Normal Operation

The active brake booster has internal solenoids that assist driver brake applications or can apply the brakes when needed if the driver loses control. The ABS module will send a Pulse Width Modulated (PWM) signal to the active brake booster that varies with the amount of force currently required to activate the solenoid.

Operating voltage for the solenoid is supplied by the ABS module along circuit CCA22 (GY/YE), the PWM  signal is provided by the ABS module along circuit VCA22 (GN/BN).

• DTC C1285 Booster Solenoid Circuit Failure - If, during normal operation or the ABS module on-demand self test, the ABS module detects an open circuit, a short to voltage or a short to ground on circuits CCA22 (GY/YE) or VCA22 (GN/BN), DTC C1285 will be set. Also, a failure of the booster solenoid will cause DTC C1285 to be set.

This pinpoint test is intended to diagnose the following: 

• Wiring, terminals or connectors
• Active brake booster
• ABS module