Circuit/System Testing

Ignition ON.
Verify that DTCs P0556, P0557, or P0558 are not set.
- If any of the DTCs are set
  Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Go to next step: If none of the DTCs are set
Verify that the brake booster vacuum system has no damage, leakage or incorrect installation.
- If damage, leakage or incorrect installation is found
  Refer to Brake System Vacuum Source Test .
- Go to next step: If the inspection is OK
Ignition OFF/Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the B19B Brake Booster Vacuum Sensor. It may take up to 2 min for all vehicle systems to power down.
Test for less than 10 Ω between the low reference circuit terminal 2 and ground.
- If 10 Ω or greater
1. Disconnect the harness connector at the K20 Engine Control Module.
2. Test for less than 2 Ω in the low reference circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the K20 Engine Control Module.
- Go to next step: If less than 10 Ω
Ignition ON/Vehicle in Service Mode.
Test for 4.8 - 5.2 V between the 5 V reference circuit terminal 3 and ground.
- If less than 4.8 V
1. Ignition OFF/Vehicle OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the 5 V reference circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
3. Test for less than 2 Ω in the 5 V reference circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the K20 Engine Control Module.
- If greater than 5.2 V
1. Ignition OFF/Vehicle OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the 5 V reference circuit and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - If less than 1 V, replace the K20 Engine Control Module.
- Go to next step: If between 4.8 - 5.2 V
Test for less than 1 V between the B19B Brake Booster Vacuum Sensor signal circuit terminal 1 and ground.
- If greater than 1 V
1. Ignition OFF/Vehicle OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - If less than 1 V, replace the K20 Engine Control Module.
- Go to next step: If less than 1 V
Ignition OFF/Vehicle OFF, disconnect the harness connector at the K20 Engine Control Module.
Test for infinite resistance between the B19B Brake Booster Vacuum Sensor signal circuit terminal 1 and ground.
- If less than infinite resistance
  Repair the short to ground on the circuit.
- Go to next step: If infinite resistance
Test for less than 2 Ω in the B19B Brake Booster Vacuum Sensor signal circuit end to end.
- If 2 Ω or greater
  Repair the open/high resistance in the circuit.
- Go to next step: If less than 2 Ω
Replace the B19B Brake Booster Vacuum Sensor.