denn1999

i have a 99 chevy silverado push button z71 tryed everything ive seen on here it will not engage 2wd hi it runs like its in nurtual it will do 4hi 4lo but not 2hi or auto 4wd it switchs like its going in 2hi but it wont go into gear any help on this it is driving me crazy...checked all fuses good looked at wiring it was fine no broke or loose .and is there any way to disengage the 4 hi so it will work as 2hi?

ToooTall1

Could be the dash switch or transfer case motor. Had similiar problem on my 01 silverado, first I cleaned the major ground under drivers door on frame looking forward Helped a little but decided to replace dash switch, no help finally replaced T/C motor and all is good. I would clean all connectors before buying any parts. You need to disconnect front drive shaft and forward axle connector to stop power to front drive. Good Luck

denn1999

thanks i will try that and post back ,i did buy a new dash switch still same problem,

bluemonstr

Actually your problem sounds JUST like mine. I just purchased a Encoder Motor Sensor from GM yesterday ($105) total. It's a part that is inside the Encoder Motor. I did some research on an avalanche forum and a guy had the EXACT same issue as me (while driving his truck slipped into neutral and he pretty much lost 2hi). My truck runs great in Auto 4wd or 4x4 but will NOT hold a drive gear in 2hi or 4l.

Good luck on fixing your issue...I hope my input helps. I plan on replacing this Encoder Sensor on my truck (2005 Silverado Z71) today. I will report back my 'results'. I'm HOPING this fixes the issue.

Not sure if I can post this - but I will try...

http://www.chevyavalanchefanclub.com...c,98457.0.html

bluemonstr

I changed my encoder sensor today and ALL IS FIXED. I did not need to change the whole motor. The 4x4 features are all back to working the way they should and the truck is running great.

I went from being told that my transfer case needed to be rebuild ($600 for PARTS ALONE) to thinking I needed to change the Encoder MOTOR. Finally after finding the thread on the avalanche forum I bought a new encoder sensor for $98 + tax and took my motor out and replaced the sensor...it took a couple hours (simply because putting the Encoder motor back in is TRICKY)...that took me about 45 minutes alone. lol

Good luck!

denn1999

thats it!!! that's what my truck is doing, for now i took off my shaft forward axle connector to stop power to front drive until i get my refund,my question is there a way to check if the part is bad?i've been waiting for and searching all over for some one with the same trouble i am having thanks for your help!!!...man i love this place chevy fourm rocks!!!!!

bluemonstr

Hey Denn1999 I do not know of any way to check this part w/out taking it out of your truck. From what the other threads say you need to take the sensor apart to see how messed up it is. I didn't even bother. I did the step by step replacement on my existing encoder motor and when I FINALLY got the motor back into the transfer case I hooked up the electrical w/out messing with the drive shaft and verified that it worked...I was so happy the moment it worked. I took my lunch break and ate. Then I finished the job. If the sensor didn't fix my problem at that point I was ready to go down and buy a new encoder motor. I think mechanics are willing to do the 'blanket' fix and just replace the part in total (encoder motor) without even bothering on the sensor (since it's a little extra time to mess with. They just say the motor is out and you need to replace it (and when you do that you have replaced the sensor as well). If you are having the same issues (truck drops out of gear while driving in 2hi and you cannot shift into 4L)...I would say with a lot of confidence that your issue is the sensor.

For me the trickiest part was actually putting the encoder motor back on. That took me about 45 minutes.

ToooTall1

When buying a rebuilt or new part stay away from the chinese crap as I went thru 2 of them before going to a USA remanufactured part ( A1 Cardone) from partsgeek.com. The T/C motor worked perfectly. It sometimes better to buy the complete T/C motor than just the servo unless your a mechanic as it is completely checked out and serviced as new. Just a thought, enjoy your truck as I have 2 (1999 & 2001 Silverado's both 4x4).

denn1999

here is an update,today i was going to pay bills my selector switch still showed i was in 4hi i seen a video on youtube where a guy posted his truck not going in to 4lo one was doing it when the truck was warm it did like mine use to light would blink the noise then going back to 4 hi then the other video he done it why the truck was cold went right in...well i removed my front drive shaft didnt drive all day yesterday got in today pushed 2hi went right in put it in park the truck started to roll in park huh..??
well guess it didnt work so put back in nutral pushed 4hi heard a loud tunk then light went back to 2hi put back in park then rev. it worked it is now in 2hi again wired huh? its like it knew the 4wd shaft was missing and went to 2hi, before all this started i could not go to 4lo then after our first big snow it went to 4lo and couldnt get it out then got out of 4lo got 4 hi but no 2hi would not engage now i can only get 2hi now weird...but i love my truck its right out side....lol just thought i woul post incase any one eles runs into this problem still going to get the encoder motor thanks for all the help guys keep posting back