Question about GMC Cars & Trucks

Open Question

2006 gmc 4x4 problems blows trec fuse

Replaced encoder motor, transfere case in neutral and will not shift at all blows TREC fuse when you try to shift it with switch in dash

Posted by on

6 Suggested Answers

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

  • 180 Answers

SOURCE: Chevy Tahoe stuck in neutral

Transfer case

Posted on Jan 07, 2009

  • 2 Answers

SOURCE: 1996 S10 4x4 4x4 does not engage manual shift for transfer case

I figured I'd write a followup in case it helps somebody else.

Per @ccn7's information I did some troubleshooting and determined that the problem was the thermal linear actuator (TLA) [GM# 26013495). I ordered an aftermarket replacement (600-100) from cheaper than I could get wholesale from a parts store.

It worked except that I had to remove the electrical connector from the new unit and attach the connector from the old unit. Apparently the one I ordered is for trucks manufactured before 01-02-1996. Instead, I should have ordered the newer design (600-101) and my connector would have fit. (Or so I'm lead to believe.)

I've also discovered that you can get a replacement kit that eliminates the TLA altogether. It's more expensive and more work to install, but apparently it provides additional benefits over the standard TLA. Google Posi-lok if you're interested.

Thanks for stearing me in the right direction ccn7!

Posted on Jan 21, 2009

  • 195 Answers

SOURCE: 4x4 not working

Have you checked the front axle shift solenoid? I have seen these break and have seen the fork shear as well.Make sure it is engaging when you push the button.
RPM Northwest

Posted on Jan 22, 2009

  • 443 Answers

SOURCE: 94 Sonoma 4x4 won;t lock into 4WD.

yea its not shifting again like before ? sounds like your transfer case solonoid has possably gone bad again .. these are a sometimes dont work item .. It is what shifts the transfer case into gear and it might be a little worn or weathered and not letting the switch kick it in gear all the way from the N position. thanks Jerry holler if you need more.

Posted on Feb 05, 2009

  • 124 Answers

SOURCE: where is the 4x4 encoder motor sensor located on my 03 sierra

the encoder motor sensor is inside the encoder motor. the encoder is located at the transfer case. Remove the encoder and by part number 88962315 this is the sensor. you will have to retime the motor after
hope this helps

Posted on May 06, 2009

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

Transfcase motor not shifting

Have you had it check for DTC's - diagnostic trouble codes . frustrating because you don't know what your doing. Rookies ! I'd tell you have to test but you don't have tool or knowledge .
What transfer case does your tahoe have ?
Do you know what DTC'S are ? Your vehicle 4X4 can set a bunch .

DTC B0770
DTC B0775
DTC B0780
DTC B0785
DTC B0790
DTC B2725
DTC C0300
DTC C0305
DTC C0306
DTC C0321
DTC C0326
DTC C0327
DTC C0359
DTC C0374
DTC C0378
DTC C0379
DTC C0550
DTC C0558

DTC B0775 Four Wheel Drive High Range (4HI) Indicator Circuit Malfunction

DTC B0780 Four Wheel Drive Low Range (4LO) Indicator Circuit Malfunction
DTC B0785 Two Wheel Drive High Range (2HI) Indicator Circuit Malfunction
DTC B0790 Transfer Case Neutral Indicator Circuit Malfunction

DTC B2725 ATC Mode Switch Circuit Malfunction

DTC C0300 Rear Speed Sensor Malfunction
DTC C0305 Front Speed Sensor Malfunction
Just show a few DTC'S and for everyone of these DTC'S is a diagnostic flow chart . Do you know what that is ? It's fustrating and hard to fix something when you don't have a clue as to what your doing . Do you know how to do basic automotive electrical testing ?

This would sound about what the problem could be , but with out testing id be guessing just like you .

DTC C0306 05: Motor A or B Circuit Short to Battery or Open
DTC C0306 02: Motor A or B Circuit Short to Ground
DTC C0321 01: Transfer Case Lock Short to Battery
DTC C0321 06: Transfer Case Lock Short to Ground or Open

Do yourself a favor and save some aggravation an take it to a qualified repair shop . You do know a computer controls the 4X4 system ? transfer case shift control module .

