DTC B12C5: Engine Start/Stop Switch Failure

NOTE:  If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Refer to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC ChecksBody Electrical Troubleshooting - B-CAN System Diagnosis Test Mode 1 and Test Mode 2 (without the HDS)Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode B - Control Unit Not CommunicatingBody Electrical Troubleshooting - B-CAN System Diagnosis Test Mode C - No DTCs and Output Won't Shut OFFBody Electrical Troubleshooting - B-CAN System Diagnosis Test Mode D - No DTCs and Output Won't Turn ON .

• 1. Problem verification:

  1. Clear the DTCs with the HDS.

  2. Press the engine start/stop button at least 20 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, GND line or other):

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

  2. Disconnect the following connectors.

  Engine start/stop switch 10P connector

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

  Test condition	Vehicle OFF (LOCK) mode Engine start/stop switch 10P connector: disconnected
  Test point 1	Engine start/stop switch 10P connector No. 5
  Test point 2	Engine start/stop switch 10P connector No. 2

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

  Is there battery voltage?

  YES 

  The +B SMART wire and GND wire is OK. Go to step 3.3

  NO 

  Go to step 6.

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

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

  Test condition	Vehicle OFF (LOCK) mode Engine start/stop switch 10P connector: disconnected Keyless access control unit connector B (28P): disconnected
  Test point 1	Engine start/stop switch 10P connector No. 1
  Test point 2	Body ground

  Test point 1	Engine start/stop switch 10P connector No. 4
  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 SS1+ and SS2- wires are not shorted. Go to step 4.

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

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

  Test condition	Vehicle OFF (LOCK) mode Engine start/stop switch 10P connector: disconnected Keyless access control unit connector B (28P): disconnected
  Test point 1	Engine start/stop switch 10P connector No. 4
  Test point 2	Keyless access control unit connector B (28P) No. 12

  Test point 1	Engine start/stop switch 10P connector No. 1
  Test point 2	Keyless access control unit connector B (28P) No. 8

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

  Is there continuity?

  YES 

  The SS1+ and SS2- 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 control unit .

  NO 

  Replace the engine start/stop switch .

• 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 10P connector: disconnected
  Test point 1	Engine start/stop switch 10P connector No. 5
  Test point 2	Body ground

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

  Is there battery voltage?

  YES 

  The +B SMART line is OK. Check for an open or high resistance in the GND wire or poor ground (G502).

  NO 

  Repair an open or high resistance in the wire.