I have a 99 LT that has been sitting for 2 years. Have it running good now, but have intermittant 4wd problems. Occasionally the service 4wd light comes on and the 4wd panel lights don't come on. If I put the vehicle in neutral shut it off and restart, the service light goes off and the panel lights come on as they should to show me which range I am operating in. I can hear 2-3 clicks in the dash on the passenger side when it is operating as it should. These clicks happen whem I change ranges. However, the 4wd drive will not engage at any time or in any range. I am new to this vehicle, so any help would be greatly appreciated. Thanks in advance.

 

I'm having a 4wd problem too. I have a 2002 LT with 143k miles. When I push the 4-hi button, I hear the solenoid click, but the fr. Diff doesn't engage. The red light just flashes. No service 4wd idiot light. Any advice will be great! Thanks!

 

Don't know for sure on that one but you both should use the search feature of this forum because I know it's been covered a lot by other users.
Good luck!

 

Have either of you checked the fuse in the panel for the 4wd? The switches are known to be a weak point, and would act like what both of you have posted. The switch is 35 at the dealer from what I remember.

 

Thanks hillbillyinohio. Know nothing about a blazer. I'm an old corvette nut. The fuse is ok, Where is this switch located.

 

I had the same issue w/ mine after replacing the hood latch cable. There is a vacuum line that connects to the driver's side inner fender (blind), that became disconnected. It would not allow the system to work properly, and the light on the buttom would only flash.
The vacuum driven actuator for the cable that engages the front end, is located under the battery tray. Once located, it is easy to push in the shaft to determine if the cable operates properly, and if the integrity of the vacuum system is intact (you can hear air being pushed through the system).
Follow the vacuum lines, and make sure they are in good shape, and connected.

 

I'm new to the forum and this is awesome! Thank you for the great suggestions. I'll check the fuse first and try to find the pneumatic system. If those don't do it, I'll try to figure out how to search for more suggestions. Thanks again all! Happy Blazing!!!

 

johnwalt75, if you would like to follow along in this thread, you are welcomed to. However, unless you have the exact same setup as Grenkepr (that being the 4-button NV236 transfer case), some of the suggestions may not apply to your setup. If you have questions about the steps presented in this thread, please be courteous to the original thread author and create a new thread on your problem (perhaps referencing this thread).

If the 'service 4wd' light is on, that means that the TCCM has stored trouble codes that should point you in the right direction. Disconnecting the wiring and/or pulling fuses will reset the TCCM memory and loose any stored codes so getting the TCCM scanned (requires a full feature scan tool - the generic ones will not be able to access the TCCM) should be high on your priority list.

If you cannot locate someone to scan your TCCM economically, you can start at the basics and hope you find something. Have you checked the connections at the TCCM behind the passenger side kick panel and on the encoder motor attached to the transfer case?

 

johnwalt75, thanks for the info. No I haven't done any of those things. Will do so today. I'm blind as a bat on this vehicle. Got it from my daughter in law to resell. It has been sitting for quite sometime . Finally have it in good shape but this dang 4whd is killing me !

 

Thanks to hillbillyinohio and swartlkk. Problem solved.