C1085

C1085 - VACUUM PRESSURE SENSOR CIRCUIT HIGH






For a complete wiring diagram Refer to the Wiring Information.

- When Monitored:
With the ignition on.

- Set Condition:
When the Anti-Lock Brake Module (ABM) indicates that the Vacuum Pressure Sensor Signal is out of range.






1. CHECK FOR A DTC C1085-VACUUM PRESSURE SENSOR CIRCUIT HIGH

NOTE: This DTC must be active for the results of this test to be valid.

1. Turn the ignition on.
2. With the scan tool, read and record DTCs.
3. With the scan tool, read and record Environmental data to help identify the conditions in which the DTC was set.
4. With the scan tool, erase DTCs.
5. Start the engine.

NOTE: Attempt to operate the vehicle under conditions similar to which the DTC was set. It may be necessary to test drive the vehicle within the DTC monitoring and set conditions in order for this DTC to set.

6. Depress and release the brake pedal.
7. With the scan tool, read and record DTCs.

Does the scan tool display: C1085-VACUUM PRESSURE SENSOR CIRCUIT HIGH?

Yes
- Go To 2

No
- Perform the ABS-INTERMITTENT CONDITION TEST.

2. CHECK THE TERMINALS/CONNECTORS/WIRING HARNESS FOR DAMAGE

1. Turn the ignition off.
2. Check all related wiring for bruised, chafed, pierced, or partially broken wires.
3. Check all related connectors for broken, bent, pushed out, or corroded terminals.

Were any problems found?

Yes
- Repair as necessary.
- Perform ABS VERIFICATION TEST.

No
- Go To 3

3. (B31) VACUUM PRESSURE SENSOR SUPPLY CIRCUIT






1. Disconnect the Vacuum Pressure Sensor harness connector.
2. Turn ignition on.
3. Using a voltmeter, measure the voltage of (B31) Vacuum Pressure Sensor Supply circuit at the Vacuum Pressure Sensor harness connector.

Is the voltage between 4.5 to 5.2 volts?

Yes
- Go To 6

No
- Go To 4

4. (B31) VACUUM PRESSURE SENSOR SUPPLY CIRCUIT OPEN






1. Turn ignition off.
2. Disconnect the Anti-Lock Module harness connector.
3. Measure the resistance of the (B31) Vacuum Pressure Sensor Supply circuit from the Vacuum Pressure Sensor harness connector to the Anti-Lock Brake Module harness connector.

Is the resistance below 5.0 Ohms?

Yes
- Go To 5

No
- Repair the (B31) Vacuum Pressure Sensor Supply circuit for an open.
- Perform ABS VERIFICATION TEST.

5. (B31) VACUUM PRESSURE SENSOR SUPPLY CIRCUIT SHORTED TO GROUND






1. Measure the resistance between ground and the (B31) Vacuum Pressure Sensor Supply circuit at the Vacuum Pressure Sensor harness connector.

Is the resistance below 5.0 Ohms?

Yes
- Go To 12

No
- Repair the (B31) Vacuum Pressure Sensor Supply circuit for a short to ground.
- Perform ABS VERIFICATION TEST.

6. (B33) VACUUM PRESSURE SENSOR RETURN CIRCUIT OPEN






1. Measure the resistance of the (B33) Vacuum Pressure Sensor Return circuit from the Vacuum Pressure harness connector to the Anti-Lock Brake Module harness connector.

Is the resistance below 5.0 Ohms?

Yes
- Go To 7

No
- Repair the (B33) Vacuum Pressure Sensor Return circuit for an open.
- Perform ABS VERIFICATION TEST.

7. (B32) VACUUM PRESSURE SENSOR SIGNAL CIRCUIT






1. Turn ignition off.
2. Reconnect Vacuum Pressure Sensor harness connector.
3. Reconnect Anti-Lock Brake Module harness connector.

NOTE: Care should be taken to preserve connector seal when backprobing the harness connector.

4. Backprobe (B32) Vacuum Pressure Sensor Signal at the Vacuum Pressure Sensor.
5. Turn ignition on.
6. Measure the voltage of the (B32) Vacuum Pressure Sensor Signal circuit at the Vacuum Pressure Sensor harness connector.

Is the voltage above 0.4 of a volt?

Yes
- Go To 8

No
- Go To 9

8. (B32) VACUUM PRESSURE SENSOR SIGNAL CIRCUIT






1. Start engine and allow to idle.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

2. Depress brake pedal.
3. Measure the voltage of the (B32) Vacuum Pressure Sensor Signal circuit at the Vacuum Pressure Sensor harness connector.

Is the voltage above 3.1 volts?

Yes
- Go To 10

No
- Go To 11

9. (B32) VACUUM PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND






1. Turn ignition off.
2. Disconnect the Anti-Lock Module harness connector.
3. Disconnect the Vacuum Pressure Sensor harness connector.
4. Measure the resistance between ground and the (B32) Vacuum Pressure Sensor Signal circuit at the Vacuum Pressure Sensor harness connector.

Is the resistance below 5.0 Ohms?

Yes
- Replace Vacuum Pressure Sensor.
- Perform ABS VERIFICATION TEST.

No
- Repair the (B32) Vacuum Pressure Sensor Supply circuit for a short to ground.
- Perform ABS VERIFICATION TEST.

10. (B32) VACUUM PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE






1. Turn ignition on.
2. Measure the voltage of the (B32) Vacuum Pressure Sensor Signal circuit at the Vacuum Pressure Sensor harness connector.

Is the voltage greater than 3.1 volts?

Yes
- Repair the (B32) Vacuum Pressure Sensor Supply circuit for a short to voltage.
- Perform ABS VERIFICATION TEST.

No
- Replace Vacuum Pressure Sensor.
- Perform ABS VERIFICATION TEST.

11. (B32) VACUUM PRESSURE SENSOR SIGNAL CIRCUIT OPEN






1. Turn ignition off.
2. Measure the resistance of the (B32) Vacuum Pressure Sensor Signal circuit from the Vacuum Pressure harness connector to the Anti-Lock Brake Module harness connector.

Is the resistance below 5.0 Ohms?

Yes
- Go To 12

No
- Repair the (B32) Vacuum Pressure Sensor Signal circuit for an open.
- Perform ABS VERIFICATION TEST.

12. ANTI-LOCK BRAKE MODULE

NOTE: Before continuing, check the ABM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

1. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?

Yes
- Repair as necessary.
- Perform ABS VERIFICATION TEST.

No
- Replace the Anti-Lock Brake Module per Service Information.
- Perform ABS VERIFICATION TEST.