DTC : B2A70-12 (WITH Auto Idle Stop System) (2016 2017 2018)

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

NOTE:  Before you troubleshoot, review the general troubleshooting information - Go to: How to Troubleshoot the Lane Keeping Assist System (LKAS) (2016 2017 2018) 

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 OFF switch.

   - 5. Check for DTCs with the HDS.

   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 - Refer to: How to Troubleshoot the Lane Keeping Assist System (LKAS) (2016 2017 2018) 

   If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the Freeze data/on-board snapshot.

2. Fuse check

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

   - 2. Check the following fuse.

   Fuse	No. D3 (7.5 A)
   Location	Auxiliary under-dash fuse/relay box

   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. D3 (7.5 A) fuse circuit.

3. Open wire check (IG1 ACM (DC/DC) line)

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

   - 2. Disconnect the following connector.

   RDM OFF switch 5P 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 OFF switch 5P connector: disconnected
   Test point 1	RDM OFF switch 5P connector No. 5
   Test point 2	Body ground

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

   Is there battery voltage?

   YES 

   The IG1 ACM (DC/DC) wire is OK. Go to step 4.

   NO 

   Repair an open in the wire between the RDM OFF switch and No. D3 (7.5 A) fuse in the under-dash fuse/relay box.

4. RDM OFF switch check

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

   - 2. Test the RDM OFF switch. Test .

   Is the RDM OFF switch OK?

   YES 

   RDM OFF switch is OK. Go to step 5.

   NO 

   Replace the RDM OFF Switch (2016 2017 2018) .

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 OFF switch 5P connector: disconnected
   Test point 1	Multipurpose camera unit 20P connector No. 8 - Refer to: Multipurpose Camera Unit Connector for Inputs and Outputs (20106 2017 2018)
   Test point 2	RDM OFF switch 5P connector No. 2

   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 OFF switch and the multipurpose camera unit.