Transfer Case NP246 Encoder

RickJ · July 11, 2017

I'm posting this to help others who may have the same or similar issue. i spent hours on the interweb trying to find this information and it took multiple sources to finally find the answer.

At issue was a 2005 GMC K1500 104K miles, the NP246 transfer case started acting weird in the summer of 2016, inquiries on the net led me to replacing the 4WD dash switch. After swapping the new and old switches in and out a few times the problem with the transfer case not shifting, erratic indicator lights, the TC being engaged in the wrong mode, etc. seemed to be fixed, but I didn't trust it. In May 2017 in the middle of a long road trip, the TC problem reappeared. The indicator said it was in 2WD, but there was a drag on the drive line. It remained in a HI range and the drive line did not bind on dry pavement and it cleared up rather quickly so that I could make the 1500 mi. trip home. When I was home I did more interweb searching and found many "encoder" threads on various forums. I ordered a Dorman brand encoder ring on Amazon and was in no hurry to install it, but a few days ago the drive line drag came back. Got the encoder off the truck and replaced the ring, marking the drive and driven gears to insure alignment. But it would not go back onto the TC, the shift shaft on the TC and the socket in the encoder were very slightly misaligned. I could turn the shaft slightly by hand, but not enough to align them and was cautious about using force. The blind spline on the TC shaft was at about 7 o'clock, but I did not know what mode it was in. There was a forum entry saying to use the dash switch to shift the encoder to the last known mode that the TC was in before the encoder was removed. I did this, heard the motor whir and when I looked at the socket it was at about 11 o'clock, now it's way off and I don't know how to get it closer. More searching said to get the rear wheels jack off the ground as to allow turning the driveshaft with the trans in neutral and using a pliers or vise-grips to manually shift the TC. Doing this I discovered that neutral was with the blind spline being at 6 o'clock. But I now need to get the encoder to 6 o'clock. I stumbled upon a You Tube spam video by Delco that offered the final answer, see the link. I followed those instructions to align the bull gear in the encoder by using timing marks on the gear and case that will set blind spline in the gear and the encoder ring to neutral. I hope this long winded explanation and link helps someone.

RickJ · July 11, 2017

Pics of TC and encoder clocked to neutral.

Chubbs878 · August 27, 2017

Just to be clear, how do you know which position is "neutral" on the TC input shaft (where the encoder motor attaches?)

I'm interpreting your post as:

First align the encoder motor per video instructions, i.e. Timing Mark

THEN

Adjust the TC input shaft to match the encoder ring position that was previously set up? Thanks.

RickJ · August 27, 2017

Chubbs, you verify that the TC is in neutral if the rear driveshaft turns (with the rear tires off the ground) when the transmission in in PARK.

I don't think it matters which part you align to neutral first, TC or encoder or vise-versa. Apparently in most situations the actuator mounts back onto the TC with no issues because no one online or YouTube mentions problems like I experienced.

I put this up because there is nowhere to find this info...except here.

BTW after fixing the TC successfully I traded the 2005 which I had purchased new on Dec 31, 2004 for a 2014 Silverado. I notice that you are from Dallas, my daughter and her family moved to Prosper last year and I was getting leery of driving the '05 down there three or four times a year. I had visions of a truck breakdown in OK in front of that prison on Hwy 75 north of Atoka.

Chubbs878 · August 27, 2017

Haha! You didn't want your pickup to break down in front of the prison, huh?? That's funny.

DFW is so big; you have mesquite, (where I live) Garland, Richardson, Allen, Plano, Frisco, Carrollton, Farmers Branch, Las Colinas, Irving, HEB, Arlington, (AT&T & GlobeLifePark) Oak Cliff. That's kind of working around in a circle starting East Dallas.. I left out Lewisville & Seagoville maybe a couple others. Sometimes I get on Clist Dallas & have to ask people for shipping bc they may be 30 miles away & still considered "Dallas."

I just got a 2003 Yukon 4x4 with 125k, 1-owner. Too bad the prev/own didn't do a lick of maint on it; I spend about $100-200/wk just updating your everyday maint' items. Fluids/brakes/plugs/filters.. everything on it was original LmAo.

I'm thinking here pretty soon I will be replacing something more major like a hub/CVaxle/CA/diff or Tcase. It wasn't driven hard but at the same time everything is now almost 20-years old. Costing me a ton