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C0378 BUICK

C0378 BUICK - Front Axle Switch Circuit Signal Invalid

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3   
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Possible causes

  • Faulty Front Axle Switch/Actuator
  • Front Axle Switch/Actuator harness is open or shorted
  • Front Axle Switch/Actuator circuit poor electrical connection

Possible symptoms

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

C0378 Buick Description

The front axle control circuit consists of an electric motor actuator which engages and disengages the front axle. The front axle actuator motor consists of a permanent magnetic motor, a worm gear controlled plunger, a front axle switch and an electronic control circuit within the actuator assembly. The axle switch signal circuit will have 12 volts when in any 4WD mode or AWD mode and 0 volts when in 2 high or neutral. The front axle actuator consists of the following circuits:

- The front axle control circuit, which is also connected to the transfer case shift control module

- The front axle switch circuit, which is also connected to the transfer case shift control module

- An ignition 3 voltage circuit

- A ground circuit

When a shift to AUTO 4WD, 4HI, or 4LO is requested, the transfer case shift control module engages the front axle by grounding the front axle control circuit through a current limiting driver. This DTC detects a short to ground, short to voltage or an open circuit on the switch signal circuit.

OBDII Code C0378 Buick - Front Axle Switch Circuit Signal Invalid - AutoCodes.com

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