DTC 59: F-CAN B Communication Error

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 for DTCs with the HDS (see HOW TO CLEAR DTCS ).
Are DTCs 59 and 60 indicated?

YES -Go to DTC 60 troubleshooting (see DTC 60: F-CAN A COMMUNICATION ERROR ).

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 59 indicated?

YES -Go to step 6.

NO -Intermittent failure, the system is OK at this time.
Turn the ignition switch to LOCK (0).
Disconnect these connectors:
- ACC unit 20P (see ADAPTIVE CRUISE CONTROL (ACC) UNIT REMOVAL/INSTALLATION ).
- VSA modulator-control unit 46P (see VSA MODULATOR-CONTROL UNIT REMOVAL AND INSTALLATION ).
- PCM B (49P) (see PCM REPLACEMENT ).
Turn the ignition switch to ON (II).
Measure the voltage between body ground and ACC unit 20P connector terminals No. 7 and No. 18 individually. There should be less than 0.2 V.

Fig 1: Measuring Voltage Between Body Ground And Unit 20P Connector Terminals No. 7 And No. 18
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the voltage as specified?

YES -Go to step 11.

NO -Repair a short to power in the wire between the ACC unit and the branch of the F-CAN B line (F-CAN B H, F-CAN B L).
Measure the resistance between body ground and ACC unit 20P connector terminals No. 7 and No. 18 individually. There should be an open circuit or at least 1 MΩ.

Fig 2: Measuring Resistance Between Body Ground And ACC Unit 20P Connector Terminals No. 7 And No. 18
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the resistance as specified?

YES -Go to step 11.

NO -Repair a short to ground in the wire between the ACC unit and the branch of the F-CAN B line (F-CAN B H, F-CAN B L).
Measure the resistance between ACC unit 20P connector terminals No. 7 and No. 18. There should be an open circuit or at least 1 MΩ.

Fig 3: Measuring Resistance Between ACC Unit 20P Connector Terminals No. 7 And No. 18
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the resistance as specified?

YES -Go to step 12.

NO -Repair a short in the wires between the ACC unit and the branch of the F-CAN B line (F-CAN B H, F-CAN B L).
Check for continuity between ACC unit 20P connector terminal No. 7 and VSA modulator-control unit 46P connector terminal No. 22, and between ACC unit 20P connector terminal No. 18 and VSA modulator-control unit 46P connector terminal No. 1.

Fig 4: Measuring Resistance Between ACC Unit 20P Connector And VSA Modulator-Control Unit 46P Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Faulty ACC unit; replace the ACC unit (see ADAPTIVE CRUISE CONTROL (ACC) UNIT REMOVAL/INSTALLATION ).

NO -Repair an open in the wire between the ACC unit and the branch of the F-CAN B line (F-CAN B H, F-CAN BL).