DTC U1291 (Power Distribution Module)

DTC U1291  : Semiconductor Fuse Relay Module Lost Communication with Relay Control Module

NOTE: 

• If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A .
• According to the detected DTC(s), check for the power circuit and the ground circuit of the control unit which cannot communicate with the power distribution module.
• Refer to the DTC shown on the display, then inspect the connectors and terminals based on the instructions.

DTC (Power Distribution Module)

1. Problem verification

   -1. Turn the vehicle to the ON mode.

   -2. Clear the DTC with the HDS.

   -3. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

   -4. Wait for at least 6 seconds.

   -5. Check for DTCs with the HDS.

   DTC Description	DTC
   U1291 Semiconductor Fuse Relay Module Lost Communication with Relay Control Module

   Are any DTCs indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the transmitting control units and the power distribution module.

2. Open wire check (B-CAN_H line, B-CAN_L line)

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

   -2. Disconnect the receiving control unit connector.

   Power distribution module connector B (14P)

   -3. Disconnect the transmitting control unit connector(s).

   Refer to the DTC shown on the display, then disconnect the connector(s) based on the instructions (see chart).

   DTC	Connector
   U1291	Body control module connector B (36P)

   -4. Check for continuity between the receiving control unit and the transmitting control unit on the B-CAN_H circuit and the B-CAN_L circuit.

   Test condition

   Vehicle OFF (LOCK) mode Power distribution module connector B (14P): disconnected Transmitting control unit connector(s) for indicated DTCs: disconnected

   DTC	Circuit name	Receiving control unit		Transmitting control unit
   		Connector	Terminal	Connector	Terminal
   U1291	B-CAN_H	Power distribution module connector B (14P)	No. 6	Body control module connector B (36P)	No. 20
   	B-CAN_L		No. 7		No. 21

   Is there continuity?

   YES 

   The B-CAN_H wire and the B-CAN_L wire are OK. Refer to the DTC shown on the display, then substitute or replace the control unit based on the instructions (see chart).

   DTC	Operation for transmitting control unit
   U1291	Substitute a known-good body control module , then recheck. If DTC U1291 goes away after substitution, replace the original body control module .

   NO 

   Repair an open in the B-CAN_H wire and/or the B-CAN_L wire between the power distribution module and the transmitting control unit.