Here is my problem.

I have a 2000 jimmy 4.3L 6cyl. Two weeks ago, I needed to activate my 4wheel drive HI to get up an icy hill. As soon as I pressed the push button, it activated, but the "4WD Service" light came on. After getting to the top, I tried to put it back to 2wd, but it wouldn't engage. I took it to the shop and they wanted over $900 to replace the encoder motor. I was able to find the part for $300 and decided to do it myself. I got it installed today. After disconnecting the battery, I removed the front driveshaft and then the old encoder motor. The pin in the transfer case didn't line up with the new encoder motor, so I turned the pin. I did notmove the female end in the new encoder motor. After reinstalling everything, I started the vehicle. The four button activator switch showed that it was in neutral. I let it run for about a minute. I then pressed the 2wd button. It flashed but wouldn't engage. I then tried pushing the other buttons, but none would engage. I then put the vehicle in reverse. When it didn't go into gear, I attempted to put it back in park, but it started grinding. I turned off the vehicle right away. I put it back in park and restarted the vehicle. I attempted it again and same results.

Did I do something wrong in the installation or is the new encoder bad? Please help!!

 

If the transfer case is in neutral, then you should expect the grinding when moving from any gear to park since the transmission actually is moving, unrestrained.

Have you disconnected the battery? This may allow things to return to normal especially if the encoder motor was the actual problem. If this does not cure your problems, then remove the passenger side kick panel and disconnect the TCCM. Inspect the electrical connections for corrosion. Clean/replace as necessary. A corroded TCCM connection can cause a code for the encoder to be set. This should have been the first thing the shop checked, but they were likely looking to make a quick buck off of you.

 

Thank you. I already disconnected the battery, but I'll check the TCCM next. How will I know if it needs to be replaced?

The garage told me that the encoder motor was bad and needed to be replaced first. Then, the TCCM may be bad. All total the estimate was $1700.

 

you will know if you had problems with your TCCM when you pull it out and ininspect the connections.
where it sits, connection side up on the A-pillar, it is prone to catching moisture running down into it. over time this builds up a crud deposit at the pins and BAM it gives up trying/starts arcing/fails.
use a pipe cleaner and some rubbing alcohol to break up any crud on the pins, then use a pencil eraser to scrub them clean. you can give it an optional shot of electronics safe grease for added protection, and hook em back up.

make sure you disconnect you batter before screwing with it. After its all cleaned up and hooked up, when you start the truck, push the 2hi button a few times while it goes through it's normal start up schecks.

also while the battery is disconnected, touch your power wire and ground wire (that attach to the battery terminals) together to ground out any residule charge. this can also help "re-teach" the TCCM what it should be doing...

GL

 

Thanks for the advise so far.

I checked the TCCM and it looks fine. No signs of corrosion. I used the advise of getting rid of the residual charge and then hooked everything back up.

I started the vehicle again and it shows that it is still in neutral. This time I left it in park and pressed the 2 HI button. I let it flash for awhile, but it just stays flashing. I can also hear clicking coming from the encoder motor and/or transfer case.

Am I just not waiting long enough for it to reset? Is it possible that the pin on the transfer case needs to be turned 180 degrees? If that is the case, will I ruin the encoder motor by removing it this time, since it was preset when I bought it?

I tried disconnecting the TCCM and the battery again. This time I left it off for about 20 minutes. I hooked it all back up and started the truck again. I waited a couple of minutes and checked the clicking noise. This time, instead of just sticking my head down by the side of the car, I jacked up the car, got underneath, and used a wrench as a stethoscope. The clicking actually is not coming from the encoder motor or transfer case.

I then pressed the 2 HI and waited 5+ minutes. It just kept flashing with no change. The "4WD SERVICE" light is off, though. No noise from the encoder motor or transfer case at all. I'm not sure what route the signal takes, but I'm guessing either the switch or the TCCM is bad. Am I on the right track?

 

You could try another TCCM from a junkyard truck with the same switch in the dash. You could also check the switch resistance (search for "nv236+resistance") to make sure that it isn't something simple.

Have you tried holding the 2HI switch?

 

New development! I let it sit for awhile and then went to test the resistance on the switch. I thought I would try it one more time. When I started it, I heard the TCCM clicking and the lights on the switch went out. I also heard the encoder motor whizzing. I put it in reverse and the tranny engaged this time. I turned the vehicle off. I then took it out to determine what it was in. When I started the vehicle, the switch lit up and showed it was in 4LO. Now I can't get it out of 4LO.

I'm still wondering about a previous question that I posted. Would it have made a difference to turn the pin in the transfer case 180 degrees before installing the new encoder motor?

 

DO NOT do this. You can screw up the encoder motor if you spin it. Besides, it is not as simple as it sounds.

 

Ok. Thanks. I was hoping I didn't have to pull the encoder motor back off. I tried checking the resistance on the switch. I kept getting the same reading no matter which button I pushed, so I'm going to try and replace the switch.

Thanks for the help and I will update my progress.

 

In case it doesn't work, anyone know where to buy a TCCM? I've been looking, but can't find one.