DTC : B2A70-12 (WITHOUT Auto Idle Stop System) (2019 2020 2021)

DTC B2A70-12  : LDW/RDM Switch Signal Circuit Short

NOTE:  Before you troubleshoot, review the general troubleshooting information - Go to: How to Troubleshoot the Road Departure Mitigation (2019 2020 2021) .

DTC (IDAS)

1. Problem verification

   - 1. Turn the vehicle to the ON mode.

   - 2. Clear the DTC with the HDS.

   Clear DTCs

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

   - 4. Turn the vehicle to the ON mode, then press the RDM switch.

   - 5. Check for DTCs with the HDS.

   DTC Description	DTC
   B2A70-12 LDW/RDM Switch Signal Circuit Short

   Is DTC B2A70-12 indicated?

   YES 

   The failure is duplicated. Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Go to intermittent failures troubleshooting - Go to:

   • How to Troubleshoot the Road Departure Mitigation (2019 2020 2021)
   • How to Troubleshoot the Lane Keeping Assist System (LKAS) (2019 2020 2021)

2. Fuse check

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

   - 2. Check the following fuse.

   Fuse No. C28 -

   Refer to: Fuse to Components Index (Without Auto Idle Stop System) (2019 2020 2021)

   Is the fuse OK?

   YES 

   The fuse is OK. Reinstall the fuse, then go to step 3.

   NO 

   Replace the fuse. Turn the vehicle to the ON mode, then the OFF (LOCK) mode. If the fuse blows again, repair the short to ground on the No. C28 fuse circuit.

3. Open wire check (IG1 OPTION line)

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

   - 2. Disconnect the following connector.

   RDM switch 12P connector

   - 3. Turn the vehicle to the ON mode.

   - 4. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle ON mode
   	RDM switch 12P connector: disconnected
   Test point 1	RDM switch 12P connector (female terminals) No. 11: (1)
   Test point 2	Body ground

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

   Is there battery voltage?

   YES 

   Go to step 4.

   NO 

   Repair an open in the wire between Under-dash fuse/relay box and the RDM switch.

4. RDM switch check

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

   - 2. Test the RDM switch. Test

   Is the RDM switch OK?

   YES 

   RDM switch is OK. Go to step 5.

   NO 

   Replace the RDM Switch (2019 2020 2021) .

5. Open wire check (LDW SW line)

   - 1. Disconnect the following connector.

   Multipurpose camera unit 20P connector

   - 2. Turn the vehicle to the ON mode.

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

   Test condition	Vehicle OFF mode
   	Multipurpose camera unit 20P connector: disconnected
   	RDM switch 12P connector: disconnected
   Test point 1	Multipurpose camera unit 20P connector No. 8 - Refer to: Multipurpose Camera Unit Connector for Inputs and Outputs (2019 2020 2021)
   Test point 2	RDM switch 12P connector (female terminals) No. 8: (1)

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

   Is there continuity?

   YES 

   Check for loose terminals and poor connections in the multipurpose camera unit 20P connector. If they are OK, replace the Multipurpose Camera Unit .

   NO 

   Repair an open in the wire between the RDM switch and the multipurpose camera unit.