Jimmy 4 Wheel transfer quit

[Starider1218]

My 1995 Jimmy would not shift into 4w hi or low the other day so after looking at some of the discussions I disconnected the battery for about an hour and now it won't come out of 4w hi. Anybody.. does it sound like a module or what? Suggestions as to the part number and a source for the part? Thanks a bunch.

[rlith]

Originally Posted by Starider1218

My 1995 Jimmy would not shift into 4w hi or low the other day so after looking at some of the discussions I disconnected the battery for about an hour and now it won't come out of 4w hi. Anybody.. does it sound like a module or what? Suggestions as to the part number and a source for the part? Thanks a bunch.

Have you checked the vac actuator under the battery for tears or holes? Have you checked all the vac hoses leading to and from the vac switch on the transfer case? Have you checked the encoder motor?

[herkyhawki]

A searchbrings up many many many threads that say to check the encoder motor, but none tell how to do this. Can anyone explain how to check an encoder motor.
If there is anyone who can write a complete description of the 4WD system it would be a very valuable "sticky thread" this time of year. When you go from 2wd to 4HI, apparently two things must engage, the transfer case and the front hubs, how do you isolate and test for each function??

[DelCoch]

Among other things with the 4x4 not working right on my '95, I sometimes have a problem with it not shifting out of 4-hi. What works for me is to stop and back up a couple feet, and it will go back into 2-wheel drive.

Keep in mind the '95 & '96 are animals of their own, as changes were made on the '97 and newer 4x4's trans.

[MT-2500]

If it is a 233 0r 243 transfer case.
Check for codes. Ground pin 13 and count them flashes and post back code.
MT

[Starider1218]

Originally Posted by rlith

Have you checked the vac actuator under the battery for tears or holes? Have you checked all the vac hoses leading to and from the vac switch on the transfer case? Have you checked the encoder motor?

Thanks for the reply, I happened to be at a customer during work that was a small GM dealer and the mechanic said just what you have said. He did also say that if I unhooked the vacuum to the switch on top of the transfer case, that the case should release and go back to 2W but that would not solve the problem. It's too darn cold here in Iowa right now to mess with it in my unheated garage. I plan on looking at it this week end. I will let you know how it goes. Thanks.