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 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, 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
   P0A94-172, 442, 548, 549, 553, 554, 555, 556, 557, 547, 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
   P0C76-523	Hybrid Battery System Discharge Time Too Long
   P3004-803	High Voltage Power Resource

   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   24 

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   20 

OK: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

NG → See step   22 

OK: Go to next step 

C → CONNECT SECURELY 

B → REPLACE MALFUNCTIONING PARTS 

A: Go to next step 

C → CONNECT SECURELY 

B → REPLACE MALFUNCTIONING PARTS 

A: Go to next step 

NG → See step   25 

OK: Go to next step 

NG → See step   25 

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 service information because this may cause a malfunction.

2. Remove the connector cover from the inverter with converter assembly.
   Fig 1: Identifying N1 Connector Of The Inverter With Converter Assembly

   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.

   Specified Condition

   T=8.0 N*m {82 kgf*cm, 71 in.*lbf}

   NOTE:

   Make sure that the tightening torque of the bolts is between 6.4 and 9.6 N*m (65 and 98 kgf*cm, 57 and 85 in.*lbf).

4. Disconnect the frame wire from the high voltage connector of the inverter with converter assembly.
5. Check for arc marks at the terminal 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 connector cover.

C → CONNECT SECURELY 

B → REPLACE MALFUNCTIONING PARTS 

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   26 

OK: Go to next step 

1. Measure the resistance according to the value(s) in the table below.
   Fig 2: Identifying Service Plug Grip

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

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

   TEXT IN ILLUSTRATION
   
   

   *1	Service Plug Grip

NG → See step   26 

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 service information because this may cause a malfunction.

2. Check that the nuts for the frame wire are tightened to the specified torque, the frame wire is connected securely, and there are no contact problems.
   Fig 3: Identifying Connectors N4 & N3 Frame Wire Is Correctly Secure

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Specified Condition

   T=9.0 N*m {92 kgf*cm, 80 in.*lbf}

   NOTE:

   Make sure that the tightening torque of the bolts is between 7.2 and 10.8 N*m (73 and 110 kgf*cm, 64 and 96 in.*lbf).

3. Disconnect the frame wire from the hybrid battery junction block assembly.
4. Check for arc marks at the bolts 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

5. Connect the frame wire to the hybrid battery junction block assembly.

C → CONNECT SECURELY 

B → REPLACE MALFUNCTIONING PARTS 

A: 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 service information because this may cause a malfunction.

   Fig 4: Identifying Connectors N4 & N3 Frame Wire Is Correctly Secure

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Remove the 2 nuts and disconnect the frame wire from the hybrid battery junction block assembly.
3. Remove the bolt and disconnect the frame wire from the high voltage connector of the inverter with converter assembly.
   Fig 5: Identifying N1 Connector Of The Inverter With Converter Assembly

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. Measure the resistance according to the value(s) in the table below.
   Fig 6: Identifying N1 Inverter with Converter Assembly Side Connector & N4 And N3 Frame Wire Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Switch Condition	Specified Condition
   N4-1 (CBI) (high voltage +) - N1-1 (CBI) (high voltage +)	Power switch off	Below 1 Ω
   N3-1 (CEI) (high voltage -) - N1-2 (CEI) (high voltage -)	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)
   *3	Red Mark

5. Using a megohmmeter set to 500 V, measure the resistance according to the value(s) in the table below.
   Fig 7: Identifying N4 & N3 Frame Wire, Red Mark & Shielded Ground Wire

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   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
   N4-1 (CBI) - Body ground and shielded wire ground	Power switch off	10 MΩ or more
   N3-1 (CEI) - Body ground and shielded wire ground	Power switch off	10 MΩ or more
   N4-1 (CBI) (high voltage +) - N3-1 (CEI) (high voltage -)	Power switch off	10 MΩ or more

   TEXT IN ILLUSTRATION
   
   

   *1	Frame Wire (Hybrid Battery Junction Block Assembly Side)
   *2	Red Mark
   *3	Shielded Wire Ground

6. Connect the frame wire to the hybrid battery junction block assembly.
7. Connect the frame wire to the inverter with converter assembly.

NG → See step   27 

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 service information because this may cause a malfunction.

2. Remove the hybrid battery junction block assembly.
3. Measure the resistance according to the value(s) in the table below.
   Fig 8: Identifying N4, z11 & z16 Hybrid Battery Junction Block Assembly Connectors

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   z11-1 (+) - N4-1 (CBI)	Auxiliary battery voltage is not applied between terminals z16-3 (SMRB) and z16-2 (GND)	10 kΩ or higher
   z11-1 (+) - N4-1 (CBI)	Auxiliary battery voltage is applied between terminals z16-3 (SMRB) and z16-2 (GND)	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *1	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
   z16-3 (SMRB) - z16-2 (GND)	-31 to 176°F (-35 to 80°C)	18.8 to 32.1 Ω

5. Install the hybrid battery junction block assembly.

NG → See step   28 

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 service information because this may cause a malfunction.

2. Remove the hybrid battery junction block assembly.
3. Measure the resistance according to the value(s) in the table below.
   Fig 9: Identifying N3, z13 & z16 Hybrid Battery Junction Block Assembly Connectors

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   z13-1 (-) - N3-1 (CEI)	Auxiliary battery voltage is not applied between terminals z16-1 (SMRG) and z16-2 (GND)	10 kΩ or higher
   z13-1 (-) - N3-1 (CEI)	Auxiliary battery voltage is applied between terminals z16-1 (SMRG) and z16-2 (GND)	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *1	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
   z16-1 (SMRG) - z16-2 (GND)	-31 to 176°F (-35 to 80°C)	18.8 to 32.1 Ω

5. Install the hybrid battery junction block assembly.

NG → See step   28 

OK: Go to next step 

NG → CONNECT SECURELY 

OK: Go to next step 

NG → CONNECT SECURELY 

OK → See step   29 

NG → CONNECT SECURELY 

OK: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   25 

NG → CONNECT SECURELY 

OK: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   25