4x4 wont engage

[oknik123]

I read all these posts and the same thing is happening to me. The flashing lights on the switches, the click underneath but no engage of 4 hi or 4 lo. I'm going to go look at it right now (my actuator) and see if that's the problem.

 

[raptorforme93]

Nothing appears to be wrong with my switch though. It is always solid on 2wd when that is engaged and just blinks constantly when trying to engage the 4x4. Im pretty sure that front actuator is the problem and Ill probably just go ahead and replace it. Thanks for the help guys! Where should I buy the actuator from??

 

[SunlitComet]

any reputable auto parts store can get them. The one I am eyeing is thru oreily franchise for about $76. They can also sell the upgrade components to change the type used:

Bulletin No.: 76-43-01A

Date: September, 1998
Subject:
Slow or no Engagement of Front Axle when 4WD is selected (Replace Front Axle Actuator)

Models:
1988-97 Chevrolet and GMC K Models
excluding 1988-93 Models over 8500 # GVW

This bulletin is being revised to add information to the Service Procedure, add a new part number, and include schematics. Please discard Corporate Bulletin Number 76-43-01 (Section 4 - Drive Axle).

Condition

Some owners may comment that the colder the outside temperature is, the longer it takes for the front axle to engage when 4 wheel drive is selected, or the front axle does not engage.

Cause

The front axle engagement actuator is a thermally activated component. Because of this characteristic, the time required for the actuator to complete 4 wheel drive engagement is extended as the temperature drops.

Correction

Replace the front axle actuator and include the applicable wiring harness kit. Refer to the Parts Information in order to determine which wiring harness kit is needed.

1996 model trucks with a build date on or after January 2, 1996 are considered as "961". If the build date of the truck is unknown, verify the 3 character "axle code" on the front axle label in order to determine which wire harness to order.

This new actuator uses a motor to engage the front axle and is not affected by temperature. On 1988-93 models with a GVW rating over 8500$, the new actuator cannot be installed and the thermal actuator will remain the service part.



Parts Information

***Graphics removed***



Parts are currently available from GMSPO.

 

[BennyR72]

I'm hoping that most of you have fixed the issue after the last poster put up the TSB. But for those of you that haven't:

The issue is pretty common and simple to fix, and NOT nearly as expensive or time consuming as some of the literate out there would suggest. Dorman makes a replacement actuator (Part # 600-100) that will fit right in, the connector is a little different but instead of buying a new harness like most people suggest you can just replace the connector on the car side (female) for about $8. The other option (which is a good one if you live in a place where it gets cold) is to replace the old thermal actuator with a newer mechanical one (this is what the TSB refers to). Dorman (Part # 600-101) is an upgraded version but requires a new harness to be installed (Part #600-600). It's a bit more expensive to do and a bigger pain in the ass but all in all more reliable.

Hope this helps.

 

[raptorforme93]

I have not fixed mine yet but I will be buying a new actuator in January. I am thinking that I'm just going to put in the old gas style actuator again. I live in Florida so it doesnt get really cold and I only use the 4x4 when Im in mud Thank you for the part numbers and everything though!