1993 K1500 4 wheel drive not engaging. What is the switch on the transfer case that might be causing this? Would this switch keep the driveshaft from spinning as well?
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
Testimonial: "Mr. Molson, sorry this Thank You is way overdue, I have checked / replaced the actuator & it does work. Thks. 4 the part #'s too!"
Thanks for the info, actuator seems to work OK, I tried to manually push in the shift fork to see if the front diff would kick in but no luck. I could feel the rod I was using "pulsing" but nothing was locking in. Can you suggest parts I would most likely need to replace once I crack this thing open and pray I don't make a bad situation worse.
Thanks again
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If pushing in manualy u need the trans case in neutral and spin a front tire it will spin the diff and catch u can bust the plastic push rod and thread a bolt and make a temp fix but thus requires a Lil bit of quick fab work
Check your 4x4 fuse in the fuse panel thats what was wrong with mine hahaha easy fix but for some reason not the first thing to cross my mind
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