Feb 18, 2017 | 2007 Chevrolet Chevrolet Tahoe LTZ

2 Answers

04' GMC Sierra quadrasteer, trec fuse 30a blows when trying to engage 4wd. I replace fuse, start truck and 4wd auto is lit up but if I press 2h, 4h, or 4 low it blows. What should I do or look for?

Wild guess here, had a similar problem on my 2000 4x4 blazer, has an electric motor on transfure case to swith it into 2h, 4h, and 4l, would blow the fuse every time when switching, did is to replace the motor. Just confirm your fuse that is blowing feeds that.

Oct 21, 2016 | 2004 GMC Sierra

1 Answer

My 2005 chevrolet truck cranks but will not start occassionally

Here are some of the issues/repairs that may correct your issue.
-TCCM reflash
-TCCM replacement
-4wd button replacement
-Cold weather= ice, snow, slush on wheel speed sensors
-30amp TREC Fuse (unplug for 30 seconds)
-Encoder motor
-Encoder motor sensor
-ATC Fuse 20 amp fuse ( replace with 25 amp fuse)
-Replace Circuit 1640 (18 guage orange wire) with (16 guage orange wire)
-Driver side cab mount frame ( check for lose or corroded ground wires)
-Ground wires behind power steering pump on engine block ( check for corrosion or loseness)

Sep 14, 2014 | Chevrolet Chevy Cars & Trucks

2 Answers

2004 gmc sierra some times will not shift in or out of 2x2 or 4x4 some times it wont even show you what gear you are in. if you turn engine off it will reset and work then go back to not doing nothing. i...

first check is to inspect the wiring harnesses at the transfer case disconnecting all connectors on the transfer case and the connector to the transfer case shift motor and to inspect for water intrusion and corrision...You may also have a faulty actuator on the transfer case or faulty sensor in the actuator on the transfer case that can cause this problem
Good luck, i hope this helps.

Jul 22, 2011 | GMC Sierra 1500 Cars & Trucks

2 Answers

Have a gmc 2005 sierra the 4x4 doesn't work. when I press the 4x4 button blinks a few times,and then makes like grinding sounds,it sounds that is coming from transfer case,but never engage and ligth goes...

Not good! there is a sensor in your transfer case that senses that you are now in four wheel drive if your transfer case does not lock in it will set a code and the light will flash and default back to two wheel drive. check the fluid level in the transfer case and front differential for a sign of internal failure. that is causing the grinding sound.

Feb 05, 2011 | 2005 GMC Sierra

1 Answer

The TREC fuse keeps blowing every time I try to use the four wheel drive. What's wrong with it?

I have the same exact problem encoder motor is new and so is the switch any other input?

Nov 01, 2010 | 2005 Chevrolet Silverado 1500HD

1 Answer

4 Wheel drive not functional

There is a TSB on this problem: TSB #03-04-21-001C

Subject:4WD Switch Indicator Lights Flashing, 4WD Inoperative, DTCs C0327, P0500, P0836, P1875 Set (Replace Encoder Motor Sensor, Reprogram TCCM, Inspect Front Drive Axle Engagement Sleeve for Damage/Repair) #03-04-21-001D - (12/04/2003)

Models:2003 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2003 GMC Sierra, Yukon, Yukon XL
with 4WD and Electric Shift or Active Transfer Case (RPO NP1 or NP8)
You can also try removing the TREC fuse (engine fuse box) and reinstall after 30 seconds. Look up the TSB number I gave you and you'll find alot more information.

Dec 16, 2009 | 2003 Chevrolet Tahoe

1 Answer

Denali slips in and out of 4x4

How may buttons for the 4X4 two , three , or four ? Do the lights flash ? Any messages - service four wheel drive system ? Which transfer case does it have ?

