4WD Fails to Engage

[Black95TD]

Years ago, the Chevy dealer replaced my thermoactuator and wiring harness. Now, my 4WD fails to engage at the most inopportune times! Its working now and won't quit in my driveway where I can diagnose it. Question? Is the new electric solnoid the likely problem. The switch seems simple. NAPA had the switch for $39 and I think the actuator is around $80.

Any ideas? Replace both?

Once again - thanks to all the members who help us keep these rigs up and running!

[rjschoolcraft]

I had problems like this some time ago and found the connector at the transfer case switch would intermittently lose contact. I stuffed some aluminum foil into the holes for the pins and have had no more trouble with it since.

[Black95TD]

Thanks! I guess I'll have to go crawl around in the snow to take a look.

[BrentN]

Black95TD,
GM redesigned that actuator years ago. The thermo expansion models always had problems.

When yours was replaced, it may have been with the same design level as the original, which meant the root cause of the problem was never truly addressed.

On my 93, it failed and I just went straight to the dealer and got the newest version, I believe it was a servo like an IAC on a gas engine which is a lot more robust. No expanding thermo fluid.

I dont know about Napa's, but once I replaced mine in my 93 it never had a problem again. As to my 99, I have had no problems.

My vote is that it is the actuator. Their failure mode is definately more pronounced when you are in the cold or the snow, with the cold temperature it takes increasingly longer to make them engage. There is also a fuse that can blow. Check the Chevy Talk.com website for this failure, it is well documented.

The new actuators are not sensitive in that manner.

Brent

[rjschoolcraft]

I agree the actuator is first suspect... However, he stated that the wiring harness was replaced with the actuator, which would indicate the new stepper motor actuator was installed. I had intermittent problems after replacing the thermal actuator with the stepper...that's when I found the connector problem at the transfer case switch.

[A||X||1||Tdawg||To many Problems ||||1||This topic has been transferred to this forum: 01-03-2005, 10:48]

I HAD THE SAME PROBLEM WITH PIN CONNECTOR AT TRANSFER CASE AFTER NEW SWICTH INSTALLED ON RECENT PERCHASE OF 96 3500 , 6.5, BANKS KIT