DTC 2-1: OnStar Control Unit Lost Communication With SRS Unit (Collision Detection Signal Error)

NOTE: Check battery charge and condition, and check connector for loose or poor connection and pinfits.

Delete all DTCs from the OnStar control unit (see HOW TO DELETE THE DTC ).
Turn the ignition switch OFF, and then back to ON (II).
Enter the self-diagnostic mode and check for the DTCs.
Is DTC 2-1 indicated?
1. YES - Go to step 4.
2. NO - Intermittent failure. The system is OK at this time. Check for loose or poor connections.
Check the SRS indicator.
Does the SRS indicator come on and stay on?
1. YES - Go to SRS troubleshooting (see PRECAUTIONS AND PROCEDURES ).
2. NO - Go to step 5.
Turn the ignition switch OFF.
Disconnect the OnStar control unit connector A (22P).
Disconnect the SRS unit connector A (28P).
Check for continuity between the OnStar control unit connector A (22P) No. 14 terminal and body ground.

Fig 1: Checking Continuity Between OnStar Control Unit Connector A (22P) No. 14 Terminal And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Repair a short to ground in the wire.
2. NO - Go to step 9.
Turn the ignition switch ON (II).
Measure voltage between the OnStar control unit connector A (22P) No. 14 terminal and body ground.

Fig 2: Measuring Voltage Between OnStar Control Unit Connector A (22P) No. 14 Terminal And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there more than 0.1 V?
1. YES - Repair a short to power in the wire.
2. NO - Go to step 11.
Turn the ignition switch OFF.
Check for continuity between the OnStar control unit connector A (22P) No. 14 terminal and SRS unit connector A (28P) No. 21 terminal.

Fig 3: Checking Continuity Between OnStar Control Unit Connector A (22P) No. 14 Terminal
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Replace the SRS unit. If the problem does not go away, replace the OnStar unit.
2. NO - Repair an open in the wire.