DTC 56-21

DTC 56-11: Lost Communication with the PCM (engine message)

DTC 56-21: Lost Communication with the PCM (A/T message)

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.

1. Turn the ignition switch to ON (II), and see if the malfunction indicator lamp (MIL) or D indicator come on.

Does the MIL or D indicator come on?

YES - Go to step 2.

NO - Go to the PGM-FI System MIL circuit troubleshooting or A/T system General Troubleshooting Information.

2. Clear the DTC memory.
3. Turn the ignition switch to ON (II), then wait for 10 seconds.
4. Read the DTC.

Is DTC 56-11 or 56-21 indicated?

YES - Go to step 5.

NO - Intermittent failure, the system is OK at this time. Go to Troubleshooting Intermittent Failures Troubleshooting Intermittent Failures. If another DTC is indicated, troubleshoot the DTC.

5. Turn the ignition switch to LOCK (0).
6. Disconnect the negative cable from the battery, and wait for 3 minutes.
7. Disconnect SRS unit connector A (28P) from the SRS unit.
8. Disconnect PCM connector A (44P) from the PCM.
9. Install a jumper wire between the No. 11 and the No. 12 terminals of SRS unit connector A (28P).






10. Measure the resistance between the No. 36 and the No. 37 terminals of PCM connector A (44P). There should be 0 - 1.0 ohm.






Is the resistance as specified?

YES - Faulty SRS unit or poor connection at SRS unit connector A (28P) 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 between the No. 11 terminal of SRS unit connector A (28P) and the No. 36 terminal of PCM connector A (44P), or between the No. 12 terminal of SRS unit connector A (28P) and the No. 37 terminal of PCM connector A (44P); replace the faulty harness.