P0557

DTC Troubleshooting: P0557, P0557

DTC P0557:

Brake Booster Pressure Sensor A Circuit Low Voltage

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information Initial Inspection and Diagnostic Overview.

1. Turn the ignition switch to ON (II).

2. Check BRAKE BOOSTER PRESSURE SENSOR A in the EVPS DATA LIST with the HDS.

Is there 0.23 V or less?

YES -

Go to step 3.

NO -

Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at brake booster pressure sensor A and the ECM/PCM.

3. Turn the ignition switch to LOCK (0).

4. Disconnect brake booster pressure sensor A 3P connector.

5. Turn the ignition switch to ON (II).

6. Check BRAKE BOOSTER PRESSURE SENSOR A in the EVPS DATA LIST with the HDS.

Is there about 5 V?

YES -

Go to step 7.

NO -

Go to step 12.

7. Measure the voltage between brake booster pressure sensor A 3P connector terminals No. 1 and No. 3.





Is there about 5 V?

YES -

Replace brake booster pressure sensor A Brake Booster Pressure Sensor A Replacement.

NO -

Go to step 8.

8. Turn the ignition switch to LOCK (0).

9. Short the SCS line with the HDS.

10. Disconnect ECM/PCM connector A (44P).

11. Check for continuity between ECM/PCM connector A (44P) terminal No.19 and brake booster pressure sensor A 3P connector terminal No. 3.





Is there continuity?

YES -

Update the ECM/PCM if it does not have the latest software ECM/PCM Update, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM Service and Repair.

NO -

Repair an open in the wire between the ECM/PCM and brake booster pressure sensor A.

12. Turn the ignition switch to LOCK (0).

13. Short the SCS line with the HDS.

14. Disconnect ECM/PCM connector A (44P).

15. Check for continuity between brake booster pressure sensor A 3P connector terminal No. 2 and body ground.





Is there continuity?

YES -

Repair a short in the wire between the ECM/PCM and brake booster pressure sensor A.

NO -

Update the ECM/PCM if it does not have the latest software ECM/PCM Update, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM Service and Repair.