Stuck in 4WD. Any help?

[TheEnder53]

It rained her last week pretty bad and i had my Tahoe in Auto 4WD as it lacks Traction Control.

It locked the front wheels, and then never unlocked them. I got a service 4wd light on the dash and it will not go into 2HI. It just stays in 4HI.

The lights sometimes dim themselves down to nothing and occasionally pressing the buttons does nothing. When i press it into 2hi i hear something under the vehicle that buzzes twice and then stops. Like it’s trying to engage but can’t.

Current codes are B2725 and C0324. From what i understand these are codes for both the encoder motor and the dash actuator. Any help?

 

[Big Mama]

On my Sierra it was the encoder motor. Have you tried disconnecting the battery?

 

[strutaeng]

I've never tried this myself, but I think you should be able to remove the encoder motor and rotate the splined shaft with some channel lock pliers. I've read folks have done that before.

If the encoder motor is okay, there's a little black reluctor wheel that called something like "range switch" or something like that. It's like $20. That went bad on my 04 suburban.

 

[rockola1971]

C0324 is your tattletale. This code means your lock solenoid in your encoder motor is short to ground. This solenoid is ground seeking to lock and since its shorted it is locked all the time keeping your encoder motor from shifting to a different gear in your Tcase. You can remove the encoder motor and manually shift it into 2wd and leave the encoder off until you get a new one.

 

[TheEnder53]

C0324 is your tattletale. This code means your lock solenoid in your encoder motor is short to ground. This solenoid is ground seeking to lock and since its shorted it is locked all the time keeping your encoder motor from shifting to a different gear in your Tcase. You can remove the encoder motor and manually shift it into 2wd and leave the encoder off until you get a new one.

Literally do not get any notifications for this thread or i would’ve responded sooner, lol.

Thank you. Which way should i turn it for 2HI?

 

[TheEnder53]

C0324 is your tattletale. This code means your lock solenoid in your encoder motor is short to ground. This solenoid is ground seeking to lock and since its shorted it is locked all the time keeping your encoder motor from shifting to a different gear in your Tcase. You can remove the encoder motor and manually shift it into 2wd and leave the encoder off until you get a new one.

Got new Encoder motor today.

Tried to install it. Would not like up at all no matter what position i tried to connect it with.

Thought it was because its in 4wd hi, and tried to move the switch on the TC but i don’t know where neutral is. Hooked up the motor to the truck with it off the TC and attempted to shift it, only to be met with the exact same sound and symptoms my old encoder had. Did not move out of the position it was in and set C0324 with a new motor.

What next? I am driving it in manual 2wd and will probably return the new encoder. I recently fixed the drivers side ground and this issue didn’t get bad till i cleaned that ground.

 

[rockola1971]

Got new Encoder motor today.

Tried to install it. Would not like up at all no matter what position i tried to connect it with.

Thought it was because its in 4wd hi, and tried to move the switch on the TC but i don’t know where neutral is. Hooked up the motor to the truck with it off the TC and attempted to shift it, only to be met with the exact same sound and symptoms my old encoder had. Did not move out of the position it was in and set C0324 with a new motor.

What next? I am driving it in manual 2wd and will probably return the new encoder. I recently fixed the drivers side ground and this issue didn’t get bad till i cleaned that ground.

Was the sound coming from your encoder motor or Tcase? Installation of encoder motor is hook wiring harness to it while it is OFF of the Tcase. Push Auto4wd or 2wd or 4hi and then manually put Tcase into that gear then attach encoder motor.

 

[TheEnder53]

Was the sound coming from your encoder motor or Tcase? Installation of encoder motor is hook wiring harness to it while it is OFF of the Tcase. Push Auto4wd or 2wd or 4hi and then manually put Tcase into that gear then attach encoder motor.

Sounded like it was coming from the encoder motor. 2 distinct fluorescent light type buzzing.

Encoder was off the transfer case and not installed as i couldn’t get it aligned.

 

[rockola1971]

Sounded like it was coming from the encoder motor. 2 distinct fluorescent light type buzzing.

Encoder was off the transfer case and not installed as i couldn’t get it aligned.

It is suppose to sound like a buzzing when it is engaged and rotating. You have to have your Tcase physically shifted at is shit shaft to the same gear that you commanded the encoder motor to for everything to align correctly and bolt up to the Tcase mounts. Verify that you have the correct encoder motor by its female coupler shape being the same shape as the shaft on the Tcase. There are a couple different version that arent interchangeable.

 

[TheEnder53]

It is suppose to sound like a buzzing when it is engaged and rotating. You have to have your Tcase physically shifted at is shit shaft to the same gear that you commanded the encoder motor to for everything to align correctly and bolt up to the Tcase mounts. Verify that you have the correct encoder motor by its female coupler shape being the same shape as the shaft on the Tcase. There are a couple different version that arent interchangeable.

It is the same shape. The issue is that the encoder motor makes the same sound as the old one, and doesn’t change positions when i try to select it via the dash selector, and the vehicle will only shift into 4lo/4hi with a crescent wrench.

Thing that stumps me is that both old and new encoders were at the same location of the female end of the shift shaft on the encoder. Yet I now cannot get either back on with the TC in the original position (4HI). So I am a bit stumped with that.

