DTC P3123-87: Lost Communication With Drive Motor Control Module "A" From Hybrid/EV Control Module Missing Message: Notes

1. - 

Outline of diagnosis: 

Fault of communication signal reception from MG unit (outside communication standard)

(1 trip detection logic)

Trouble symptom: 

Hybrid system stopped

Wiring diagram: 

Hybrid system Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>HYBRID ELECTRIC VEHICLE SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK FUSE (PCM FR)  .
   1. Remove the F/B NO. 24 FUSE from the Relay and fuse box (F/B). Ref. to HYBRID ELECTRIC VEHICLE>RELAY AND FUSE .
   2. Check F/B NO. 24 FUSE.

      Is the F/B NO. 24 FUSE OK?

      Yes: 

      Go to  2.

      No: 

      Go to  9.

2. CHECK DTC  .
   1. Turn to IG ON.
   2. Using the Subaru Select Monitor, perform the clear memory of [P-HEV Hybrid Powertrain Control]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
   3. Read the DTC of [P-HEV Hybrid Powertrain Control] using the Subaru Select Monitor. Ref. to P-HEV HYBRID POWERTRAIN CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

      Is diagnostic related information or DTC P3123-87 displayed?

      Yes: 

      Go to  3.

      No: 

      Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

      NOTE:

      In this case, temporary poor contact of connector, or temporary open or short circuit of the Wire harness may be the cause. 

3. CHECK Wire harness AND CONNECTOR (Inverter with converter assembly POWER SUPPLY CIRCUIT) (OPEN CIRCUIT)  .
   CAUTION:

   Make sure to wear insulated gloves and protective goggles during the work. 

   1. Turn the ignition to OFF.
   2. Check that the Service plug is disconnected. Ref. to HYBRID ELECTRIC VEHICLE>SERVICE PLUG .
   3. Disconnect Inverter with converter assembly connector (HV23).
   4. Using a tester, measure the resistance between Inverter with converter assembly connector and chassis ground.

      Connector and terminal 

      (HV23) No. 4 - Chassis ground:

      (HV23) No. 8 - Chassis ground:

      Is the resistance less than 1 Ω?

      Yes: 

      Go to  4.

      No: 

      Repair or replace the Wire harness between Inverter with converter assembly connector and chassis ground.

4. CHECK Wire harness AND CONNECTOR (Inverter with converter assembly POWER SUPPLY CIRCUIT) (OPEN CIRCUIT)  .
   CAUTION:

   Make sure to wear insulated gloves and protective goggles during the work. 

   1. Connect the Battery (12V) ground terminal. Then, wait at least 2 minutes. Ref. to REPAIR CONTENTS>REPAIR CONTENTS>NOTE>BATTERY .
   2. Turn to IG ON.
   3. Using a tester, measure the voltage between Inverter with converter assembly connector and chassis ground.

      Connector and terminal 

      (HV23) No. 1 (+) - Chassis ground (-):

      (HV23) No. 5 (+) - Chassis ground (-):

      Is the voltage 11 - 14 V?

      Yes: 

      Go to  5.

      No: 

      Repair or replace the Wire harness between Inverter with converter assembly connector and chassis ground.

5. CHECK Wire harness AND CONNECTOR (Inverter with converter assembly - Hybrid vehicle control ECU assembly) (SHORT TO POWER SUPPLY)  .
   CAUTION:

   Make sure to wear insulated gloves and protective goggles during the work. 

   1. Disconnect Hybrid vehicle control ECU assembly connector (B606).
   2. Using a tester, measure the voltage between Inverter with converter assembly connector and chassis ground.

      Connector and terminal 

      (B606) No. 20 (+) - Chassis ground (-):

      (B606) No. 28 (+) - Chassis ground (-):

      Is the voltage less than 1 V?

      Yes: 

      Go to  6.

      No: 

      Repair or replace the Wire harness between Inverter with converter assembly connector and chassis ground.

