4wheel drive will not engage, encoder?

I always check to see if there is power to the actuator. If there is, then the actuator is most likely bad. If there is no power, then you need to check the relay, switch... to see where power is lost.

dose'nt switch from 2 wheel to 4 wheel, diagnosed at GM 4x4 controler still the same, no binding at selecter on tranfercase/ no power to encoder, need wireing diagram

check to make sure you are getting power at the axle. :If they are saying it's the encoder motor it very well may be. this guide will help you check the connections with the transfer case wiring diagrams below.

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

My truck blows the ATC fuse as soon as you put it in. I unhooked the Transfer case motor and the fuse did not blow. hooked it back up and blam blew. Ran a scan. with c0323 low voltage or smthn and a g1038 not sure what that one is. Do I need to replace the transfer case shift motor? Or the dash selector switch? Or look 4 smthn else?

They had more problems with the transfer case motor than the switches. If you unplugged the motor and all was good, I would start there, motors are much more likely to short than a switch, at least enough to blow fuses

Replaced Transfer case motor, stopped blowing the atc fuse, but now it will not come out of 4hi. Pull atc fuse and the front actuator will disengage the front, put it back in an the acuator engages the front. When you push the 2hi actuator and motor sound like there trying to engage but light blinks and goes back to 4hi. Removed Transfer case motor and could shift transfer case manually. Did I get a bad transfer case motor or is there something else to look for?

You may have gotten a bad one. They also had some problems with the front actuator, but I dont think that would make it stay in 4wd. Check the switch too, when the motor was shorted, it could have hurt it with too much amperage draw

Put on another new TCM and a switch. will shift from 4hi to 4lo to auto but still no 2high. im trying to get a wiring diagram to look for some grounds maybe. Im puzzled.

These had issue with the encoder motor causing this,

The wiring diagrams and instructions to change the encoder motor are attached below

Back again. Still stuck in 4hi. The control module behind the selctor switch in the dash. Do you know the part number or is it called anything besides control module and where can I buy one?

Automatic transfer case control module is what it is called. It is located behind the dash left side above headlight switch.Have you had it scanned to see if it is the problem? a trans shop should be able to do that

Yes we have scanned it and the dtc is c0323 the transfer case lock circuit low. I used the manual from the site u gave me and went through the ten step process it advised for that code and the only step we havn't done is replace that module. as step 9 recomends. How costly is this module and can i get it online? any idea of part number? Are talking about a scan or a flash something gm has to do?

Looks like it may be around $350 . Mitchell doesnt say anyhting about programming it.Probably doesnt need it, it is an off on kind of part not like a PCM. Should be plug-n-play

Hi, my 99 Suburban also blows transfer case fuse. Unplugging the 4 wire plug on the transfer case prevents fuse from blowing. I can leave 2 wire plug in TC and plug in front differential in place. Does this mean transfer case motor or less likely bad wire in harness?

9 times out of 10 it is the encoder motor that needs to be changed here are diagrams below to help you with the repair. Check out the diagrams (below). Please let us know what happens.

Ken, the motor worked like a charm I plugged it in before taking down the old one and no blown fuse, confirming it wasn't a wiring harness issue causing short. Other than figuring out the stupid clamp on the rear boot, and how to get the boot off, it was a piece of cake. Easily less than an hour job. Fortunately the female on the motor was in the same position as the male shaft on the TC, I'm not sure how I would have gotten them to line up otherwise. Power the motor or spin the rear wheels??

Yep either would have worked, glad you got it fixed. Use 2CarPros anytime, we are here to help. Please tell a friend.

I lost my 4WD. I tried to engage the 4WD by pushing the buttons on the 4WD switch. The lights on the switch would not light and the veh would not change from 2WD to 4WD. The service 4WD light came on in the instrument panel. I removed the battery cable to see if it would reset the code, the service 4WD lightwent out but there still appeares to be no power to the switch. I have replaced the actuator and the 4WD switch but I still appear to have no power to the switch. As stated above I can not engage the 4WD. Do you have any idea of the problem. Thanks

Turn the key to run and go to the front axle actuator, located on the front differential. Unplug it and test the brown wire for 12 volts. This is the same circuit as the 4wd switch. If there is no voltage then you probably have a blown fuse -- I believe it is fuse number 24 under the dash - 25amp...

Hi. I have a z71 silverado with autotrac 4wd. I was driving in 4 hi when the trucked skidded to a halt. In 2wd the truck drives great. When I try to use 4wd, any auto hi or low the front wheels are locked up and the rear will do a burnout. Any ideas on what might be happening? I'm suspecting the encoder motor on the transfer case. Thanks

There could be a problem with the front differential. Put the front wheels in the air and try to turn them in 2wd or 4wd. Check the fluid for metal shavings too.

I own a 2000 Silverado Ext. cab, with 125,000 miles, 5.3L V8. my problem is that the actuator on my transfer case is engaged, even while in 2wd, however the actuator on my front axel is disengaded and works fine. so while i drive down the interstate, the drive shaft from the transfer case to the front axel is spinning, but no power is being put to the front wheels (i did a lot of toying around to make sure that no power was going to them) so im not doing any serious damage to my truck. my question is what would cause the shifter on the transfer case stay engaged? would this problem be caused by a malfunction of the electronic shifter on the dashboard? and what are some test that i can do to try to narrow down my possible solutions? thanks a lot for the answers.

