[Previous][Next]
DTC P0557: Brake Booster Pressure Sensor Circuit Low Input
 
 
 
 
CIRCUIT OPERATION
  • A power voltage of 5 V is applied to the brake booster pressure sensor connector power terminal from the ECM connector terminal ACP5&BVS5 and grounded to the ECM connector terminal ACPE&BVSE from the brake booster pressure sensor connector ground terminal.
  • The sensor signal is inputted to the ECM connector terminal BVS from the brake booster pressure sensor connector output terminal.
 
 
TECHNICAL DESCRIPTION
  • The brake booster pressure sensor detects a change in brake booster negative pressure and inputs the signal to the ECM.
 
 
DTC SET CONDITIONS
Check Conditions
  • After 2 seconds since the ignition switch is turned ON or since the completion of engine start.
  • Battery positive voltage is more than 10 V and is less than 16.5 V.
Judgment Criterion
  • Senor output voltage is 0.3 V or less for 2 seconds (corresponding to 13 kPa or less of the brake booster pressure).
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Failed brake booster pressure sensor
  • Open/short circuit or harness damage in brake booster pressure sensor circuit or loose connector contact
  • Failed ECM
 
 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
  • MB991348: Test Harness
STEP 1. Using scan tool (M.U.T.-III), check data list.
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Turn the ignition switch to the "ON" position.
(3) Check the following item in the data list. Refer to Data List Reference Table .
  1. Item 171: Brake Booster Pressure Sensor
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Go to Step 2.
 
STEP 2. Measure the sensor supply voltage at brake booster pressure sensor harness side connector.
(1) Disconnect the connector and measure at the harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal ACP5&BVS5 line and ground.
  • Voltage should be between 4.9 and 5.1 volts.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage between 4.9 and 5.1 volts?
Go to Step 6.
Go to Step 3.
 
STEP 3. Measure the power supply voltage at ECM connector.
(1) Disconnect connector, and measure at harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal ACP5&BVS5 and ground.
  • Voltage should be between 4.9 and 5.1 volts.
Is the measured voltage between 4.9 and 5.1 volts?
Go to Step 4.
Repair or replace the connector(s), or check and repair the harness of open circuit in ACP5&BVS5 line between brake booster pressure sensor connector and ECM connector. Then go to Step 10.
 
STEP 4. Check of short to ground between brake booster pressure sensor connector and ECM connector.
Is the harness wire in good condition?
Go to Step 5.
Repair the connector(s) or wiring harness. Then go to Step 10.
 
STEP 5. Using scan tool (M.U.T.-III), check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items in the data list. Refer to Data List Reference Table .
  1. Item 171: Brake Booster Pressure Sensor
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Replace the ECM. Then go to Step 10.
 
STEP 6. Perform voltage measurement at brake booster pressure sensor connector.
(1) Use special tool test harness (MB991348) to connect connector, and measure at pick-up harness.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal ACP5&BVS5 line and ground.
  • Voltage should be between 4.9 and 5.1 volts.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage between 4.9 and 5.1 volts?
Go to Step 7.
Repair or replace the connector(s), or check and repair the harness of damage in ACP5&BVS5 line between brake booster pressure sensor connector and ECM connector. Then go to Step 10.
 
STEP 7. Measure the sensor output voltage at A/C pressure sensor harness side connector.
(1) Use special tool test harness (MB991348) to connect connector, and measure at pick-up harness.
(2) Start up the engine and let it idle for several minutes.
(3) Stop the engine, and turn the ignition switch to the ON position.
(4) Depress the brake pedal several times.
(5) Measure the voltage between terminal BVS line and ground.
  • The more frequently the brake pedal is depressed, the more the voltage is decreased.
(6) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage normal?
Go to Step 9.
Go to Step 8.
 
STEP 8. Check of short to ground in BVS line between brake booster pressure sensor connector and ECM connector.
Is the check result normal?
Replace the brake booster pressure sensor. Then go to Step 10.
Repair the connector(s) or wiring harness. Then go to Step 10.
 
STEP 9. Measure the sensor output voltage at ECM connector by backprobing.
(1) Do not disconnect the connector.
(2) Start up the engine and let it idle for several minutes.
(3) Stop the engine, and turn the ignition switch to the ON position.
(4) Depress the brake pedal several times.
(5) Measure the voltage between terminal BVS line and ground by backprobing.
  • The more frequently the brake pedal is depressed, the more the voltage is decreased.
(6) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage normal?
Go to Step 5.
Repair or replace the connector(s), or check and repair the harness of open circuit, and damage in BVS line between brake booster pressure sensor connector and ECM connector. Then go to Step 10.
 
STEP 10. Using scan tool (M.U.T.-III), check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items in the data list. Refer to Data List Reference Table .
  1. Item 171: Brake Booster Pressure Sensor
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
The inspection is complete.
Retry the troubleshooting.