Have an 08 trailblazer at startup everything is fine. Once u drive down road and hit about 30 mph or 3rd gear, service 4wd light comes on. While driving if move selector switch to auto it will blink and take while to transfer but does sometimes have to slow down to do it. Now once in auto mode if u stop and start out and make turn its in 4wd even though auto mode is still selected. I know from the binding or hop so to speak. Now at this time stabiltrak light comes on also. Once stabiltrak light comes on you can't switch out of auto mode until shut truck off if u move selector switch once in auto mode it won't do anything auto mode light just stays solid no ther lights flashing when u move to another mode like 2wd. Once you shut truck off and restart it will read in 2wd drive mode and no service 4wd light on until hit about 30mph and light will come every time. If u start vehicle and select any modes auto, 4hi, and 4lo it will make every selection and encoder and actuating motor will work as supposed when making each selection and no service 4wd drive light on until u drove and hit 30 mph. Pulled codes and have c0455 stabiltrak c0300 rear props haft or speed sensor and c0374. I'm leaning toward rear speed sensor, bad connection , encoder motor position sensor or even tccm reprogramming. I believe tsb about c0300 and c0374 and with both codes could need tccm reprogramming. I've been doing some searching and have found couple others having same issues only to se no answers to problem. My questions are can you test speed sensor to see if bad and if so what readings should I have on my multimeter and could encoder motor position sensor be possible cause. I think c0455 steering wheel position sensor is present because stabiltrak light coming on. That light only comes on when you put in auto mode and start out making a turn. Any other time your driving and 4wd service light on the stabiltrak light is not on. Sorry for long post, just trying to put as much info about problem as possible.
4wd service light on
- Thread starter Wildbillsru
- Start date
IllogicTC
Member
- Dec 30, 2013
- 3,452
DTC C0374
Circuit Description
The transfer case shift control module senses rear slip. After several attempts of applying torque to the front wheels, by activating the encoder motor, the transfer case still sees a difference in speed between the front propshaft speed sensor and rear propshaft speed sensor.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0374 General System Malfunction
Conditions for Running the DTC
The transfer case shift control module is unable to correct sensed wheel slip for 10 consecutive seconds .
Action Taken When the DTC Sets
Circuit Description
The rear propshaft speed sensor is a permanent magnet generator. The permanent magnet generator produces a pulsing AC voltage. The AC voltage level and number of pulses increase as speed increases. The module converts the pulsating AC voltage to a propshaft RPM which is used for calculations. The propshaft RPM can be displayed with a scan tool.
This DTC detects an open, short to ground, short to voltage or faulty sensor.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0300 Rear Speed Sensor Malfunction
Conditions for Running the DTC
The system logs the DTC if the rear propshaft input indicates a speed of less than 16 RPM for 30 seconds while all of the following are true:
I don't have any info on C0455, as that code was not implemented until later years. It could very well be the speed sensor (300 is specifically about the speed sensor, and 374 uses the speed sensors in order to detect slip). Let's see what others say, and welcome to the club.
Circuit Description
The transfer case shift control module senses rear slip. After several attempts of applying torque to the front wheels, by activating the encoder motor, the transfer case still sees a difference in speed between the front propshaft speed sensor and rear propshaft speed sensor.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0374 General System Malfunction
Conditions for Running the DTC
- The ignition is ON.
- System voltage is 9 - 18 volts .
The transfer case shift control module is unable to correct sensed wheel slip for 10 consecutive seconds .
Action Taken When the DTC Sets
- All shifts to Auto mode are disabled. If the current mode is Auto, the system does not allow any further adaptive events, such as correcting slip.
- The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.
Circuit Description
The rear propshaft speed sensor is a permanent magnet generator. The permanent magnet generator produces a pulsing AC voltage. The AC voltage level and number of pulses increase as speed increases. The module converts the pulsating AC voltage to a propshaft RPM which is used for calculations. The propshaft RPM can be displayed with a scan tool.
This DTC detects an open, short to ground, short to voltage or faulty sensor.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0300 Rear Speed Sensor Malfunction
Conditions for Running the DTC
- The ignition is ON.
- System voltage is 9 - 18 volts .
- Vehicle speed exceeds 16 km/h (10 mph) .
The system logs the DTC if the rear propshaft input indicates a speed of less than 16 RPM for 30 seconds while all of the following are true:
- The transmission is NOT in PARK/NEUTRAL.
- The engine is running.
- The front axle is engaged.
- Vehicle speed on Class 2 data bus exceeds 16 km/h (10 mph) .
- All shifts to AUTO or the Adapt mode, is disabled. If the current mode is AUTO, the system does not allow any further adaptive events, such as correcting slip.
- The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.
I don't have any info on C0455, as that code was not implemented until later years. It could very well be the speed sensor (300 is specifically about the speed sensor, and 374 uses the speed sensors in order to detect slip). Let's see what others say, and welcome to the club.
marinegrunt
Member
- Oct 13, 2012
- 110
I have some used speed sensors from a used transfer case I purchased. I plan on rebuilding the t case but would be more than happy to mail you one just to try if you get it back to me.
