DTC U1676: Lin Communication Bus Error Hybrid Powertrain Control Module: Wiring Diagram

WARNING: This page is about a different car, the 2015 Subaru XV Crosstrek. However, it is still accessible from the selected car via links, so may be relevant.

Hybrid system < Ref. to WIRING DIAGRAM , Hybrid Electric Vehicle System.>

Fig 1: LIN Communication Bus Error Hybrid Powertrain Control Module - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DTC PROCEDURE

Step	Check	Yes	No
1 CHECK BATTERY. Check the 12 volt engine restart battery.	Is the condition normal?	Go to step 2 .	Charge or replace the 12 volt engine restart battery.
2 CHECK MODULES. Disconnect the integrated starter generator connector. Perform the Clear Memory Mode. < Ref. to HYBRID POWERTRAIN CONTROL SYSTEM , OPERATION, Clear Memory Mode.> Read the DTC again. < Ref. to HYBRID POWERTRAIN CONTROL SYSTEM , OPERATION, Read Diagnostic Trouble Code (DTC).>	Is DTC U1676 detected? (current malfunction)	Go to step 3 .	Replace the integrated starter generator. < Ref. to INTEGRATED STARTER GENERATOR (ISG) .>
3 CHECK MODULES. Turn the ignition switch to OFF. Disconnect the 12V engine restart battery sensor connector. Perform the Clear Memory Mode. < Ref. to HYBRID POWERTRAIN CONTROL SYSTEM , OPERATION, Clear Memory Mode.> Read the DTC again. < Ref. to HYBRID POWERTRAIN CONTROL SYSTEM , OPERATION, Read Diagnostic Trouble Code (DTC).>	Is DTC U1676 detected? (current malfunction)	Go to step 4 .	Replace the 12V engine restart battery sensor. < Ref. to BATTERY SENSOR .>
4 CHECK MODULES. Turn the ignition switch to OFF. Disconnect the active grille shutter connector. Perform the Clear Memory Mode. < Ref. to HYBRID POWERTRAIN CONTROL SYSTEM , OPERATION, Clear Memory Mode.> Read the DTC again. < Ref. to HYBRID POWERTRAIN CONTROL SYSTEM , OPERATION, Read Diagnostic Trouble Code (DTC).>	Is DTC U1676 detected? (current malfunction)	Go to step 5 .	Replace the active grille shutter.
5 CHECK HARNESS (OPEN CIRCUIT). Turn the ignition switch to OFF. Disconnect the HPCM connector. Using a tester, measure the resistance between the HPCM connector and connector of each unit. Connector & terminal (B605) No. 4 - (F157) No. 3: (B605) No. 4 - (B598) No. 2: (B605) No. 4 - (E163) No. 4:	Is the resistance less than 1 Ω?	Go to step 6 .	Repair open circuit of the harness between HPCM connector and connector of each unit.
6 CHECK HARNESS (SHORT TO GROUND). Using a tester, measure the resistance between HPCM connector and chassis ground. Connector & terminal (B605) No. 4 - Chassis ground:	Is the resistance 1 MΩ or more?	Go to step 7 .	Repair ground short circuit of harness between the HPCM connector and the integrated starter generator connector.
7 CHECK HARNESS (SHORT TO POWER). Using a tester, measure the voltage between the HPCM connector and chassis ground. Connector & terminal (B605) No. 4 (+) - Chassis ground (-):	Is the voltage less than 1 V?	Replace the HPCM. < Ref. to HYBRID POWERTRAIN CONTROL MODULE .>	Repair the short circuit to power in harness between the HPCM connector and the integrated starter generator connector.