C101C:71

PINPOINT TEST 19: DTCs C101C:01 AND 71

Normal Operation

When the combustion engine is not running, the electric vacuum pump is utilized to maintain a vacuum inside the brake booster. The ABS module controls the electric vacuum pump through the use of a mechanical relay located in the battery junction box (BJB) and a solid state relay located in the auxiliary relay box. The mechanical relay provides power to the solid state relay. The solid state relay provides power to the electric vacuum pump motor. When the ignition is in the RUN position the ABS module will close the mechanical relay. After the vehicle is started (the ready indicator is illuminated) the ABS module will activate the solid state relay as necessary to maintain a vacuum inside the brake booster.When the ignition switch is in the run position, the ABS module will send an ground signal from 0413-101 pin 35, along circuit (GY/B) to the mechanical relay. The mechanical relay will close, applying battery voltage from BJB fuse 4 (40A) to the solid state relay along circuit (V). When it is necessary to build vacuum in the brake booster, the ABS module will send a ground signal from 0413-101 pin 15, along circuit (GY/V) to the solid state relay. The solid state relay will then apply the battery voltage from circuit (V) to the vacuum pump along circuit (W/G) and to the ABS module on circuit (L). The ABS module monitors the voltage available on circuit (L). If a relay circuit or electric vacuum pump circuit is shorted to ground, shorted to voltage, open or has high resistance, a DTC will set.The logic internal to the solid state relay provides circuit protection for the vacuum pump circuit (W/G). If a short to ground on circuit (W/G) is detected, the relay will stop applying power to circuit (W/G) until the short has been repaired.If a vacuum pump DTC is set the red BRAKE indicator will illuminate and the combustion engine will run to supply vacuum to the brake booster.

- DTC C101C:71 (Brake Vacuum Pump: Actuator Stuck) - if the ABS module detects that vacuum in the brake booster is increasing when the vacuum pump is commanded off and the combustion engine is not running, this DTC will set.

Possible Causes
- Fuse(s)
- Wiring, terminals or connectors
- Electric vacuum pump solid state relay
- Electric vacuum pump solid mechanical relay
- Electric vacuum pump
- ABS module

Diagnostic Procedure

CAUTION:Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

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