4X4 will not engage?

TCOON1998

MEMBER
1995 GMC YUKON
5.7L
V8
4WD
AUTOMATIC
107,000 MILES

I have the vehicle listed above with the 4x4 stick on the floor and when I try to shift it into 4x4 nothing happens; no dash lights or anything. Can someone please help me with this? I’ve only had the truck about 2 weeks.

Monday, March 24th, 2025 AT 9:20 AM

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
50,264 POSTS

Hello,

The first thing you need to do is check the fuses: illum, and 4WD in the fuse panel under the dash.

This guide can help you:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Here are the fuse locations and the 4wd wiring diagrams which should help as well. Check out the images (below). Let us know what you find.

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Tuesday, March 25th, 2025 AT 2:50 PM

TCOON1998

MEMBER
3 POSTS

I’ve checked all the fuses and they’re all good so what’s next?

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Tuesday, March 25th, 2025 AT 3:31 PM

KEN L

MASTER CERTIFIED MECHANIC
50,264 POSTS

Most of the time it will be the front axle actuator, but I would use a test light and check the lt-blu wire for power when the system is on.

Here is a guide to help:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Here is the location of the actuator so you can check it out, if it is getting power check the ground as well and if good replace the actuator. Check out the images (below).

Image (Click to make bigger)