Hi guys...I'm new to this forum. I did some searching and found several problems related to 4x4 but none exactly like mine. Here's the details of my Blazer:
-Just picked this up for my son.
-99 LT with auto 4x4- 4 button (nv236 transfer case?)
-Odometer says 115k miles but I can tell it has a new motor...I think out of an Astro Van judging by the elongated oil dipstick.
-Runs good

When I brought the Blazer home, it started snowing pretty good. I had been driving for 45 min and thought I would put it in "auto" to see how it worked (I checked all buttons/4x4 functions when I originally test drove before purchasing...all worked fine, no svc 4wd lights, etc) but thought I would really see how it worked. It shifted into auto without any trouble but would not come out into 2hi, 4hi or 4lo. The light stayed solid and would not shift. After a minute or two, the "Service 4WD" light came on. I drove the vehicle home and parked it. The next day, I started it and after about 30 sec tried to shift it back into 2hi. It worked fine. I drove the Blazer around town without any trouble. So, I thought I would try 4x4 again but this time went to 4hi. Again it shifted without any trouble and drove it in 4hi as it was another snowy, slippery day in Michigan. After a couple of minutes, the "Service 4WD" light came on again and I couldn't shift it out of 4hi. I pulled over into a parking lot, shut off the Blazer, waited about 30 seconds and restarted. I was able to shift it back to 2hi without any trouble. I took the Blazer to a friend and had the code read. He said the code indicated a "rear output shaft sensor on the trans/ transdr case". I replaced the rear sensor (passenger side) on the back of the transfer case (there is another one on the driver side but I believe this is for the front, not rear). I still have the same issue. I can shift out of 2hi to auto, or 4hi without any issues but after a few minutes, the "Service 4WD" light comes back on. I can shut down the vehicle, restart and then shift back into 2hi without any trouble. Any thoughts?

Thanks!

Tim

 

What was the specific code that your friend pulled?

Have you checked over all of the electrical connections in the system (dash switch, TCCM, & encoder motor) for corrosion?

 

Where are the TCCM and encoder motor?

 

TCCM is behind the passenger side kick panel & the encoder motor is located on the driver side of the transfer case near the front driveshaft.

The information above and much more is only a search away.

 

I currently have a B2961 code...any idea what this is?

 

Next time, try starting your own topic. You're much more likely to get the help you need that way.

is your friend.


This diagnostic procedure supports the following DTC:

DTC B2961 Key in Ignition Circuit

Conditions for Running the DTC
The ignition is ON.

Conditions for Setting the DTC
• The ignition 1 input is active and the key in ignition switch signal circuit is inactive and the signal circuit is high.

• The above conditions must be present for more than 5 seconds.

Action Taken When the DTC Sets
The BCM stores DTC B2961 in memory.

Conditions for Clearing the DTC
• The DTC becomes history when the fault is no longer present.

• A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.

• The BCM receives the clear code command from the scan tool.

 

Thanks for the response!

 

No problem. Sorry, I didn't realize you were the OP.