DTC B1663: Rear Interior LF Antenna Circuit Short

Clear the DTCs with the HDS.
Select the TROUBLE CODE MENU from the HDS, then enter the SELF CHECK.
Do the SELF CHECK.
Check for DTCs with the HDS.
Is DTC B1663 indicated?

YES - Go to step 5.

NO - Intermittent failure, the system is OK at this time. Check for loose or poor connections at the keyless access control unit and rear interior antenna.
Turn the ignition switch OFF.
Disconnect keyless access control unit connector B (24P).
Disconnect the rear interior LF antenna 2P connector.
Check for continuity between body ground and keyless access control unit connector B (24P) terminals No. 2 and No. 3 individually.

Fig 1: Checking Continuity Between Body Ground And Keyless Access Control Unit Connector B (24P) Terminals No. 2 And No. 3
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair a short to ground in the wire.

NO - Go to step 9.
Reconnect keyless access control unit connector B (24P).
Connect the voltmeter between rear interior LF antenna 2P connector terminals No. 1 and No. 2.

Fig 2: Checking Voltage Between Rear Interior LF Antenna 2P Connector Terminals No. 1 And No. 2
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch ON (II).
Select the FUNCTION TEST MENU from the HDS, and do the REAR INTERIOR ANTENNA L DC OUTPUT.
Is there voltage?

YES - Replace the rear interior LF antenna.

NO - Replace the keyless access control unit.