1999 Chevy Tahoe Encoder Motor

I am wondering if anybody knows how to change an encoder motor on a 1999 Chevy Tahoe with an RPO code NP8??

It will have 3 or 4 bolts attaching it to the t-case and at least 2 wire harnesses. May have to remove the lower t-case shield and the front drive shaft for access. If possible, put the t-case in neutral before you start otherwise you will have to manually shift the t-case to line up with the coupler on the new encoder-motor. There is no need to drain the t-case fluid for the job. Attaching bolt torque is 18 ft/lbs. It's not a bad job to do.

I just heard today that GM is now saying you should put them in 4x4 at least once a month and drive a short distance just so the system gets used regularly. Supposedly that is why there are so many failures.

I just heard today that GM is now saying you should put them in 4x4 at least once a month and drive a short distance just so the system gets used regularly. Supposedly that is why there are so many failures.

i have found that this tracII fluid must be replaced every 30,000mi. that very few owners do this and what i found is the fluid looses it's lubricity. this then causes componets to not move properly and cause damage to componets.....

That can't be... GM wouldn't make a bad fluid... :headshake

That can't be... GM wouldn't make a bad fluid... :headshake

i'm not saying the fluid is bad i'm saying it needs replacement every 30,000mi. but since you brought it up whenever you are the only company that supplies any product the question of can it be done better cheaper faster always comes up

Is that the replacement interval, or does it fail before they tell you to replace it? That seemed like a very short replacement interval to me, but I don't really know. I just do what the servicewriter tells me to do :)

Is that the replacement interval, or does it fail before they tell you to replace it? That seemed like a very short replacement interval to me, but I don't really know. I just do what the servicewriter tells me to do :)
i researched this on the internet and the gm mechanic i know. this is because around 30-40kmi. the transfercase output drive shaft begins to create a ka thump noise because it does not slide when vehicle is stopped and when starting out from stop does this esp. if cold out.... under warrantee at 30,000mi dealer replaced fluid for free and admitted this was necessary. i was very surprised and as he stated after driving 10mi the ka thump would be gone and now 90,000mi later and changing this 2x more times my transfercase shifts into 4x4 smoothly and in 2wd no ka thumps........this is like the transmission fluid there is no set r/r and this is where owners are questioning if it is necessary or just a waste of time and money. i found many also agree with this change interval and i just want 4x4 to work when the time comes no surprises.....

Thanks for the info! How do you get the automatic transfer case to switch into neutral...I checked the owners manual and it told me to put the car in neutral and shift the buttons. I tried this an had no luck...Wondering if anybody has an idea????

Thanks for the info! How do you get the automatic transfer case to switch into neutral...I checked the owners manual and it told me to put the car in neutral and shift the buttons. I tried this an had no luck...Wondering if anybody has an idea????

If you tried it exactly like the manual said then maybe the encoder-motor is not doing what it's commanded to do. By the way, you never said what is leading you to the replace the encoder-motor.

Thanks for the info! How do you get the automatic transfer case to switch into neutral...I checked the owners manual and it told me to put the car in neutral and shift the buttons. I tried this an had no luck...Wondering if anybody has an idea????

if this motor is bad then you will have to manually align the encoder motor to transfer case , by lining up the grooves. when you reinstall the new motor encoder. in the repair manual it did not say anything about neutral but did state that this groove alignment was required.

My 4x4 was not engaging. When I would put it into 4Hi or 4Lo, a humming sound would come from underneath the vehicle and it would partially engage. I brought it to an auto shop because my coolant was leaking and I had them check out the 4WD in the process. Well come to find out that my intake manifold gasket and waterpump were out. They charged me $1300.00 to replace this and told me my encoder motor on my 4x4 was out. They wanted to charge me an additional $900.00 to replace it. Well I had already put up alot of money on the intake gasket and I didn't want to pay for the 4WD so I found a encoder motor on the internet: brand new, made by Dorman, for $80.00. I figured I could attempt to do it for a heck of alot cheaper than 900 bucks. I have never attempted anything with my 4wd and need to find out as much as possible before i try it.

Damn, that's pricey. ~$110/hr labor?

Yea..Tell me about it, so I fugure I can try the Encoder motor and try and save some cash!!!

I received my new motor today and the directions say tha you need to replace a gasket. Is this true? Also, how do you manually turn the transfer case shaft?

I received my new motor today and the directions say tha you need to replace a gasket. Is this true? Also, how do you manually turn the transfer case shaft?

It's been 4 years since I did the one in my Sub. It seems to me that the gasket was a reusable one.

The coupler on my '98 sub was a "double D" style with the t-case as the male and the motor as the female. I'm not sure what I used to shift the t-case to match up with the motor. Once you get it apart you'll see what has to be done.

Before you manually shift the t-case make sure that the tranny is in neutral and there is absolutely no pressure on the drive line.

Well, I finally decided to put the transfer case motor in. Not that bad of job at all. (like ya said 777stickman) Had to rremove the front driveline to access the motor. Once that was removed, three bolts hold the motor in, swapped them out, and put it all back together. Took me about 1.5 hours. Saved 900 bucks by doing it myself..Thanks all for the advice.

Well, I finally decided to put the transfer case motor in. Not that bad of job at all. (like ya said 777stickman) Had to rremove the front driveline to access the motor. Once that was removed, three bolts hold the motor in, swapped them out, and put it all back together. Took me about 1.5 hours. Saved 900 bucks by doing it myself..Thanks all for the advice.

i am happy your repair was successful. but what i find interesting is that a person such as you, and your experience in this repair , zero, did this in 1.5hrs cost of part 80.oo. so the repair shop was charging 500.00/hr. these forums are robbing the auto repair shops , trying to make a fair profit! anybody feel thier pain?

I can see where you are coming from but with my expirience, I can definetely disagree. The auto shop I have been bring my car to for years charges outrageous prices for its services. The transfer case motor I purchased was only $90.00 total but they were going to charge me $750.00 for the motor plus one hour of labor for $150.00. I asked why the motor was soo expensive and he explained to me that he gets the motor for $450.00 and they mark it up 300 dollars. That is where I draw the line. Another story was that they wanted to charge me 130.00 to put in a serpatine belt. The belt was 30 bucks at the store and took me less than 5 minutes to install. If auto places didn't mark up their service 500 percent I would definetely use them but econmically, it is better for me to do it.

These are extreme examples. Here in NYS charges such as that are illegal regarding the bloated labor charges, the shops must abide by an industry wide accepted labor hour guide.

Yeah, that's just robbery. We get our parts at a huge discount because of the volume we buy. We mark up parts just slightly above retail price of a store-brand. Except we use better parts than what a lot of part stores have (bosch [except for spark plugs], standard, moog, etc.). Shops have to make money, but $150/hr and a $300 markup should be illegal (if it's not).

These are extreme examples. Here in NYS charges such as that are illegal regarding the bloated labor charges, the shops must abide by an industry wide accepted labor hour guide.

the repair shop that operated like these people mentioned here, would be out of business in NYC in a very short time, as the residents there would not tolerate that kind of excess .........also because the failure codes are harder to access many shops take advantage and on this type of repair will overcharge.... still 80.oo for a 450.oo motor that is a great deal....