DTC U1170: Lost Communication With Brake System Control Module PU-CAN

DTC detecting condition: 

No data is received from EBB control module.

Trouble symptom: 

ABS warning light and VDC warning light illuminate.

1. CHECK CAN COMMUNICATION HARNESS. 

   Perform the basic diagnostic procedure to check for fault in CAN communication harness. Refer to LAN SYSTEM (DIAGNOSTICS) (HEV)>BASIC DIAGNOSTIC PROCEDURE .

   Was the basic diagnostic procedure performed up to step 7?

   Yes:  Go to  2.

   No:  Perform the basic diagnostic procedure. Refer to LAN SYSTEM (DIAGNOSTICS) (HEV)>BASIC DIAGNOSTIC PROCEDURE .

2. CHECK DTC (OTHER THAN U-CODE). 

   Check the displayed DTC.

   Is DTC other than U*** displayed? (Current malfunction)

   Yes:  Perform the diagnosis for DTCs other than the displayed U-code.

   No:  Go to  3.

3. CHECK DTC (CURRENT MALFUNCTION). 

   Check the displayed DTC.

   Is DTC U1170 displayed? (Current malfunction)

   Yes:  Go to  4.

   No:  Go to  6.

4. CHECK DTC. 
   1. Check CAN communication circuit. Refer to LAN SYSTEM (DIAGNOSTICS) (HEV)>CAN COMMUNICATION CIRCUIT CHECK .
   2. Using the Subaru Select Monitor, read all DTCs. Refer to LAN SYSTEM (DIAGNOSTICS) (HEV)>DIAGNOSTIC TROUBLE CODE (DTC)>OPERATION .

   Is DTC U1170 displayed? (Current malfunction)

   Yes:  Go to  5.

   No:  Go to  6.

5. CHECK DTC. 

   Using the Subaru Select Monitor, read all DTCs. Refer to LAN SYSTEM (DIAGNOSTICS) (HEV)>DIAGNOSTIC TROUBLE CODE (DTC)>OPERATION .

   Is DTC U1170 detected in several modules? (Current malfunction)

   Yes:  Replace the brake booster assembly (with the master cylinder). Refer to BRAKE>BRAKE BOOSTER .

   No:  Replace the module that the DTC has been detected.

6. CHECK HARNESS. 
   1. Shake the harness, and check for poor contact.
   2. Using the Subaru Select Monitor, read all DTCs. Refer to LAN SYSTEM (DIAGNOSTICS) (HEV)>DIAGNOSTIC TROUBLE CODE (DTC)>OPERATION .

   Is DTC U1170 displayed? (Current malfunction)

   Yes:  Repair the poor contact of harness, or replace the harness.

   No:  Go to  7.

7. CHECK CONNECTOR. 

   Check the connector used for high speed CAN for poor contact.

   Is there poor contact of connector?

   Yes:  Repair the connector that has poor contact, or replace harness.

   No:  It is possible that temporary poor communication occurs. Delete the DTC.