96 Suburban 4x4 won't engage...

[danxnorman]

Afternoon! Im a new member with a 96 Suburban. 4x4 won't engage. Light on 2H button stays on but light on 4H and 4L buttons flashing. I have replaced the thermo-actuator. It does go into Low range but still only rear wheels driving. What should I check next? If it's the clip on the passenger side drive shaft in the diff, that might be beyond my abilities but I'm open to suggestions... Thanks!

 

[Schurkey]

Sounds more like a transfer case problem than a differential problem, although with low-range active I may be wrong.

Do you have power and ground at the thermo-acutator? If you unscrew it from the axle, then plug the electrical connector back in, does it pop out within 30 seconds or so when the transfer case is shifted into 4WD?

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[danxnorman]

Yes, thermo-actuator working properly...

 

[Moofus02]

What transfercase? It is going into low range but not turning front drive shaft? Does the front shaft turn the front axle when the axuator engages?