6. CHECK Wire harness AND CONNECTOR (Inverter with converter assembly - Hybrid vehicle control ECU assembly) (OPEN CIRCUIT)  .
   1. Turn the ignition to OFF.
   2. Disconnect the ground terminal of Battery (12V). Then, wait at least 2 minutes. Ref. to REPAIR CONTENTS>REPAIR CONTENTS>NOTE>BATTERY .
   3. Using a tester, measure the resistance between Inverter with converter assembly connector and Hybrid vehicle control ECU assembly connector.

      Connector and terminal 

      (B606) No. 20 - (HV23) No. 24:

      (B606) No. 28 - (HV23) No. 20:

      Is the resistance less than 1 Ω?

      Yes: 

      Go to  7.

      No: 

      Repair or replace Wire harness between Hybrid vehicle control ECU assembly connector and Inverter with converter assembly connector.

7. CHECK Wire harness AND CONNECTOR (Inverter with converter assembly - Hybrid vehicle control ECU assembly) (SHORT TO GROUND OR LINE-TO-LINE SHORT)  .

   Using a tester, measure the resistance between terminals in Hybrid vehicle control ECU assembly connector, and between Hybrid vehicle control ECU assembly connector and chassis ground.

   Connector and terminal 

   (B606) No. 20 - (B606) No. 1 - 35:

   (B606) No. 20 - Chassis ground:

   (B606) No. 28 - (B606) No. 1 - 35:

   (B606) No. 28 - Chassis ground:

   Is the resistance 10 kΩ or more?

   Yes: 

   Go to  8.

   No: 

   Repair or replace Wire harness between Hybrid vehicle control ECU assembly connector and Inverter with converter assembly connector.

8. CHECK Hybrid vehicle control ECU assembly (INTERNAL RESISTANCE)  .
   1. Connect the connector (B606) of Hybrid vehicle control ECU assembly.
   2. Using a tester, measure the resistance between Hybrid vehicle control ECU assembly connector terminals. (With the connector connected)

      Connector and terminal 

      (B606) No. 20 - (B606) No. 28:

      Is the resistance 110 - 130 Ω?

      Yes: 

      Replace Inverter with converter assembly. Ref. to HYBRID ELECTRIC VEHICLE>INVERTER AND CONVERTER ASSEMBLY .

      No: 

      Replace Hybrid vehicle control ECU assembly. Ref. to HYBRID ELECTRIC VEHICLE>HYBRID POWERTRAIN CONTROL MODULE .

9. REPLACE FUSE (PCM FR)  .
   1. Replace F/B NO. 24 FUSE. Ref. to HYBRID ELECTRIC VEHICLE>RELAY AND FUSE .
   2. Turn to READY ON.
   3. Check that F/B NO. 24 FUSE is not blown out.

      Is the F/B NO. 24 FUSE OK?

      Yes: 

      Currently, it is normal.

      NOTE:

      If F/B NO. 24 FUSE is blown out after turning to READY ON, judge as aging deterioration of the fuse. 

      No: 

      Go to  10.

10. CHECK Wire harness AND CONNECTOR (Inverter with converter assembly - Relay and fuse box (F/B))  .
    1. Check that the Service plug is disconnected. Ref. to HYBRID ELECTRIC VEHICLE>SERVICE PLUG .
    2. Remove the F/B NO. 24 FUSE from the Relay and fuse box (F/B). Ref. to HYBRID ELECTRIC VEHICLE>RELAY AND FUSE .
    3. Disconnect Inverter with converter assembly connector (HV23).
    4. Using a tester, measure the resistance between terminals in Inverter with converter assembly connector, and between Inverter with converter assembly connector and chassis ground.

       Connector and terminal 

       (HV23) No. 1 - (HV23) No. 1 - 24:

       (HV23) No. 1 - Chassis ground:

       Is the resistance 10 kΩ or more?

       Yes: 

       Replace Inverter with converter assembly and F/B NO. 24 FUSE. Ref. to HYBRID ELECTRIC VEHICLE>INVERTER AND CONVERTER ASSEMBLY . Ref. to HYBRID ELECTRIC VEHICLE>RELAY AND FUSE .

       No: 

       Repair or replace the Wire harness between Inverter with converter assembly connector and F/B NO. 24 FUSE.