DTC P0A78-121: Drive Motor "A" Inverter Performance [10/2014 - 10/2015]: 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 for DTCs.

   Result

   Result	Proceed to
   P0A78-121 is stored before any of the DTCs in the table below are stored.	A
   Any of the DTCs in the table below are stored before P0A78-121 is stored.	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, P3025-123, P3026-123, P3027-123	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 stored.
   • P0A78-121 may be stored due to a malfunction which also causes DTCs in the preceding table to be stored. 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.

Result: 

B 

GO TO DTC CHART (HYBRID BATTERY SYSTEM) 

(Refer to DIAGNOSTIC TROUBLE CODE CHART [10/2014 - 10/2015] )

Result: 

A 

See step  2

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 for DTCs.

   Result

   Result	Proceed to
   P0A78-121 only is output, or DTCs except the ones in the table below are also output.	A
   Any of the following DTCs including pending 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 stored due to a malfunction which also causes DTCs in the preceding table to be stored. 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.

Result: 

B 

GO TO DTC CHART (HYBRID CONTROL SYSTEM) 

(Refer to DIAGNOSTIC TROUBLE CODE CHART [10/2014 - 10/2015] )

Result: 

A 

See step  3

Refer to PROCEDURE - Step 4

Result: 

NG 

CONNECT SECURELY 

Result: 

OK 

See step  4

Refer to PROCEDURE - Step 3

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  5

Refer to PROCEDURE - Step 4

Result: 

NG 

See step  25

Result: 

OK 

See step  6

Refer to PROCEDURE - Step 5

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  7

Refer to PROCEDURE - Step 6

Result: 

NG 

See step  27

Result: 

OK 

See step  8

See step  9

Result: 

B 

REPLACE MALFUNCTIONING PARTS 

Result: 

C 

CONNECT SECURELY 

Result: 

A 

See step  9

See step  10

Result: 

B 

REPLACE MALFUNCTIONING PARTS 

Result: 

C 

CONNECT SECURELY 

Result: 

A 

See step  10

See step  11

Result: 

NG 

REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY 

(Refer to COMPONENTS [10/2014 - ] )

Result: 

OK 

See step  11

See step  12

Result: 

NG 

REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY 

(Refer to COMPONENTS [10/2014 - ] )

Result: 

OK 

See step  12

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 otherwise instructed because this may cause a malfunction.

2. Remove the connector cover assembly from the inverter with converter assembly.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

3. Check that the bolt for the No. 4 floor wire is tightened to the specified torque, the No. 4 floor wire is connected securely, and there are no contact problems.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Specified Condition

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

4. Disconnect the b1 inverter with converter assembly connector.
5. Check for arc marks at the bolt and terminals for the No. 4 floor 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. Reconnect the b1 inverter with converter assembly connector.
7. Install the connector cover assembly.

Result: 

B 

REPLACE MALFUNCTIONING PARTS 

Result: 

C 

CONNECT SECURELY 

Result: 

A 

See step  13

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 matter has not entered the connectors, and there is no evidence of contamination.

Result: 

NG 

REPLACE SERVICE PLUG GRIP 

(Refer to COMPONENTS [10/2014 - ] )

Result: 

OK 

See step  14

1. Remove the service plug grip.
2. Measure the resistance according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *1	Service Plug Grip

   Standard Resistance

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

3. Install the service plug grip.

Result: 

NG 

REPLACE SERVICE PLUG GRIP 

(Refer to COMPONENTS [10/2014 - ] )

Result: 

OK 

See step  15

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 otherwise instructed because this may cause a malfunction.

2. Remove the No. 4 hybrid battery shield panel (Refer to PROCEDURE - Step 8 ).
3. Check that the No. 4 floor wire connectors are connected securely, and there are no contact problems.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

4. Disconnect the b2 and b3 hybrid battery junction block assembly connectors.
5. Check for arc marks on the terminals of the No. 4 floor 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. Reconnect the b2 and b3 hybrid battery junction block assembly connectors.
7. Install the No. 4 hybrid battery shield panel.

Result: 

B 

REPLACE MALFUNCTIONING PARTS 

Result: 

C 

CONNECT SECURELY 

Result: 

A 

See step  16

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 otherwise instructed because this may cause a malfunction.