Transfer Case - NVG 246-NP8 (Two Speed Automatic)
The transfer case shift control module uses the VIN information for calculations that are required for the different calibrations used based on axle ratio, transmission, tire size, and engine. The system does not know which calibration to use without this information.
Transfer Case Encoder Motor
The transfer case encoder motor consists of a permanent magnet (PM) DC motor and gear reduction assembly. It is located on the left hand side (drivers side) of the transfer case. When activated it turns the sector shaft of the transfer case (clockwise or counter clockwise) to shift the transfer case. The encoder motor is controlled with a pulse width modulated (PWM) circuit within the transfer case shift control module. This circuit consists of a driver on both the Motor Feed A and Motor Feed B circuits. The encoder motor is bi-directional to allow the motor to shift the transfer case from 2HI or 4HI to NEUTRAL and 4LO positions.
Transfer Case Encoder
The encoder is mounted to the transfer case encoder motor assembly and is replaced as an assembly. The encoder converts the sector shaft position (representing a mode or range) into electrical signals inputs to the transfer case shift control module. The module can detect what position the transfer case is in by monitoring the 4 encoder channels (P, A, B, and C). These inputs translates into AUTO 4WD, 2H, 4H, NEUTRAL, and 4L or in transition between gears.
Transfer Case Motor Lock
The transfer case motor lock is used to provide a 2H, 4H, and 4L lock-up feature. When the lock circuit is energized, the transfer case encoder motor is allowed to turn. When the transfer case is placed 2H, 4H, or 4L the motor lock circuit has no power provided to it and the lock is applied. This assures that the transfer case remains in the current gear position. When AUTO 4WD is selected the motor lock remains applied until an adaptive mode (torque is applied to the front propshaft) is required. During an adaptive mode the motor lock circuit is energized and the motor lock is released, enabling the encoder motor to turn and apply torque to the front propshaft.

SERVICE indicator (4WD/AWD) Lamp
The SERVICE indicator (4WD/AWD) lamp is an integral part of the cluster and cannot be serviced separately. This lamp is used to inform the driver of the vehicle of malfunctions within the automatic transfer case (ATC) system. The SERVICE indicator (4WD/AWD) lamp is controlled by the transfer case shift control module via a Class 2 message or by a Sevice Indicator Control Circuit.

The first thing to do before assuming it's a loose wire would be to have it checked for codes , auto zone , advance etc... can not check this codes .
DTC B0768 Service Indicator Circuit High
DTC B2725 ATC Mode Switch Circuit Malfunction
DTC C0300 Rear Speed Sensor Malfunction
DTC C0305 Front Speed Sensor Malfunction
DTC C0308 Motor A/B Circuit Low
DTC C0309 Motor A/B Circuit High
DTC C0310 Motor A/B Circuit Open
DTC C0315 Motor Ground Circuit Open
DTC C0323 T-Case Lock Circuit Low
DTC C0324 T-Case Lock Circuit High
DTC C0327 Encoder Circuit Malfunction
DTC C0357 Park Switch Circuit High
DTC C0362 4LO Discrete Output Circuit High
DTC C0367 Front Axle Control Circuit High
DTC C0374 General System Malfunction
DTC C0376 Front/Rear Shaft Speed Mismatch
DTC C0387 Unable to Perform Shift
DTC C0550 ECU Malfunction
DTC C0611 VIN Information Error

If you know nothing about this , your best bet would be to take it to a qualified repair shop .

Apr 29, 2017 | 2000 GMC Denali

2 Answers

I have a 97 chevy tahoe and the 4x4 wont lock in i just replaced the actuator and it just blinks on 4x4 . i do have 12 volts @ the harness to????

Your transfer case could be locked up. Try pulling the shifter motor (servo) off of the transfer case and manually shifting the vehicle into 4x4. Make sure to block the wheels as it will roll if you shift into neutral. If you cant shift it, you need to have a professional look at the insides of your transfer case.

Dec 22, 2008 | 1997 GMC Jimmy

1 Answer

1996 Yukon 4X4 Electronic Shift on Fly.

I had the same problem with the shift on the fly push-button 4x4 on my 97 Suburban. GM Shop manual indicates that it could be due to an encoder error on the actuator motor. Try pulling the transfer case fuse to reset the transfer case control module. Wait at least one minute. Re-install fuse then re-try operation. Did it last week and that saved me a trip to the dealership and extensive troubleshooting.

Nov 15, 2008 | 1999 GMC Sierra

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

91 people viewed this question

Ask a Question

Usually answered in minutes!

Top GMC Experts


Level 3 Expert

74896 Answers


Level 3 Expert

1311 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22095 Answers

Are you a GMC Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides