DTC Troubleshooting: 56-31
DTC 56-31:
 Lost Communication with the ECM/PCM (PGM-FI system) (K24Z3 engine)
NOTE:
  • Before doing this troubleshooting procedure, review SRS Precautions and Procedures and General Troubleshooting Information.
  • Check for any F-CAN and B-CAN communication DTCs, and troubleshoot those DTCs before doing this troubleshooting procedure.
  • Before replacing the SRS unit, check the SRS unit software version with the HDS. If the software version is not the latest, update the SRS unit software and retest.
  1. Clear the DTC memory.
  1. Turn the ignition switch to ON (II), then wait for 10 seconds.
  1. Read the DTC.
Is DTC 53-21 or 56-31 indicated?
YES -
Go to Step 4 .
NO -
Intermittent failure, the system is OK at this time. Go to Troubleshooting Intermittent Failures. If another DTC is indicated, troubleshoot the DTC.
  1. Turn the ignition switch to ON (II), and see if the malfunction indicator lamp (MIL) comes on.
Does the MIL come on?
YES -
Go to the MIL Circuit Troubleshooting.
NO -
Go to Step 5 .
  1. Turn the ignition switch to LOCK (0).
  1. Do the battery terminal disconnection procedure , then wait for 3 minutes.
  1. Disconnect SRS unit connector A (39P) from the SRS unit.
  1. Disconnect ECM/PCM connector A (49P) from the ECM/PCM.
  1. Check for continuity between the No. 16 terminal of the SRS unit connector A (39P) and the No. 4 terminal of ECM/PCM connector A (49P), and between the No. 17 terminal of the SRS unit connector A (39P) and the No. 3 terminal of the ECM/PCM connector A (49P).
Is there continuity?
YES -
Faulty SRS unit or poor connection at SRS unit connector A (39P) and the SRS unit. Check the connection between the connector and the SRS unit. If the connection is OK, replace the SRS unit. ■
NO -
Open in the left engine compartment wire harness or the dashboard wire harness; replace the faulty harness.■