SunlitComet
OBS Jedi-Do Good
Under and up in the dash. Left side of steering column.
99 Tahoe 4x4 help, won't come out of 4hi
- Thread starter mrmooney
- Start date
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Okay so bought a new TCCM still same thing motor turns and front actuator extends then retracts, took that back then bought a new Front actuator same deal extends then retracts. I am at a loss. I have tried everything on the 4x4 system, TCCM, front end actuator motor buttons.
Now what?
I checked for pinched wiring everything looks good.
Now what?
I checked for pinched wiring everything looks good.
SunlitComet
OBS Jedi-Do Good
Were you able to get 4 positions on the case by hand? I will look into some more info. In the meantime, here are some articles to read which can be easier than me explaining and typing it all here. http://www.rsgear.com/articles/2004_12.pdf, http://www.rsgear.com/articles/2005_09.pdf.
---------- Post added at 10:54 PM ---------- Previous post was at 10:51 PM ----------
Also, did you reset the power lines? How was the speed sensor connected incorrectly? Did you get and t-case motor back on successfully? Also, how easily did the manual shifting go?
---------- Post added at 10:54 PM ---------- Previous post was at 10:51 PM ----------
Also, did you reset the power lines? How was the speed sensor connected incorrectly? Did you get and t-case motor back on successfully? Also, how easily did the manual shifting go?
I pulled fuses and battery cable when swapping tccm, I didn't have rear speed sensor hooked up at all during test drive. From researching online I've found the 246 only has 3 shift detents motor creates the rest? I have motor off currently and no it still doesnt line up with t case. Just kinda bugging me it all worked fine before pulling and having trans rebuilt it has to be something simple I did when replacing trans and tcase.
Tcase shifts manually fine but trans has to be in neutral or it won't shift at all,
Thanks again for all the help man.
Tcase shifts manually fine but trans has to be in neutral or it won't shift at all,
Thanks again for all the help man.
SunlitComet
OBS Jedi-Do Good
neutral is required for in and out of 4lo only. Sure you did not pinch a wire between the block and bell-housing does the dash register manual selection of gears properly. You know that when the 4x4 light came you had a code. It will not however be a p based code. you have to make contact with the tccm directly withe right hardware and software. The code prefixes will either start with a b or more commonly for the 4x4 system the letter c. Is that what you were able to talk to? That light will not come and have no code attached to it.
I don't see any pinched wires going to have to througly check again, the scanner was a snap on connected to odb port not sure model number though. Manual shifting tcase buttons still say 4hi it doesn't change when shifting manually no.
I have 3 plugs that look like speed sensor's going to tcase is that normal or should I only need 2 buddy had wiring schematic and its only showing 2 not 3?
I have 3 plugs that look like speed sensor's going to tcase is that normal or should I only need 2 buddy had wiring schematic and its only showing 2 not 3?
SunlitComet
OBS Jedi-Do Good
well the gear shifting location is gathered from feedback from the motor encoder. so it would have to be the encoder or it wiring that is indicating to the tccm that it is in 4hi if actually in 2wd. if you are shifting the case manually and not moving the encoder along with then you will likely get a false indication. In your system you should have multiple connectors, as man7y as 5 I think going to the tcase:
Transfer Case: Description and Operation
NVG 236/246-NP8 (Two Speed Automatic)
Transfer Case Shift Control Module
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.
The direct battery supply line (CKT 1640) provides the power to the module and motor circuitry.
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 A and Motor 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 automatic transfer case 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, 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 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.
Transfer Case Speed Sensors
There are three speed sensors on the Automatic Transfer Case (ATC), two on the rear output shaft and one on the front output shaft. Each speed
sensor is a Permanent Magnet (PM) generator. The PM generator produces a pulsing AC voltage. The AC voltage level and number of pulses
increases as speed increases.
Vehicle Speed Sensor
One of the two on the rear output shaft is the vehicle speed sensor (VSS) input to the powertrain control module (PCM). The PCM sends this
information to the transfer case shift control module via the Class 2 Serial Data bus.
Rear Propshaft Speed Sensor
The automatic transfer case control module converts the pulsating AC voltage from the rear transfer case speed sensor to a rear propshaft speed in
RPM to be used for calculations. The rear propshaft speed can be displayed with a scan tool.
Front Propshaft Speed Sensor
The transfer case shift control module converts the pulsating AC voltage from the front transfer case speed sensor to front propshaft speed in RPM to
be used for calculations, and to monitor the difference between the front and rear sensor speed. It is also used in the AUTO (Adapt) mode of
operation to determine the amount of slip and the percent of torque to apply to the front axle. The front propshaft speed can be displayed with a scan
tool.
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 CKT 1567.
Transfer Case: Description and Operation
NVG 236/246-NP8 (Two Speed Automatic)
Transfer Case Shift Control Module
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.
The direct battery supply line (CKT 1640) provides the power to the module and motor circuitry.
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 A and Motor 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 automatic transfer case 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, 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 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.
Transfer Case Speed Sensors
There are three speed sensors on the Automatic Transfer Case (ATC), two on the rear output shaft and one on the front output shaft. Each speed
sensor is a Permanent Magnet (PM) generator. The PM generator produces a pulsing AC voltage. The AC voltage level and number of pulses
increases as speed increases.
Vehicle Speed Sensor
One of the two on the rear output shaft is the vehicle speed sensor (VSS) input to the powertrain control module (PCM). The PCM sends this
information to the transfer case shift control module via the Class 2 Serial Data bus.
Rear Propshaft Speed Sensor
The automatic transfer case control module converts the pulsating AC voltage from the rear transfer case speed sensor to a rear propshaft speed in
RPM to be used for calculations. The rear propshaft speed can be displayed with a scan tool.
Front Propshaft Speed Sensor
The transfer case shift control module converts the pulsating AC voltage from the front transfer case speed sensor to front propshaft speed in RPM to
be used for calculations, and to monitor the difference between the front and rear sensor speed. It is also used in the AUTO (Adapt) mode of
operation to determine the amount of slip and the percent of torque to apply to the front axle. The front propshaft speed can be displayed with a scan
tool.
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 CKT 1567.
Nosferatu49534
TYF Newbie
Very interesting. I just replaced my encoder motor this after noon. We thought the tcase clutches were burned up. Pulled it out and they were all good.
Ok finally had some time to check things out again.
ITs FIXED!!! turns out my buddy or I swapped the 6 wire connection going to tcase motor with the one coming from truck. We started checking wiring and we noticed at that connection the wires changed colors which we thought was kinda weird. Swapped the harness around and sure enough motor lined right back up and it works fine.
Thanks for the help everyone. I guess that harness can be plugged into more than 1 spot.
ITs FIXED!!! turns out my buddy or I swapped the 6 wire connection going to tcase motor with the one coming from truck. We started checking wiring and we noticed at that connection the wires changed colors which we thought was kinda weird. Swapped the harness around and sure enough motor lined right back up and it works fine.
Thanks for the help everyone. I guess that harness can be plugged into more than 1 spot.
