DTC B1931: BackUp Control Unit No Response
| DTC Description | DTC |
|---|---|
| B1931 Backup Control Unit No Response |
DTC (Backup Control Unit)
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. Open the driver's window all the way down, and close all the doors, then turn the vehicle to the OFF (LOCK) mode.
3. Remove all the keyless remotes from inside the vehicle. Hold one keyless remote outside of the opened driver's window at least 7.9 in (20 cm) away from the vehicle.
4. With holding the keyless remote outside of the opened driver's window, press the engine start/stop switch, and wait for 30 seconds. Repeat this procedure a total of 5 times.
5. Check for DTCs with the HDS.
DTC Description DTC B1931 Backup Control Unit No Response Is DTC B1931 indicated?
YES
Go to step 2.
NO
Intermittent failure, the system is OK at this time. Check for loose or poor connections.
- 2. Connector check:
1. Turn the vehicle to the OFF (LOCK) mode.
2. Check for loose connections in the engine start/stop switch 10P connector.
Is the connections OK?
YES
Go to step 3.
NO
Repair the poor connection of engine start/stop switch 10P connector, and then recheck the system.
- 3. Keyless access control unit SS1 (+), SS2 (-) lines check:
1. Disconnect the following connector.
Keyless access control unit 24P connector 2. Turn the vehicle to the ON mode, and keep pressing the engine start/stop button.
3. Measure the voltage between test points 1 and 2.
Test condition Vehicle ON mode Keyless access control unit connector B (28P): disconnected
Test point 1 Keyless access control unit connector B (28P) No. 8 Test point 2 Keyless access control unit connector B (28P) No. 12 Is there battery voltage when the engine start/stop button is pressed?
YES
Go to step 5.
NO
Go to step 4.
- 4. Open wire check (SS1 (+), SS2 (-) lines):
1. Turn the vehicle to the OFF (LOCK) mode.
2. Test the engine start/stop switch .
Is the engine start/stop switch OK?
YES
Repair an open or high resistance in the wire.
NO
The SS1 (+) and SS2 (-) wires are OK. Replace the engine start/stop switch .
- 5. Engine start/stop switch SS SW VCONT line check:
1. Turn the vehicle to the OFF (LOCK) mode.
2. Keyless access control unit connector B (28P)
3. Turn the vehicle to the ON mode.
4. Measure the voltage between test points 1 and 2.
Test condition Vehicle ON mode Test point 1 Engine start/stop switch 10P connector No. 7 Test point 2 Body ground Is there battery voltage?
YES
Go to step 6.
NO
Go to step 8.
- 6. Shorted wire check (DIN/DOUT, DCK lines):
1. Turn the vehicle to the OFF (LOCK) mode.
2. Disconnect the following connectors.
Keyless access control unit connector B (28P) Engine start/stop switch 10P connector
3. Check for continuity between test points 1 and 2 individually.
Test condition Vehicle OFF (LOCK) mode Keyless access control unit connector B (28P): disconnected
Engine start/stop switch 10P connector: disconnected
Test point 1 Keyless access control unit connector B (28P) No. 24 Test point 2 Body ground Test point 1 Keyless access control unit connector B (28P) No. 23 Test point 2 Body ground Is there continuity?
YES
Repair a short to ground in the wire.
NO
The DIN/DOUT and DCK wires are not shorted. Go to step 7.
- 7. Open wire check (DIN/DOUT, DCK lines):
1. Check for continuity between test points 1 and 2 respectively.
Test condition Vehicle OFF (LOCK) mode Keyless access control unit connector B (28P): disconnected
Engine start/stop switch 10P connector: disconnected
Test point 1 Keyless access control unit connector B (28P) No. 24 Test point 2 Engine start/stop switch 10P connector No. 9 Test point 1 Keyless access control unit connector B (28P) No. 23 Test point 2 Engine start/stop switch 10P connector No. 10 Is there continuity?
YES
The DIN/DOUT and DCK wires are OK. Replace the keyless access control unit .
NO
Repair an open or high resistance in the wire.
- 8. Shorted wire check (SS SW VCONT line):
1. Turn the vehicle to the OFF (LOCK) mode.
2. Disconnect the following connector.
Keyless access control unit connector B (28P) Engine start/stop switch 10P connector
3. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Keyless access control unit connector B (28P): disconnected
Engine start/stop switch 10P connector: disconnected
Test point 1 Keyless access control unit connector B (28P) No. 25 Test point 2 Body ground Is there continuity?
YES
Repair a short to ground in the wire.
NO
The SS SW VCONT wire is not shorted. Go to step 9.
- 9. Open wire check (SS SW VCONT line):
1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Keyless access control unit connector B (28P): disconnected
Engine start/stop switch 10P connector: disconnected
Test point 1 Keyless access control unit connector B (28P) No. 25 Test point 2 Engine start/stop switch 10P connector No. 7 Is there continuity?
YES
The SS SW VCONT wire is OK. Replace the keyless access control unit .
NO
Repair an open or high resistance in the wire.