K so i picked up a 97 Jimmy that the 4x4 hasn't worked for approx 5 years i come to find out.. k so i get in and try the buttons.... nothing. not even lighting up... alright lets look @ that switch and possibly replace it, pull it out and WTF? its not even connected! so i connect this switch and it lights up and everything, alright, push 4 hi - you can hear and feel it attempting to lock in place about 5+ times and it even will go so far as to move the jimmy slightly forward in its attempt to lock in. crappy :/ so i try 4 lo - same thing... any idea's where to start with this one? i've been told it might be the solenoid's @ the front but hell if i know where to even look for these.

 

Could be one or several things. Do you have the 4 button system or the 3? Mine is the 4 button & to get into 4LO the vehicle has to be in neutral & moving slowly or it will not engage. I have never tried to engage 4HI with the vehicle stationary, have always done it on the move without a problem. Whatever mode I select it always takes a second or 2 to engage - the light next to whatever you pressed will flash until the shift has taken place. If it cannot shift into the required mode it will revert to whatever you were in before. Does your "Service 4wd" light come on?
First thing i'd check is to make sure all the vacuum lines are connected & are not leaking - this is very important as the system will not function without vacuum. If you have the 4 button transfer case there will be a solenoid valve at the top of the firewall with 2 vacuum lines on it, this is used to apply vacuum to the front axle actuator when you select 4wd. The actuator is under the battery & connects via a cable to the front axle. There is a switch in the axle that tells the transfer case control module that the axle has engaged. There is also an encoder motor bolted to the transfer case which operates the mechanism inside according to what mode you have selected. I would try the simple stuff 1st like vacuum lines & actuator & see how you get on.
If you have the 3 button system things may be different - I have never had any experiance with one of those.
When my 4wd packed up it turned out to be the switch on the dashboard. The lights used to flicker & sometimes 4wd would disengage on it's own when I hit a bump. Also the "service 4wd" light used to come on for no apparent reason. I replaced the switch with a Dorman aftermarket one & have had no problems since.
Hope this makes sense & helps point you in the right direction. I am not an expert on the 4wd system on these vehicles, am just recounting the experiences i've had with mine when I had problems last year.

 

He would have the 3-button system.

Check this out:
OBD2 Non-Automatic Transfer Case Diagnostics

See what codes, if any, pop up.

Also worth checking out is the 4x4 No Worky.... Maybe this will help.... thread.

 

well seeing as its OBD II could i just not hook my scanner up and it should pop any codes right? i'll be doing this later on anyhow

New goodies today included a brand spankin new Spectra gas tank, new diff cover and gasket, 2L of 75w90 gear oil to replace whats there, new oil filter, new air filter (this was a must because the current one is sort of dirty but mostly because the PS fluid has eaten thru part of the rubber/foam gasket on it... that and well its past the 3000/5000k mark for the oil service


tomorrow i get a new pressure line for the PS system to hopefully eliminate that damned leak :/ then its on to finishing that 4x4 repair and the door window issue (likely a pooched motor cuz i replaced the switches and i doubt 3 other switch sets were pooched)

btw Dave thx for posting a reply - i just took the time to read it! some good info on it and a heads up i have the 3 button version - there's no lights on the dash except for the WIN of abs not working lol... tomorrow i'll be checking out the vacc lines on this puppy and i suspect it might be one of them or the actuator itself - it DOES however attempt to engage and even with the vehicle in neutral on a slight slope to move some it doesn't engage.

 

The OBD system does not communicate with the NV233 TCCM so no, you cannot just hook up a scanner.

BTW, please use the 'edit' option to include more information to your post rather that posting back to back. Rules are rules.

 

my apologies about that - i'll do that in future lol. ty for the info on its ability to communicate but it makes me curious how the diagnostic how to makes it communicate with you - nothing major but i'm still gonna check for pending codes in it and then i'll use that walk thru on diag'n it - ty again for posting that link as well

i did a surf thru on the 4x4 no worky thread and it contains a craptonne of good info just didn't think it covered what was going on with mine but tomorrow's another day and i'll get it figured out in the next week ish....

 

The first link I posted goes through how to check the TCCM codes and what you will be looking at. It may give you some insight into the source of the problem and is quite easy to do.

 

so i finally got around to checking the TCCM.... hooked up pin 13 to ground & waited... put it in the "run" position and BAM not a single flash or anything from the 3 button lights (they all work too) where do i go from here? pulled the jumper off and the buttons worked fine again (light and function)

 

time to bump this thread up


Replaced the transfer case switch as it was stuck open (dropped the old one from about chest height to the floor and it works again - still got rid of it lol)
4x4 Still doesn't engage.....

Checked the TCCM diag - flashes once when you turn the truck to run - same as any other time you start it so i assume no codes stored. So this leaves me with the following symptoms:

all buttons work as intended
4hi/lo both try to engage but don't - the encoder motor is deff trying, the lights inside dim quite significantly


kind of lost now what to do to fix it - i want my 4x4 but i don't want to keep tossing parts at it in hopes this or that was the right one.