Electric actuator on front axle does not engage in four wheel drive

VACERO

MEMBER
1993 GMC SIERRA
280,000 MILES

I just recently lost four wheel drive on my truck. I checked it out and adjusted linkage etc, checked wiring for breaks as best I could, found no power to electric actuator on front axle. Checked fuse, okay. The transfer case does engage when I manually select four wheel drive as the front drive shaft locks in. I am wondering if one of two sensors I see on the transfer case transfer power to the front axle when I select four wheel drive is faulty and how would I check them?

4 Replies

JACOBANDNICKOLAS

MECHANIC
109,876 POSTS

Yes, power comes from a relay. I have attached a wiring schematic for the transfer case. It should help. Let me know if you have questions. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

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Sunday, October 9th, 2011 AT 7:24 PM

BIGHSUMMERS

MEMBER
2 POSTS
1993 GMC SIERRA
220,000 MILES

My 4x4 system will engage but wont actually engage the front wheels.

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Monday, November 11th, 2019 AT 5:28 PM (Merged)

BIGHSUMMERS

MEMBER
2 POSTS

You can here the transfer case working but the front wheels still doesn't engage.

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Monday, November 11th, 2019 AT 5:28 PM (Merged)

PROTECH1980

MEMBER
901 POSTS

If the transfer case is working then the front actuator (on front axle). Check for power and ground at actuator when transfer case in 4x4, if you have power and ground but front axle doesn't engage the actuator is most likely at fault.

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Monday, November 11th, 2019 AT 5:28 PM (Merged)