DTC U1221 Can-HS ECM No-Receive Data: Wiring Diagram

CAN communication system. See appropriate SYSTEM WIRING DIAGRAM article.

Fig 1: CAN Communication System - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK CAN COMMUNICATION CIRCUIT. Check CAN communication circuit. Refer to BUS "A" (MAIN-CAN) .	Is CAN communication circuit faulty?	Repair the faulty portion, following the diagnosis procedure.	Go to step 2 .
2 CHECK DTC. Start the engine. Using the Subaru Select Monitor, read DTC of CAN system.	Is U1221 a current malfunction?	Go to step 3 .	It may be a temporary poor contact. Perform the clear memory.
3 CHECK DTC. Using the Subaru Select Monitor, read DTC of all the systems.	Is P1718, C0057, or U0100 detected?	Replace the ECM.	Replace the body integrated unit. Refer to REMOVAL .