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DTC P0557: Brake Booster Pressure Sensor Circuit Low Input
 
 
 
 
CIRCUIT OPERATION
  • A power voltage of 5 volts is applied to the brake booster pressure sensor connector power terminal from the ECM connector terminal BPS5 and grounded to the ECM connector terminal BPSE from the brake booster pressure sensor connector ground terminal.
  • The sensor signal is inputted to the ECM connector terminal BBPS 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 volts and is less than 16.5 volts.
Judgment Criterion
  • Senor output voltage is 0.3 volt or less for 2 seconds [corresponding to 13 kPa (3.8 in.Hg) 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: )
  • Brake booster pressure sensor failed.
  • Open/shorted brake booster pressure sensor circuit, harness damage or connector damage.
  • ECM failed.
 
 
 
DIAGNOSIS
Required Special Tool:
  • MB991658: Test Harness
STEP 1. Using scan tool (M.U.T.-IIISE), check data list item 171: Brake Booster Pressure Sensor.
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(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 BPS5 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 5.
Go to Step 3.
 
STEP 3. Check of short to ground and open circuit in BPS5 line between brake booster pressure sensor connector and ECM connector.
Is the harness wire in good condition?
Go to Step 4.
Repair the connector(s) or wiring harness. Then go to Step 9.
 
STEP 4. Using scan tool (M.U.T.-IIISE), check data list item 171: Brake Booster Pressure Sensor.
(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 (Refer to Removal and Installation ). Then go to Step 9.
 
STEP 5. Perform voltage measurement at brake booster pressure sensor connector.
(1) Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal BPS5 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.
Repair or replace the connector(s), or check and repair the harness of damage in BPS5 line between brake booster pressure sensor connector and ECM connector. Then go to Step 9.
 
STEP 6. Measure the sensor output voltage at brake booster pressure sensor harness side connector.
(1) Use special tool test harness (MB991658) 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 BBPS 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 8.
Go to Step 7.
 
STEP 7. Check of short circuit to ground in BBPS line between brake booster pressure sensor connector and ECM connector.
Is the harness wire in good condition?
Replace the brake booster pressure sensor. Then go to Step 9.
Repair the connector(s) or wiring harness. Then go to Step 9.
 
STEP 8. Check of open circuit and harness damage in BBPS line between brake booster pressure sensor connector and ECM connector.
Is the harness wire in good condition?
Go to Step 4.
Repair or replace the connector(s), or check and repair the harness of open circuit and damage in BBPS line between brake booster pressure sensor connector and ECM connector. Then go to Step 9.
 
STEP 9. Using scan tool (M.U.T.-IIISE), read the diagnostic trouble code (DTC).
(1) Turn the ignition switch to the "ON" position.
(2) After the DTC has been deleted, read the DTC again.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC P0557 set?
Retry the troubleshooting.
The inspection is complete.