DTC : B12C5

DTC B12C5  : Engine Start/Stop Switch Failure

DTC (Power 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. Press the engine start/stop switch at least twenty times, then wait for at least 20 seconds.

   - 3. Check for DTCs with the HDS.

   DTC Description	DTC
   B12C5 Engine Start/Stop Switch Failure

   Is DTC B12C5 indicated?

   YES 

   Go to step 2.

   NO 

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

2. Determine possible failure area (+B SMART line, SSB GND line, or other)

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

   - 2. Disconnect the following connector.

   Engine start/stop switch 12P connector

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

   Test condition	Vehicle OFF (LOCK) mode Engine start/stop switch 12P connector: disconnected
   Test point 1	Engine start/stop switch 12P connector No. 1
   Test point 2	Engine start/stop switch 12P connector No. 12

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

   Is there battery voltage?

   YES 

   The +B SMART and SSB GND wires are OK. Go to step 3.

   NO 

   Go to step 6.

3. Shorted wire check (SS2-, SS1+ lines)

   -1. Disconnect the following connector.

   Keyless access/TPMS control unit connector B (36P)

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

   Test condition	Vehicle OFF (LOCK) mode Engine start/stop switch 12P connector: disconnected Keyless access/TPMS control unit connector B (36P): disconnected
   Test point 1	Engine start/stop switch 12P connector No. 6
   Test point 2	Body ground

   Test point 1	Engine start/stop switch 12P connector No. 7
   Test point 2	Body ground

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

   Is there continuity?

   YES 

   Repair short to ground in the wire.

   NO 

   The SS2- and SS1+ wires are not shorted. Go to step 4.

4. Open wire check (SS2-, SS1+ lines)

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

   Test condition	Vehicle OFF (LOCK) mode Engine start/stop switch 12P connector: disconnected Keyless access/TPMS control unit connector B (36P): disconnected
   Test point 1	Engine start/stop switch 12P connector No. 6
   Test point 2	Keyless access/TPMS control unit connector B (36P) No. 11 - 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 1	Engine start/stop switch 12P connector No. 7
   Test point 2	Keyless access/TPMS control unit connector B (36P) No. 10 - 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) .

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

   Is there continuity?

   YES 

   The SS2- and SS1+ wires are OK. Go to step 5.

   NO 

   Repair an open or high resistance in the wire.

5. Engine start/stop switch check

   -1. Do the Engine Start/Stop Switch test.

   Is the engine start/stop switch OK?

   YES 

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

   NO 

   Replace the Engine Start/Stop Switch - Removal and Installation .

6. Open wire check (+B SMART line)

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

   Test condition	Vehicle OFF (LOCK) mode Engine start/stop switch 12P connector: disconnected
   Test point 1	Engine start/stop switch 12P connector No. 12
   Test point 2	Body ground

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

   Is there battery voltage?

   YES 

   Repair an open or high resistance in the SSB GND wire.

   NO 

   Repair an open or high resistance in the +B SMART wire.