DTC 21-9x ("x" can be 0 thru 9 or A thru F): Short to Ground in the Driver's Seat Belt Tensioner

WARNING: This page is about a different car, the 2013 Acura MDX, 2012 Acura MDX, 2011 Acura MDX, and 2010 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.

Special Tools Required

SRS Inflator Simulator 07SAZ-TB4011A
SRS Simulator Lead K 070AZ-SNAA200

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 (see COMPONENT REPLACEMENT/INSPECTION AFTER DEPLOYMENT ).
Before doing this troubleshooting procedure, review SRS PRECAUTIONS AND PROCEDURES , GENERAL TROUBLESHOOTING INFORMATION , and Battery Terminal Disconnection and Reconnection (see USING THE GR8 BATTERY DIAGNOSTIC STATION ).
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 (see SRS UNIT UPDATE ), and retest.

Clear the DTCs with the HDS (see HOW TO CLEAR DTCS ).
Turn the ignition switch to ON (II), then wait for 10 seconds.
Check for DTCs with the HDS (see HOW TO CLEAR DTCS ).
Is DTC 21-9x 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.
Turn the ignition switch to LOCK (0).
Disconnect the negative cable from the battery, then wait at least 3 minutes.
Remove the B-pillar lower trim (see B-PILLAR UPPER/LOWER TRIM ), then disconnect the floor wire harness 4P connector (A) from the driver's seat belt tensioner.

Fig 1: Identifying Floor Wire Harness 4P Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Connect the SRS inflator simulator (2 Ω connectors) and simulator lead K to the floor wire harness.
Reconnect the negative cable to the battery.
Clear the DTCs with the HDS (see HOW TO CLEAR DTCS ).
Check for DTCs with the HDS (see HOW TO CLEAR DTCS ).
Is DTC 21-9x indicated?

YES -Go to step 11.

NO -Short to ground in the driver's seat belt tensioner; replace the driver's seat belt (see FRONT SEAT BELT REPLACEMENT ), then clear the DTC.
Turn the ignition switch to LOCK (0).
Disconnect the negative cable from the battery, then wait at least 3 minutes.
Disconnect SRS unit connector B (39P) from the SRS unit (see DISCONNECTING SYSTEM CONNECTORS ).
Disconnect the simulator lead from the floor wire harness.
Measure the resistance between body ground and SRS unit connector B (39P) terminals No. 12 and No. 13 individually.

Fig 2: Measuring Resistance Between Body Ground And SRS Unit Connector B (39P) Terminals No. 12 And No. 13
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there an open circuit or at least 1 MΩ?

YES -Faulty SRS unit or poor connection at SRS unit connector 8 (39P) and the SRS unit. Check the connection; if the connection is OK, replace the SRS unit (see SRS UNIT REPLACEMENT ).

NO -Short to ground in the floor wire harness; replace the floor wire harness, then clear the DTC.