DTC : B1649

DTC B1649  : Driver Side Rear Passenger Door LF Antenna circuit short

DTC (Keyless Access Control Unit)

NOTE:  If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Go to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks .

1. Problem verification

   - 1. Clear the DTCs with the HDS.

   Clear DTCs

   - 2. Select the KEYLESS ACCESS CONTROL UNIT from the ONE-PUSH START system select menu with the HDS, and enter the SELF CHECK.

   One-Push - KEYLESS ACCESS CONTROL UNIT - SELF CHECK

   - 3. Do the SELF CHECK.

   - 4. Check for DTCs with the HDS.

   DTC Description	DTC
   B1649 DRIVER SIDE REAR PASSENGER DOOR LF ANTENNA CIRCUIT SHORT

   Is DTC B1649 indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for loose or poor connections.

2. Shorted wire check (RL WHEEL LF+, RL WHEEL LF- lines)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Disconnect the following connectors.

   Keyless access/TPMS control unit connector A (32P)

   Left-rear LF antenna/initiator 2P connector

   - 3. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode Keyless access/TPMS control unit connector A (32P): disconnected Left-rear LF antenna/initiator 2P connector: disconnected
   Test point 1	Keyless access/TPMS control unit connector A (32P) No. 16 - Refer to: Keyless Access/TPMS Control Unit Connector for Inputs and Outputs (2016 2017 2018) or Keyless Access/TPMS Control Unit Connector for Inputs and Outputs (2019 2020 2021) .
   Test point 2	Body ground

   Test point 1	Keyless access/TPMS control unit connector A (32P) No. 32 - Refer to: Keyless Access/TPMS Control Unit Connector for Inputs and Outputs (2016 2017 2018) or Keyless Access/TPMS Control Unit Connector for Inputs and Outputs (2019 2020 2021) .
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short to ground in the wire.

   NO 

   The RL WHEEL LF+ and RL WHEEL LF- wires are not shorted. Go to step 3.

3. Shorted wire check (RL WHEEL LF+ line to RL WHEEL LF- line)

   -1. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode Keyless access/TPMS control unit connector A (32P): disconnected Left-rear LF antenna/initiator 2P connector: disconnected
   Test point 1	Keyless access/TPMS control unit connector A (32P) No. 16 - Refer to: Keyless Access/TPMS Control Unit Connector for Inputs and Outputs (2016 2017 2018) or Keyless Access/TPMS Control Unit Connector for Inputs and Outputs (2019 2020 2021) .
   Test point 2	Keyless access/TPMS control unit connector A (32P) No. 32 - Refer to: Keyless Access/TPMS Control Unit Connector for Inputs and Outputs (2016 2017 2018) or Keyless Access/TPMS Control Unit Connector for Inputs and Outputs (2019 2020 2021) .

   Is there continuity?

   YES 

   Repair a short in RL WHEEL LF+ wire to RL WHEEL LF- wire.

   NO 

   The RL WHEEL LF+ and RL WHEEL LF- wires are OK. Go to step 4.

4. Keyless access/TPMS control unit RL WHEEL LF+, RL WHEEL LF- line output check

   -1. Reconnect the following connector.

   Keyless access/TPMS control unit connector A (32P)

   - 2. Turn the vehicle to the ON mode.

   - 3. Select KEYLESS ACCESS CONTROL UNIT from the ONE-PUSH START system select menu with the HDS, and enter FUNCTIONAL TESTS.

   One-Push - KEYLESS ACCESS CONTROL UNIT - FUNCTIONAL TESTS

   - 4. Connect the voltmeter to test points 1 and 2.

   Test condition	Vehicle ON mode Left-rear LF antenna/initiator 2P connector: disconnected
   Test point 1	Left-rear LF antenna/initiator 2P connector No. 2
   Test point 2	Left-rear LF antenna/initiator 2P connector No. 1

   Courtesy of HONDA, U.S.A., INC.

   - 5. Select DRIVER SIDE REAR (DOOR) ANTENNA L DC OUTPUT with the HDS.

   Is there voltage?

   YES 

   Faulty left-rear LF antenna/initiator; replace the Keyless Access LF Antenna/Initiator (Left-Rear) Removal and Installation .

   NO 

   Replace the Keyless Access/TPMS Control Unit - Removal and Installation .