DTC B18BC: BSI Radar Units Communication Error

Clear the DTCs with the HDS (see General Troubleshooting Information ).
Turn the ignition switch to ON (II), then wait for 10 seconds.
Check for DTCs with the HDS (see General Troubleshooting Information ).
Is DTC B18BC indicated?

YES -Go to step 4.

NO -Intermittent failure, the system is OK at this time.
Turn the ignition switch to LOCK (0).
Disconnect the left BSI radar unit 6P connector.
Disconnect the right BSI radar unit 6P connector.
Disconnect the BSI control unit 16P connector.
Check for continuity between BSI control unit 16P connector terminal No. 3 and body ground.

Fig 1: Checking Continuity Between BSI Control Unit 16P Connector Terminal No. 3 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the wire between the BSI control unit and the branch of the BSI-CAN line (BSI-CAN H).

NO -Go to step 9.
Check for continuity between BSI control unit 16P connector terminals No. 2 and No. 3.

Fig 2: Checking Continuity Between BSI Control Unit 16P Connector Terminals No. 2 And No. 3
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short in the wire between the BSI-CAN H line and the BSI-CAN L line.

NO -Go to step 10.
Turn the ignition switch to ON (II).
Measure the voltage between BSI control unit 16p connector terminal No. 2 and body ground. There should be less than 0.2 V.

Fig 3: Measuring Voltage Between BSI Control Unit 16P Connector Terminal No. 2 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the voltage as specified?

YES -Go to step 12.

NO -Repair a short to power in the wire between the BSI control unit and the branch of the BSI-CAN line (BSI-CAN L).
Turn the ignition switch to LOCK (0).
Reconnect the BSI control unit 16P connector.
Measure the resistance between BSI control unit 16P connector terminals No. 2 and No. 3. There should be an open circuit or at least 1 MΩ.

Fig 4: Measuring Resistance Between BSI Control Unit 16P Connector Terminals No. 2 And No. 3
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the resistance as specified?

YES -Go to step 15.

NO -Replace the BSI control unit
Reconnect the right BSI radar unit 6P connector.
Clear the DTCs with the HDS (see General Troubleshooting Information ).
Turn the ignition switch to ON (II), then wait for 10 seconds.
Check for DTCs with the HDS (see General Troubleshooting Information ).
Is DTC B18BC indicated?

YES -Replace the right BSI radar unit

NO -Replace the left BSI radar unit