DTC P0A78-121: Drive Motor "A" Inverter Performance: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.
4. Check if DTCs are output.

   Result

   Result	Proceed to
   P0A78-121 is set before any of the DTCs in the table below are set.	A
   Any of the DTCs in the table below are set before P0A78-121 is set.	B

   DTC No.	Relevant Diagnosis
   P0A9C-123	Hybrid Battery Temperature Sensor "A" Range / Performance
   P0A9D-123	Hybrid Battery Temperature Sensor "A" Circuit Low
   P0A9E-123	Hybrid Battery Temperature Sensor "A" Circuit High
   P0AC0-123	Hybrid Battery Pack Current Sensor Circuit Range / Performance
   P0AC1-123	Hybrid Battery Pack Current Sensor Circuit Low
   P0AC2-123	Hybrid Battery Pack Current Sensor Circuit High
   P0AC6-123	Hybrid Battery Temperature Sensor "B" Range/Performance
   P0AC7-123	Hybrid Battery Temperature Sensor "B" Circuit Low
   P0AC8-123	Hybrid Battery Temperature Sensor "B" Circuit High
   P0ACB-123	Hybrid Battery Temperature Sensor "C" Range / Performance
   P0ACC-123	Hybrid Battery Temperature Sensor "C" Circuit Low
   P0ACD-123	Hybrid Battery Temperature Sensor "C" Circuit High
   P0AFC-123	Hybrid Battery Pack Sensor Module
   P3011-123, P3012-123, P3013-123, P3014-123, P3015-123, P3016-123, P3017-123, P3018-123, P3019-123, P3020-123, P3021-123, P3022-123, P3023-123, P3024-123	Battery Block # Becomes Weak
   P3065-123	Hybrid Battery Temperature Sensor Range/Performance Stuck "A"
   P308A-123	Hybrid Battery Voltage Sensor All Circuits Low

   HINT: 

   • Refer to the Freeze Frame data to determine the order in which the DTCs were set.
   • P0A78-121 may be set due to a malfunction which also causes DTCs in the preceding table to be set. In this case, first troubleshoot the output DTCs in the preceding table. Then, perform a test to attempt to reproduce the problems, and check that no DTCs are output.
5. Turn the power switch off.

B → See step   42 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.
4. Check if DTCs are output.

   Result

   Result	Proceed to
   P0A78-121 only is output.	A
   Any of the following DTCs are also output.	B

   DTC No.	Relevant Diagnosis
   P0A1A (all INF codes)*1	Generator Control Module
   P0A1B (all INF codes)*1	Drive Motor "A" Control Module
   P0A1D (all INF codes)*1	Hybrid Powertrain Control Module
   P0A3F-243	Drive Motor "A" Position Sensor Circuit
   P0A40-500	Drive Motor "A" Position Sensor Circuit Range/Performance
   P0A41-245	Drive Motor "A" Position Sensor Circuit Low
   P0A4B-253	Generator Position Sensor Circuit
   P0A4C-513	Generator Position Sensor Circuit Range/Performance
   P0A4D-255	Generator Position Sensor Circuit Low
   P0A60 (all INF codes)*1	Drive Motor "A" Phase V Current
   P0A63 (all INF codes)*1	Drive Motor "A" Phase W Current
   P0A72 (all INF codes)*1	Generator Phase V Current
   P0A75 (all INF codes)*1	Generator Phase W Current
   P0A78-113, 128, 266, 267, 279, 284, 286, 287, 306, 503, 504, 505, 506, 565, 586, 806, 807, 808	Drive Motor "A" Inverter Performance
   P0A7A-122, 130, 322, 324, 325, 344, 517, 518, 809, 810, 811	Generator Inverter Performance
   P0A90-509	Drive Motor "A" Performance
   P0A92-521	Hybrid Generator Performance
   P0A93-346	Inverter Cooling System Performance
   P0A94-172, 442, 547, 548, 549, 553, 554, 555, 556, 557, 585, 587, 589, 590	DC/DC Converter Performance
   P0ADB-227	Hybrid Battery Positive Contactor Control Circuit Low
   P0ADC-226	Hybrid Battery Positive Contactor Control Circuit High
   P0ADF-229	Hybrid Battery Negative Contactor Control Circuit Low
   P0AE0-228	Hybrid Battery Negative Contactor Control Circuit High
   P0C73-776	Motor Electronics Coolant Pump "A" Control Performance
   P0C76-523	Hybrid Battery System Discharge Time Too Long
   P3004-803	High Voltage Power Resource
   P314A-828	Inverter Coolant Pump Speed Signal

