C038D on GMC
Range Actuator Position Not Learned
C038D on GMC vehicles indicates range actuator position not learned. Au7o has documented this code across 1 GMC model — most commonly on Yukon. C038D is a General Motors chassis code set by the transfer case control module (TCCM) on electronic-shift four-wheel-drive trucks and SUVs. It is an internal programming/calibration fault with no external circuit involved: the module has not stored the learned range actuator positions and clutch stack-up tolerance it needs to know where the actuator actually is. It sets automatically any time the TCCM or the range actuator/encoder motor assembly is replaced or reprogrammed without the range actuator relearn (high/low clutch reset) being performed. The driver usually gets a "Service 4WD" message and the transfer case may refuse to shift between 2HI, 4HI, and 4LO. Typical repair costs on GMC range from $150 to $700, depending on the specific model and root cause.
Common Causes of C038D
- •TCCM replaced or reprogrammed without performing the range actuator relearn procedure
- •Encoder motor / range actuator assembly replaced without a relearn
- •Relearn procedure attempted but not completed successfully with a capable scan tool
- •Failed or interrupted TCCM software update (SPS programming)
- •Damaged, bent, pushed-out, or corroded connector pins at the TCCM or encoder motor
- •Faulty encoder motor position sensor or low battery voltage preventing the learn from completing
C038D on GMC by Model
GMC Yukon(1 issue)
- Automatic 4WD Transfer Case Position Sensor / Encoder Motor Failure2007-2020
On Autotrac electronic-shift 4WD Yukons the transfer-case encoder motor and its position sensor/selector switch fail, so the module can no longer confirm the range. The dash 4WD buttons flash, the truck won't shift between 2HI/4HI/4LO or gets stuck in one range, the Service 4WD light comes on, and codes such as C038D 'Range Actuator Position Not Learned' are stored. Worn encoder-motor contacts and corroded connector pins are typical causes.
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What does C038D mean on GMC?▼
C038D stands for "Range Actuator Position Not Learned." C038D is a General Motors chassis code set by the transfer case control module (TCCM) on electronic-shift four-wheel-drive trucks and SUVs. It is an internal programming/calibration fault with no external circuit involved: the module has not stored the learned range actuator positions and clutch stack-up tolerance it needs to know where the actuator actually is. It sets automatically any time the TCCM or the range actuator/encoder motor assembly is replaced or reprogrammed without the range actuator relearn (high/low clutch reset) being performed. The driver usually gets a "Service 4WD" message and the transfer case may refuse to shift between 2HI, 4HI, and 4LO. On GMC specifically, this code is documented across 1 model.
What causes C038D on GMC vehicles?▼
Common causes on GMC: TCCM replaced or reprogrammed without performing the range actuator relearn procedure, Encoder motor / range actuator assembly replaced without a relearn, Relearn procedure attempted but not completed successfully with a capable scan tool, Failed or interrupted TCCM software update (SPS programming), Damaged, bent, pushed-out, or corroded connector pins at the TCCM or encoder motor. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix C038D on a GMC?▼
Repair costs on GMC range from $150 to $700, depending on the specific model and root cause.
Which GMC models have C038D documented?▼
Au7o has documented C038D on 1 GMC model: Yukon.