Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

GM 4x4 front axle actuator

GM 4x4 front axle actuator

GM 4x4 front axle actuator


I have a late model (2004) GM 1500 Silverado 4x4 with 4.8, manual transmission, and manual transfer case.

The front axle actuator is controlled by the transfer case switch via the ECM(?).

I want to manually disengage the front axle when the transfer case is in 4-high or 4-low.

My basic thought is to simply control the circuit at the front axle actuator but I am not sure of the ECM implications. Would it be better to control the circuit at the transfer case (hoping this keep the ECM happy).


RE: GM 4x4 front axle actuator

Is there any logic applied between the transfer case switch and the actuator on the front axle?

Try unplugging the actuator at the front axle and see what happens. If you don't get warning lamps, that's promising. You can also try unplugging the switch at the transfer case and see what happens. I have no idea whether the system defaults to "axle disengaged" or "axle engaged", but obviously that's something for you to find out.

If the ECU is applying logic, it may have something to do with disallowing axle engagement if the road speed is higher than X, or some such thing, or possibly using a time-delay between transfer case selecting 4x4 and engaging the axle, to prevent (presumably) dog-clutch shift elements from being damaged by trying to engage at high speed while the other part of the shift element is stopped.

I'd be tempted to fake the system out on the transfer-case-switch side of it, because that way if there is logic involved, at least part of that logic would be preserved.

RE: GM 4x4 front axle actuator

My 99 turbo diesel transfer case has a clutch similar to an AC clutch that gets the front driveshaft spinning before the thermal front axle engages. Thermal unit burned out long ago and is now a manual operation and being in four low without front axle engaged makes for better sharp turns backing into the driveway without the "humping up". Just don't engage the front unless stopped or already the transfer case is in 4wd mode. The thermal front axle unit failed at the most inopportune time possible, stuck in deep sand with license plate for a shovel :)

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close