   HINT: 

   • *1: If any INF codes are output for this DTC, refer to the corresponding diagnostic procedure.
   • P0A78-121 may be set due to a malfunction which also causes DTCs in the preceding table to be set. In this case, first troubleshoot the output DTCs in the preceding table. Then, perform a test to attempt to reproduce the problems, and check that no DTCs are output.
5. Turn the power switch off.

B → See step   35 

A: Go to next step 

NG → CONNECT SECURELY 

OK: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

NG → See step   24 

OK: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

NG → See step   26 

OK: Go to next step 

B → REPLACE MALFUNCTIONING PARTS 

C → CONNECT SECURELY 

A: Go to next step 

B → REPLACE MALFUNCTIONING PARTS 

C → CONNECT SECURELY 

A: Go to next step 

NG → See step   31 

OK: Go to next step 

NG → See step   33 

OK: Go to next step 

1. Check that the service plug grip is not installed.
   NOTE:

   After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the repair information because this may cause a malfunction.

2. Remove the inverter cover from the inverter with converter assembly.
   Fig 1: Identifying Inverter With Converter Assembly, Inverter Cover & Fasteners

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Check that the bolts for the frame wire are tightened to the specified torque, the frame wire is connected securely, and there are no contact problems.
   Fig 2: Identifying Frame Wire & Bolts

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Specified Condition

   Bolt A 

   8.0 N*m (82 kgf*cm, 71 in.*lbf)

   Bolt B 

   9.2 N*m (94 kgf*cm, 81 ft.*lbf)

   NOTE:

   • Make sure that the tightening torque of the bolt A is between 6.4 and 9.6 N*m (65 and 98 kgf*cm, 57 and 85 in.*lbf).
   • Make sure that the tightening torque of the bolt B is between 6.4 and 12 N*m (65 and 122 kgf*cm, 57 and 106 in.*lbf).
4. Disconnect the frame wire from the inverter with converter assembly.
5. Check for arc marks at the bolts and terminals for the frame wire.

   Result

   Result		Proceed to
   The terminals are connected securely and there are no contact problems.	There are no arc marks.	A
   The terminals are not connected securely and there is a contact problem.	There are arc marks.	B
   The terminals are not connected securely and there is a contact problem.	There are no arc marks.	C
   The terminals are connected securely and there are no contact problems.	There are arc marks.	B

6. Connect the frame wire to the inverter with converter assembly.
7. Install the inverter cover.

B → REPLACE MALFUNCTIONING PARTS 

C → CONNECT SECURELY 

A: Go to next step 

1. Visually check the connection of the service plug grip to the HV battery. Remove the service plug grip and check for contamination.

   OK

   Dirt or foreign objects have not entered the connection, and there is no evidence of contamination.

NG → See step   38 

OK: Go to next step 

1. Measure the resistance according to the value(s) in the table below.
   Fig 3: Inspecting Service Plug Grip

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   Service plug grip terminals	Always	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *1	Service plug grip

NG → See step   38 

OK: Go to next step 

1. Check that the service plug grip is not installed.
   NOTE:

   After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the repair information because this may cause a malfunction.

2. Remove the upper hybrid battery cover sub-assembly. Refer to REMOVAL - Step 19 .
3. Disconnect the frame wire from the hybrid battery junction block assembly.
   Fig 4: Identifying Frame Wire & Hybrid Battery Junction Block Assembly

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TEXT IN ILLUSTRATION
   
   

   *a	Frame Wire Connection Condition (Hybrid Battery Junction Block Assembly)

4. Remove the inverter cover from the inverter with converter assembly.
   Fig 5: Identifying Inverter With Converter Assembly, Inverter Cover & Fasteners

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
5. Disconnect the frame wire from the inverter with converter assembly.
   Fig 6: Identifying Frame Wire & Fasteners

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
6. Measure the resistance according to the value(s) in the table below.
   Fig 7: Measuring Resistance Of Frame Wire With T1 Connector End View

