P0557

DTC Troubleshooting: 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 PCM.�

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

4. Disconnect the 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 PCM connector A (44P).

11. Check for continuity between PCM connector A terminal No. 19 and brake booster pressure sensor A 3P connector terminal No. 1.





Is there continuity?

YES -

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

NO -

Repair an open in the wire between the PCM(A19) and brake booster pressure sensor A.�

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

13. Jump the SCS line with the HDS.

14. Disconnect 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 PCM and brake booster pressure sensor A.�

NO -

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