I don't actually have an answer. I have a '99 silverado 1500 Z71 stepside. i am having the same isssues. i was just wondering if you found anything out? Any help would be appreciated.. and if i find anything out i will look u up..

no i havent fixed the issue yet, but i am going to do some electrical tests to see if the electronic switch on the dashboard is misfunctioning. i have heard that these go bad frequently, so ill give that a shot sometime.

if it is the switch in the dashboard.. the truck will deffinatly let u know.. A. all the lights go off on the switch. B. message center will say SERVICE 4WD. but it is an easy fix.

Mechanic question... I have a 1999 Silverado 1500 crew cab, good motor... But this 4wd is driving me nuts! I replaced bad dash switch and actuator... I can hear actuator when i push button trying to lock the hubs in, but gives up after third try...and whole dssh switch kicks off and SERVICE 4WD LIGHT comes on in message box Sounds like its half in and half not...until I push button 2wd three times, then its out of 4wd...next time I start truck, the 4HI Light is on everytime. Then I have to go through the same ritual all over again...which I know is hard on the actuator. Anyone have an idea what might be keeping front hubs from locking in? I definitely have power from switch to actuator, then nothing. Thank you for your help!

have it scanned for codes first as it can be a body module problem as well as a connection problem and or the transfer case module. a pro will problably have to do it due to the body module as auto parts can't get those codses

4wd hi button only blinks, keeps blinking, wont go into 4wd. I can hear motor when i press button but front wheels dont engage. Instaled a new USED actuator same result. Is there a way to tell if this a tccm problem, fuse I dont know of (checked #24 4x4), transfer case , switch etc. ?

Ok we are going to pull codes to see what the codes may be present so we can see what it say's may be wrong with it. So the data link connector (DLC) is near the right side of the steering column. Now you need to make a jumper wire to go from the orange wire or term. number 13 at the DLC and ground. NOw turn key on engine off and watch the 4x4 light on the switch as it will flash codes to you. Now it will flash like a 1 pause 3 seconds and flash like a 3 meaning a 1 and a 3 as all transfer case DTC are single digit. So if you look at the diagram below it shows how it pauses as an example ok. After writing down all codes you will need to turn off the key and pull the 4x4 fuse and now turn the key on engine off 5 times this will clear all the codes from memory. Now if you look at the graph below it shows what a code 2 will look like and what a code 1 and 3 will look like ok. Let me know what you find.

OK. Used jumper to connect 13 to 5 (ground?). 2hi light went off when I did so. Turned key off. No code at all.

Ok did you do the reset procedure? If not do that just to see if it resets things. If nothing changes then we will have to test the stuff one item at a time. Now we need to check voltages at TCCM harness (transfer case control module). With key on engine off you need to check for power at the following terminals. Refer to the diagram below ok. C8, C11, C12, C14, D14 and D15. Then check for resistance at C10 to ground it should be 2 ohms or less. If all it good then you will need to pull the 4x4 selector switch out and check for voltage at the pink wire at the switch. If all this is good then we will move to the next step. The diagram below will be needed for that too. Thanks and get back to me.

I did the reset procedure, I got the 2hi button to blink a code one, with a barely visible light. not sure if that counts. Also I do not know where the tccm is or what it looks like. So far Ive found a metal box near the steering column 4"x 4"x 2" approximately.

It is under the dash on the steering column support bracket. If this checks out then we will check the transfer case relay. Let me know what you find ok. Thanks.

I got a 1996 k1500 with the push botton 4 wheel drive. The front axle actuator has 3 wires. A black ground, a brown wire with ignition power, and a light blue wire thats hot when the 4x4 button is pushed. I tested all 3 wires with a DVOM and the brown wire only has around 3 to 4 volts. I can only find wiring diagrams for the 2 wire actuator. Do you have a diagram i could see? Or any info?

if it is ignition power, then you need to start by checking fuses with a test light. otherwise, look closely at the harness for breaks.

Roy

Thats what i want to do. I see on some forums people will post wiring diagrams if someone needs them. Can you do that?

I am having trouble with my 4 wheel drive engaging the transfer case engages and the front drive shaft spins but the front wheels don't move. I replaced the actuator and checked for power and all is fine. does this mean there is something broke in the front axle?
any help would be appreciated. Thanks

Hi CFerraro,
Just having power at the plug may not be good enough. There is also a ground side to the circuit that has to be good. It's still most likely that the actuator is not engaging the differential. That is what connects the drive shaft rotation into power at the wheels. Did you replace it with a new one or used? Also, do an ohms test or use a test light to be sure the ground is good in that circuit also. let me know what you find out.
DWB

I've already bought 3 4x4 actuators, it's not a wireing issue, and the most recents one that broke the tip was broken, also I have oversized 35 tires if that has anything to do with it

Hello,

I don't show an electric actuator for your year truck?...Are you installing GM parts?, many cheaper units will fail prematurely, the over size tires shouldn't cause the actuator to fail. When you remove the actuator can you inspect inside the transfer case to see if something is causing the problem, I have seen where the engagement fork will break causing the actuator to fail, the transfer case will need to be disassembled and repaired to fix the problem.

Let us know what you find

Best, Ken