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Switch Condition	Specified Condition
   T4-1 (CBI) - T1-2 (CBI) (Positive terminal)	Power switch off	Below 1 Ω
   T3-1 (CEI) - T1-1 (CEI) (Negative terminal)	Power switch off	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *1	Frame Wire (Inverter with Converter Assembly Side)
   *2	Frame Wire (Hybrid Battery Junction Block Assembly Side)

7. Using a megohmmeter set to 500 V, measure the resistance according to the value(s) in the table below.
   NOTE:

   Be sure to set the megohmmeter to 500 V when performing this test. Using a setting higher than 500 V can result in damage to the component being inspected.

   Standard Resistance

   Tester Connection	Switch Condition	Specified Condition
   T4-1 (CBI) - Body ground and shielded ground	Power switch off	10 MΩ or higher
   T3-1 (CEI) - Body ground and shielded ground	Power switch off	10 MΩor higher
   T4-1 (CBI) - T3-1 (CEI)	Power switch off	10 MΩ or higher

8. Connect the frame wire to the hybrid battery junction block assembly.
9. Connect the frame wire to the inverter with converter assembly.
10. Install the inverter cover.
11. Install the upper hybrid battery cover sub-assembly.

NG → See step   37 

OK: Go to next step 

1. Check that the service plug grip is not installed.
   NOTE:

   After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the repair information because this may cause a malfunction.

2. Remove the hybrid battery junction block assembly. Refer to COMPONENTS .
3. Measure the resistance according to the value(s) in the table below.
   Fig 8: Inspecting Hybrid Battery Junction Block Assembly With Connector End View

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   h2-1 (+) - T4-1 (CBI)	Auxiliary battery voltage is not applied between terminals c3-4 (SMRB) and c3-2 (GND)	10 kΩ or higher
   h2-1 (+) - T4-1 (CBI)	Auxiliary battery voltage is applied between terminals c3-4 (SMRB) and c3-2 (GND)	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *a	Component without harness connected (Hybrid Battery Junction Block Assembly)

4. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   c3-4 (SMRB) - c3-2 (GND)	-40 to 80°C (-40 to 176°F)	19.0 to 35.5 Ω

5. Install the hybrid battery junction block assembly.

NG → See step   39 

OK: Go to next step 

1. Check that the service plug grip is not installed.
   NOTE:

   After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the repair information because this may cause a malfunction.

2. Remove the hybrid battery junction block assembly. Refer to COMPONENTS .
3. Measure the resistance according to the value(s) in the table below.
   Fig 9: Measuring The Resistance Of The SMRG Circuit

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   k2-1 (-) - T3-1 (CEI)	Auxiliary battery voltage is not applied between terminals c3-1 (SMRG) and c3-2 (GND)	10 kΩ or higher
   k2-1 (-) - T3-1 (CEI)	Auxiliary battery voltage is applied between terminals c3-1 (SMRG) and c3-2 (GND)	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *a	Component without harness connected (Hybrid Battery Junction Block Assembly)

4. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   c3-1 (SMRG) - c3-2 (GND)	-40 to 80°C (-40 to 176°F)	19.0 to 35.5 Ω

5. Install the hybrid battery junction block assembly.

NG → See step   39 

OK: Go to next step 

NG → See step   28 

OK: Go to next step 

NG → REPAIR OR REPLACE POWER SOURCE CIRCUIT 

OK: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

NG → See step   40 

OK: Go to next step 

NG → CONNECT SECURELY 

OK: Go to next step 

NG → CONNECT SECURELY 

OK → See step   41 

NG → CONNECT SECURELY 

OK: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   36 

NG → CONNECT SECURELY 

OK: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   36 

NG → See step   30 

OK: Go to next step 

Refer to COMPONENTS

NEXT → REPLACE FUSE (PCU) 

NEXT → REPLACE FUSE (PCU) 

B → REPLACE MALFUNCTIONING PARTS 

C → CONNECT SECURELY 

A: Go to next step 

NG → See step   43 

OK → See step   36 

B → REPLACE MALFUNCTIONING PARTS 

C → CONNECT SECURELY 

A: Go to next step 

NG → See step   44 

OK → See step   36