 

[TheEnder53]

It is the same shape. The issue is that the encoder motor makes the same sound as the old one, and doesn’t change positions when i try to select it via the dash selector, and the vehicle will only shift into 4lo/4hi with a crescent wrench.

Thing that stumps me is that both old and new encoders were at the same location of the female end of the shift shaft on the encoder. Yet I now cannot get either back on with the TC in the original position (4HI). So I am a bit stumped with that.

Forgot to mention. Selecting 4HI with the new shift motor resulted in just the same 2 buzzes and it never moved.

 

[rockola1971]

Need year and trim level so I can dig up schematic of the 4wd for your ride. What does the RPO code show for your TCASE? NP8?

 

[TheEnder53]

Need year and trim level so I can dig up schematic of the 4wd for your ride. What does the RPO code show for your TCASE? NP8?

Yes.

It is a 2001 Tahoe LS 4X4.

 

[TheEnder53]

Got the new encoder in. Cleared all fault codes, no Service 4X4 on dash anymore. Tried to shift into 2HI and it failed immediately, and threw C0324 again.

What gives?

 

[Fless]

I don't know that the values in the link below are correct for your year, but you might pull the dash switch and clean the contacts, or replace the dash switch with a new one for your model year and T/C. A good bi-directional scanner would help you see what's being commanded vs. actual.

“Service 4WD” message

2004 Tahoe Z71 w/ about 155,000 miles. I did a little digging on this forum and found a couple threads on this issue, but still had some questions. Today I got a “Service 4WD” message on my cluster display and also noticed the lights indicating 2wd, 4hi, and 4lo were not lit up. I use 4WD...

www.tahoeyukonforum.com

Are you able to freely move the transfer case shaft to the different positions with a wrench or channel-lock pliers? I assume your T/C shaft has the two flats, and not the newer "star" end.

 

[TheEnder53]

I don't know that the values in the link below are correct for your year, but you might pull the dash switch and clean the contacts, or replace the dash switch with a new one for your model year and T/C. A good bi-directional scanner would help you see what's being commanded vs. actual.

“Service 4WD” message

2004 Tahoe Z71 w/ about 155,000 miles. I did a little digging on this forum and found a couple threads on this issue, but still had some questions. Today I got a “Service 4WD” message on my cluster display and also noticed the lights indicating 2wd, 4hi, and 4lo were not lit up. I use 4WD...

www.tahoeyukonforum.com

Are you able to freely move the transfer case shaft to the different positions with a wrench or channel-lock pliers? I assume your T/C shaft has the two flats, and not the newer "star" end.

Yes, it has the 2 flats.

I can freely get it into 4hi or 4lo. I’m not sure which way i’m supposed to move it to get it into 2hi, but either way i spin it results in it not spinning anymore. Just gets stuck. I will test it out more. For right now, it drives fine without the front driveshaft.

 

[TheEnder53]

Followed the instructions on the service manual. Disconnected the TCCM & Encoder and hooked up a test light connected to ground.

Probed encoder motor lock solenoid control wire (Pin D, Connector C1) for short to voltage - did not light up. Pin D lit up, just to be sure it was getting constant voltage.

To make sure I was getting the correct reading, I probed connector E1 (Tan, Lock solenoid control) on the orange connector for the TCCM. Again showed up nothing. So that rules out wiring.

New TCCM on the way. Will be in in around 12 hours.

 

[TheEnder53]

I don't know that the values in the link below are correct for your year, but you might pull the dash switch and clean the contacts, or replace the dash switch with a new one for your model year and T/C. A good bi-directional scanner would help you see what's being commanded vs. actual.

“Service 4WD” message

2004 Tahoe Z71 w/ about 155,000 miles. I did a little digging on this forum and found a couple threads on this issue, but still had some questions. Today I got a “Service 4WD” message on my cluster display and also noticed the lights indicating 2wd, 4hi, and 4lo were not lit up. I use 4WD...

www.tahoeyukonforum.com

Are you able to freely move the transfer case shaft to the different positions with a wrench or channel-lock pliers? I assume your T/C shaft has the two flats, and not the newer "star" end.

I got the new encoder both hooked up to the TC and hooked up electrically.

New TCCM is installed as i tested wiring integrity to verify it was good.

Now, the issue is that the new TCCM is throwing code U1000. It takes a good 5 minutes from the time i turn the key to RUN for all of the lights to go out on the 4WD switch. Getting farther, but still, stuck.

It shifts beautifully between whatever gear I select after it eventually works. No issues.

 

[HardyHoe]

Correct me if any of this isn’t the case:
>you drove in auto 4WD
>couldn’t disengage & return to 2WD
>4 Hi became engaged (or at least the indicator light) after driving for a couple days in Auto 4WD?

Do you have the heat driven 4WD Actuator that locks the hubs? I’m not sure what year you said you had.

 

[Fless]

Do you have the heat driven 4WD Actuator that locks the hubs? I’m not sure what year you said you had.

He said 2001 Tahoe LS 4X4 in post #13.

@TheEnder53 what TCCM did you get? I know the later Tahoes need to have them programmed, or be purchased as not needing to be programmed. Not quite sure about yours.