DTC 111: Lost Communication with the PCM (A/T System)

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.

Check the MIL on the gauge control module (see GENERAL TROUBLESHOOTING INFORMATION ).
Does the MIL stay on?

YES -Go to the PGM-FI system's general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).

NO -Go to step 2.
Clear the DTCs with the HDS (see HOW TO CLEAR DTCS ).
Turn the ignition switch to ON (II), then wait for 10 seconds.
Press the MAIN switch ON.
Check for DTCs with the HDS (see HOW TO CLEAR DTCS ).
Is DTC 111 indicated?

YES -Go to step 6.

NO -Intermittent failure, the system is OK at this time.
Test-drive the vehicle, and check the data of vehicle speed signal with the HDS.
Does HDS correspond to the vehicle speed indicated in the meter?

YES -Go to step 12.

NO -Go to step 7.
Turn the ignition switch to LOCK (0).
Disconnect the ACC unit 20P connector.
Jump the SCS line with the HDS, then disconnect PCM connector B (49P) (see PCM REPLACEMENT ).
Check for continuity between ACC unit 20P connector terminal No. 7 and PCM connector B (49P) terminal No. 47.

Fig 1: Checking Continuity Between Acc Unit 20P Connector And PCM Connector B (49P)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 11.

NO -Repair an open in the wire between the ACC unit and the branch of the F-CAN B line (F-CAN B H).
Check for continuity between ACC unit 20P connector terminal No. 18 and PCM connector B (49P) terminal No. 48.

Fig 2: Checking Continuity Between ACC Unit 20P Connector And PCM Connector B (49P)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Faulty PCM; replace the PCM (see PCM REPLACEMENT ).

NO -Repair an open in the wire between the ACC unit and the branch of the F-CAN B line (F-CAN B L).
Turn the ignition switch to LOCK (0).
Disconnect the ACC unit 20P connector.
Jump the SCS line with the HDS, then disconnect PCM connector A (49P) (see PCM REPLACEMENT ).
Check for continuity between ACC unit 20P connector terminal No. 10 and PCM connector A (49P) terminal No. 48.

Fig 3: Checking Continuity Between Acc Unit 20P Connector And PCM Connector A (49P)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 16.

NO -Repair an open in the wire between the ACC unit and the branch of the F-CAN A line (F-CAN A H).
Check for continuity between ACC unit 20P connector terminal No. 20 and PCM connector A (49P) terminal No. 49.

Fig 4: Checking Continuity Between ACC Unit 20P Connector And PCM Connector A (49P)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Faulty PCM; replace the PCM (see PCM REPLACEMENT ).

NO -Repair an open in the wire between the ACC unit and the branch of the F-CAN A line (F-CAN A L).