Okay fellas, i need help with this now, i swear if it aint one thing its another,
now...i seem to be blowing the 4X4 fuse everytime i engage the 4WD in my truck.
i checked all the wires and dont have short what would be causing this.
The front actuator is causing the fuse to blow. To check, disconnect the wire leads to the front actuator and try your 4wd. If the fuse don't go bad then replace the Actuator.
The Actuator is a thermal solenoid and is know to cause issues in the cold as you are experiencing and other GM owners such as your self. There is a front actuator replacement update that GM has which is not a thermal solenoid.
On the full size, the front actuator is electric, not vacuum.
When in 4wd mode, a switch on top of the transfer case conducts 12 volts out to the actuator. Wire #50 (brown) is the 12v feed, and it conducts to the light blue wire (#900) to the actuator.
When shifted out of 4wd, the switch opens up and no voltage goes to the actuator.
I'll assume it is the actuator, if the plug to the actuator is getting 12 volts when in 4wd.
The way this actuator works, is it is a sealed chamber that gets heated by voltage. When it heats, the pin in the end swells and pushes a shift fork in the front differential. The shift fork engages a spline on the passenger side of the differential, and boom! you have 4WD.
GM offered an upgrade to this actuator that is a motor instead of a heated device. However, it requires a small harness addition, a spacer, and a new actuator. It is about a $150 to $200 option.
Good luck. The actuator is usually the problem 90% of time but recheck all of the wire harness just to maker sure there is no short before replacing any parts. The actuator may not be fully engaged or disengaged and the fork to the spline may be what is causing the whining or grinding noise you hear.
88-UP C/K ACTUATOR UPGRADE
VEHICLE SERVICED: 1994
CHEVROLET FULL SIZE
PURPOSE: IMPROVE AXLE CONNECT ENGAGEMENT TIME AND
COMPONENT RELIABILITY.
SYMPTOMS: NO FRONT DRIVE AXLE ENGAGEMENT WHEN SHIFTED INTO 4X4.
Obtain the following GM part numbers:
(1) 26060073 Actuator
(1) 88959465 Harness/Spacer Kit
Read more at
http://gmcowners.com/gmc-forum/showthread.php?t=8480&kcplink=1
