SRS System

Control System DTCs

SRS DTC Troubleshooting: 56-25

DTC 56-25 : Lost Communication With the Gauge Control Module

NOTE:
* Before doing this troubleshooting procedure, find out if the vehicle was in a collision. If so, verify that all the required components were replaced with new components, of the correct part number, and that they were properly installed Service and Repair.
* Before doing this troubleshooting procedure, review SRS Precautions and Procedures Service and Repair, General Troubleshooting Information Reading and Clearing Diagnostic Trouble Codes, and Battery Terminal Disconnection and Reconnection Procedures.
* 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 Programming and Relearning, and retest.


1. Body electrical system check:

-1. Check for any F-CAN and B-CAN communication DTCs with the HDS.

Are there any communication DTCs?
-YES- Go to the appropriate DTC troubleshooting.
-NO- Go to step 2.

2. Brake system indicator check:

-1. Release the parking brake, turn the ignition switch to ON (II), and see if the brake system indicator comes on for 2 seconds and then goes off.

Does the brake system indicator come on and then go off after 2 second?
-YES- Go to step 3.
-NO- Do the gauge control module self-diagnostic function. If gauge control module has the problem, replace the gauge control module Service and Repair, then clear the DTC, and retest. If the DTC is still present, replace the SRS unit Service and Repair.

3. DTC check:

-1. Clear the DTCs with the HDS Reading and Clearing Diagnostic Trouble Codes.

-2. Turn the ignition switch to ON (II), then wait for 10 seconds.

-3. Check for DTCs with the HDS Reading and Clearing Diagnostic Trouble Codes.

Is DTC 56-25 indicated?
-YES- Go to step 4.
-NO- Intermittent failure, the system is OK at this time. Go to Troubleshooting Intermittent Failures Reading and Clearing Diagnostic Trouble Codes. If another DTC is indicated, troubleshoot the DTC.

4. Open wire check (F CAN-H, F CAN-L lines):

-1. Turn the ignition switch to LOCK (0).

-2. Disconnect the negative cable from the battery, then wait at least 3 minutes.

-3. Disconnect the following connectors.






-4. Check for continuity between test points 1 and 2.














Is there continuity?
-YES- The F CAN-H, F CAN-L wires are OK. Faulty SRS unit or poor connection at SRS unit connector A (39P) and the SRS unit. Check the connection; if the connection is OK, replace the SRS unit Service and Repair. If the DTC does not clear, replace the dashboard wire harness.
-NO- Open in the harness between SRS unit connector A (39P) terminal No. 20 and gauge control module 32P connector terminal No. 19, or between SRS unit connector A (39P) terminal No. 21 and gauge control module 32P connector terminal No. 20; replace the dashboard wire harness, then clear the DTC.