Hi. This is my first post in this forum, I'm hoping to get some insightful feedback. I bought a 95 Jimmy SLS back in late November and in the last couple of months, my 4 hi stopped working. I'm not sure exactly what it could be, but I know it's not the TCCM because I have changed that. Also, because the 4 lo works, I would assume it's not a vacuum line although I could be wrong. This is my first 4x4 and I really don't know a whole lot about how they work. When I'm in 2 hi and hit the 4 hi button, nothing at all happens. If I'm in neutral and switch to 4 lo from 2 hi, both 4x4 buttons will blink, then it will switch to 4 low. At this point, both 4x4 buttons may be lit up or nothing will be lit up. In either case, the truck is in 4 lo. I can switch back to 2 hi with no problems. Is this the encoder motor or is it something internal with the transfer case itself. I've had a couple of mechanics look at it and they seemed to be stumped as well. Thanks in advance for the feedback.

 

Welcome!

Test the switch first. Schematics have been posted in a number of other threads relating to the NV233 (or NP233) transfer case. The 3-button switch has regular open/close functionality to the push buttons. When you push a button, it closes a circuit telling the TCCM to shift.

 

that was one of the first things i've checked, and actually replaced it anyways because the one that was in there kinda sucked. the new one gives me the same problem. i'm pretty sure that it's not a vacuum line because it does work intermittently after i disconnect the power from the truck. i've replaced the TCCM, so unless the new one is shot too, that shouldn't be the problem. i'm thinking the problem is either the encoder motor or possibly the transfer case. if it's the transfer case, i will consider my jimmy to be a 2 wheel drive from here on out. i really don't want to put that kind of money into it. encoder motors aren't that bad from rock auto and i'm sure if i search for them, i can probably find them for even cheaper.

 

It mostlikely is a fault in the encoder itself, the position sensor for the encoder motor. This is a common fault. Have you run through the OBD2 Non-Automatic Transfer Case Diagnostics thread in the Tech Article (DIY) section to read the codes from the TCCM?

 

i checked to see if there were codes in the TCCM and there weren't any...unless there's some special way to access the TCCM with a tech 2 that neither me, my mechanic, nor a tech at the dealership couldn't figure out.

 

Did you perform the simple procedure found in the thread I stated above (CLICK HERE so you do not have to go find it yourself)?? Just checking.

Another good thread to check out:
NV233 transfer case / encoding motor switch
The controls for the NV233 transfer case did not change from 1st gen to 2nd gen so this information applies.

 

thanks, i'll be checking into those in the next few days for my jimmy. i'll have time this weekend. i'll keep you updated and let you know what i find. maybe you'll have some more information for me. thanks again.

 

although i had plenty of time this weekend, the weather was crappy. it rained/snowed the whole time and it was flippin' cold. i'll try next weekend. i'm pretty sure i'm going to be doing my ball joints, uppers and lowers, next weekend so we'll have to see. maybe i'll hook it up to a tech 2 then and see what the problem is. after reading some of the symptoms, i'm thinking it's going to be a DTC2 which is some problem with the encoder motor. i'll let you know what's going on with this as the week progresses. thanks again for the help.