 25a front axle engagement actuator fuse(s).

  1. #1
    Join Date
    Jan 2020
    Location
    Trabuco Canyon, CA.
    Posts
    18

    Default '94 K2500 keeps blowing 25a front axle engagement actuator fuse(s).

    Installed new DORMAN 600-100 Actuator (Thermal type) in 2021. Used 4-WD. once or twice since. New fuse blows as soon as key turned "on". Obviously the wiring and or harness or connector(s) or relay(?) etc. may be suspect. I've replaced 3 actuators since 2008 and I'll go a year w/o engaging 4-WD. Any suggestions? Thanks!
    '94 K2500, '82 VW Veggie Cady (sold), Standby: '99 E-350 gasser, Racer: 1964 Front Engine Dragster on E-85.

  2. #2
    Join Date
    Apr 2001
    Location
    CA
    Posts
    13,573

    Default

    Probably a dead short somewhere, or the thermal element itself. Good luck finding it.

    You have alternatives. Update the diff to a modern stepper actuator, or a mechanical push/pull cable. Both are more expensive than replacing the thermal actuator, once.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  3. #3
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,282

    Default

    I would go with the cable system.
    When you need 4x4 you need it......The Thermal systems are sketchy at best...

    POSILOCK comes to mind.

    This setup replaces the thermal actuator completely..........

    When you engage the front end....It's in.....
    You can also use the low range in the T case as a creeper gear on dry hard surfaces by leaving the front end unlocked.........

    I have had the Thermal actuators fail when I needed it BADLY......Had to lay in the snow and replace it......

    No fun...
    The failure of a Mickey mouse gizmo in a MISSION CRITICAL PART is simply unacceptable.......

    When the weather starts looking sketchy I have always taken the time to try the 4x4 in our GM RIGS to be sure they work....

    Just because it worked the last time you used it....does not mean it will NOW...


    Just my thoughts.......

    As Maverick said....Good luck in finding the issue......Try unplugging the actuator and see if the fuse blows....

    Look over the wiring the feeds the actuator and check for damage down around the axle area.....

    The is also a switch on the T CASE that operates the system.....When the 4x4 is engaged in the case the switch activates the system.

    May be the relay......But as mentioned...Sounds like a dead short.....
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  4. #4
    Join Date
    Feb 2000
    Location
    Montana
    Posts
    11,382

    Default

    Disconnect the electrical connectors at the axle, then try a new fuse. This'll let you know if it's at the axle or somewhere up the harness.

    As I recall from re-connecting the wiring on the 6.5 Blazer project recently, the front axle wiring passes across the top/back of the engine, sweeps around the back of the passenger side cyl head, then drops down along the starter before leaving the engine toward the axle.

    The point where it sweeps around the back of the passenger side head is a tight spot where I spent some time getting the harness positioned just right, so it was protected.

  5. #5
    Join Date
    Jan 2001
    Location
    New Hampshire - Live Free or Die
    Posts
    6,057

    Default

    Quote Originally Posted by More Power View Post
    Disconnect the electrical connectors at the axle, then try a new fuse.
    Instead of a fuse, stick a test light in the fuse terminals. When you activate the 4WD, if it lights brightly you have short. And, you can re-use the test light as many times as necessary.
    The Constitution needs to be re-read, not re-written!

    If you can't handle Dr. Seuss, how will you handle real life?

    Current oil burners: MB GLK250 BlueTEC, John Deere X758
    New ride: MB GLS450 - most stately
    Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510

Similar Threads

  1. Blowing gauge fuse
    By JD4755 in forum 1982-2000 C/K Truck & SUV Chassis & Drivetrain
    Replies: 4
    Last Post: 10-15-2009, 21:38
  2. ECM-B Fuse blowing
    By stig in forum 6.5L Turbo Diesel - Tech Support - Troubleshooting - Performance
    Replies: 9
    Last Post: 09-14-2009, 05:26
  3. ECM1 Fuse Keeps Blowing
    By RobK in forum 6.5L Turbo Diesel - Tech Support - Troubleshooting - Performance
    Replies: 2
    Last Post: 12-11-2007, 16:08
  4. Blowing instrument fuse
    By dizzydee in forum 6.2L Diesel - Tech Support - Troubleshooting - Performance
    Replies: 9
    Last Post: 10-30-2005, 02:46
  5. Front drive axle actuator
    By Cooperrw in forum 6.5L Turbo Diesel - Tech Support - Troubleshooting - Performance
    Replies: 2
    Last Post: 06-06-2004, 16:14

Posting Permissions

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