Rear Differential Lock Actuator


Table of contents

C0388 HUMMER Possible Causes

  • Faulty Rear Differential Lock Actuator
  • Rear Differential Lock Actuator harness is open or shorted
  • Rear Differential Lock Actuator circuit poor electrical connection

How do I fix code C0388 HUMMER?

  Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.

Tech Notes

  User Submitted Video

Cost of diagnosing the C0388 HUMMER code

  The cost of diagnosing the C0388 HUMMER code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.

Possible Symptoms

  • Anti-Lock Brake System (ABS) Warning Light ON
  • Engine Light ON (or Service Engine Soon Warning Light)

C0388 HUMMER Description

  The rear differential control circuit consists of a actuator (coil) which engages and disengages the rear axle differential lock. The rear differential actuator consists of a coil assembly, and a locking assembly with springs and pins to lock the rear differential, all within the rear differential assembly.
The rear axle differential lock actuator consists of the following circuits:
– The rear differential lock control circuit, which is connected to the transfer case shift control module and supplies battery voltage.
– The rear differential lock return (ground) circuit, which is also connected to the transfer case shift control module.
Whenever the rear differential lock has been requested the transfer case shift control module provides battery voltage through the rear differential lock control circuit, and provides ground through the rear differential lock return circuit through a current limiting driver.
Whenever a rear differential lock is requested the transfer case must be in 4 LO and the vehicle speed must be below 5 km/h (3 mph) for the request to be accepted. The rear differential lock will remain locked up to 32 km/h (20 mph) after which the rear differential lock will disengage.
This DTC detects a short to ground, short-to-voltage, or an open circuit.

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