DTC B12F3: Power Control Unit Lost Communication With Transmission 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 Checks (2015-17), or Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks (2018-19) .

DTC (Power Control Unit)

1. Problem verification 1

   -1. Clear the DTCs with the HDS.

   - 2. Do this procedure 10 times: Press the engine start/stop switch to select the OFF, ACC, ON, and OFF mode.

   - 3. Check for DTCs with the HDS.

   DTC Description	DTC
   B12F3 Power control unit lost communication with transmission control unit

   Is DTC B12F3 indicated?

   YES 

   Go to step 2.

   NO 

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

2. Open wire check (+B line)

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

   - 2. Disconnect the following connector.

   TCM 58P connector

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

   Test condition	Vehicle OFF (LOCK) mode TCM 58P connector: disconnected
   Test point 1	TCM 58P connector No. 5
   Test point 2	Body ground

   Is there battery voltage?

   YES 

   The +B wire is OK. Go to step 3.

   NO 

   Repair an open or high resistance in the wire.

3. Open wire check (IG line)

   -1. Turn the vehicle to the ON mode.

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

   Test condition	Vehicle ON mode TCM 58P connector: disconnected
   Test point 1	TCM 58P connector No. 58
   Test point 2	Body ground

   Is there battery voltage?

   YES 

   The IG wire is OK. Go to step 4.

   NO 

   Repair an open or high resistance in the wire.

4. Open wire check (GND1, GND2 line)

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

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

   Test condition	Vehicle OFF mode TCM 58P connector: disconnected
   Test point 1	TCM 58P connector No. 1
   Test point 2	Body ground

   Test point 1	TCM 58P connector No. 2
   Test point 2	Body ground

   Is there continuity?

   YES 

   The GND1, GND2 wires are OK. Go to step 5.

   NO 

   Repair an open or high resistance in the wire or poor ground (G101).

5. Shorted wire check (between TCM and body ground)

   -1. Disconnect the following connector.

   Keyless access/TPMS control unit connector C (20P)

   - 2. Check for continuity between the following test points and body ground individually.

   Test condition	Vehicle OFF (LOCK) mode TCM 58P connector: disconnected
   Test point 1	TCM 58P connector No. 56
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short to ground in the wire.

   NO 

   The wire between the TCM and body ground are OK. Go to step 6.

6. Open wire check (between keyless access/TPMS control unit and TCM lines)

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

   Test condition	Vehicle OFF (LOCK) mode Keyless access/TPMS control unit connector C (20P): disconnected TCM 58P connector: disconnected
   Test point 1	Keyless access/TPMS control unit connector C (20P) No. 3
   Test point 2	TCM 58P connector No. 56

   Is there continuity?

   YES 

   The IGN TRX wire is OK. Go to step 7.

   NO 

   Repair an open or high resistance in the wire.

7. Problem verification

   -1. Reconnect the these items:

   Keyless access/TPMS control unit connector C (20P)

   TCM 58P connector

   - 2. With driver's power window open, turn the vehicle to the OFF (LOCK) mode.

   - 3. Do the 12 volt battery terminal disconnection procedure.

   - 4. Wait for at least 10 seconds to clear the DTCs.

   - 5. Do the 12 volt battery terminal reconnection procedure.

   - 6. Turn the vehicle to the ON mode then the OFF (LOCK) mode.

   - 7. Remove all the keyless remotes from inside the vehicle. Hold them outside the open driver's window, at least 20 cm (8.0 in) away from the vehicle.

   - 8. Close all doors, then press the engine start/stop button.

   - 9. The keyless remotes bring to the vehicle inside, during close all doors.

   - 10.Touch the engine start/stop switch with the keyless remote. The buttons on the keyless remote should be facing you.

   - 11.Press the engine start/stop button, and turn the vehicle to the ON mode.

   Does the mode change to ON?

   YES 

   Go to step 8.

   NO 

   Replace the keyless access/TPMS control unit .

8. Problem verification 2

   -1. Clear the DTCs with the HDS.

   - 2. Do this procedure 10 times: Press the engine start/stop switch to select the OFF, ACC, ON, and OFF mode.

   - 3. Check for DTCs with the HDS.

   DTC Description	DTC
   B12F3 Power control unit lost communication with transmission control unit

   Is DTC B12F3 indicated?

   YES 

   Replace the TCM .

   NO 

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