2. Remove the No. 4 hybrid battery shield panel (Refer to PROCEDURE - Step 8 ).
3. Disconnect the b2 and b3 hybrid battery junction block assembly connectors.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

4. Remove the connector cover assembly from the inverter with converter assembly.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

5. Disconnect the b1 inverter with converter assembly connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *1	Shield Ground
   *a	No. 4 Floor Wire (Inverter with Converter Assembly Side)
   *b	No. 4 Floor Wire (Hybrid Battery Junction Block Assembly Side)

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   b1-1 (CBI) - b2-1 (CBI) (Positive terminal)	Power switch off	Below 1 Ω
   b1-2 (CEI) - b3-1 (CEI) (Negative terminal)	Power switch off	Below 1 Ω

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	Condition	Specified Condition
   b2-1 (CBI) - Body ground and shield ground	Power switch off	10 MΩ or higher
   b3-1 (CEI) - Body ground and shield ground	Power switch off	10 MΩ or higher
   b2-1 (CBI) - b3-1 (CEI)	Power switch off	10 MΩ or higher

8. Reconnect the b2 and b3 hybrid battery junction block assembly connectors.
9. Reconnect the b1 inverter with converter assembly connector.
10. Install the connector cover assembly.
11. Install the No. 4 hybrid battery shield panel.

Result: 

NG 

REPLACE NO. 4 FLOOR WIRE 

(Refer to COMPONENTS [10/2014 - ] )

Result: 

OK 

See step  17

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 otherwise instructed because this may cause a malfunction.

2. Remove the hybrid battery junction block assembly (Refer to COMPONENTS [10/2014 - ] ).
3. Measure the resistance according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A-1 (+) - b2-1 (CBI)	Auxiliary battery voltage is not applied between terminals K23-1 (SMRB) and K23-2 (GND)	10 kΩ or higher
   A-1 (+) - b2-1 (CBI)	Auxiliary battery voltage is applied between terminals K23-1 (SMRB) and K23-2 (GND)	Below 1 Ω

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   K23-1 (SMRB) - K23-2 (GND)	-40 to 80°C (-40 to 176°F)	25.0 to 59.0 Ω

5. Install the hybrid battery junction block assembly.

Result: 

NG 

REPLACE HV BATTERY JUNCTION BLOCK ASSEMBLY 

(Refer to COMPONENTS [10/2014 - ] )

Result: 

OK 

See step  18

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 otherwise instructed because this may cause a malfunction.

2. Remove the hybrid battery junction block assembly (Refer to COMPONENTS [10/2014 - ] ).
3. Measure the resistance according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   i1-1 (-) - b3-1 (CEI)	Auxiliary battery voltage is not applied between terminals K23-3 (SMRG) and K23-2 (GND)	10 kΩ or higher
   i1-1 (-) - b3-1 (CEI)	Auxiliary battery voltage is applied between terminals K23-3 (SMRG) and K23-2 (GND)	Below 1 Ω

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   K23-3 (SMRG) - K23-2 (GND)	-40 to 80°C (-40 to 176°F)	25.0 to 59.0 Ω

5. Install the hybrid battery junction block assembly.

Result: 

NG 

REPLACE HV BATTERY JUNCTION BLOCK ASSEMBLY 

(Refer to COMPONENTS [10/2014 - ] )

Result: 

OK 

See step  19

See step  13

Result: 

NG 

See step  29

Result: 

OK 

See step  20

See step  14

Result: 

NG 

REPAIR OR REPLACE POWER SOURCE CIRCUIT 

Result: 

OK 

See step  21

See step  15

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  22

See step  16

Result: 

NG 

REPLACE POWER MANAGEMENT CONTROL ECU 

(Refer to COMPONENTS [10/2014 - 10/2015] )

Result: 

OK 

See step  23

Refer to PROCEDURE - Step 7

Result: 

NG 

CONNECT SECURELY 

Result: 

OK 

See step  24

Refer to PROCEDURE - Step 8

Result: 

OK 

REPLACE INVERTER WITH CONVERTER ASSEMBLY 

(Refer to COMPONENTS [10/2014 - ] )

Result: 

NG 

CONNECT SECURELY 

Refer to PROCEDURE - Step 9

Result: 

NG 

CONNECT SECURELY 

Result: 

OK 

See step  26

Refer to PROCEDURE - Step 10

Result: 

OK 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

NG 

REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY 

(Refer to COMPONENTS [10/2014 - ] )

Refer to PROCEDURE - Step 11

Result: 

NG 

CONNECT SECURELY 

Result: 

OK 

See step  28

Refer to PROCEDURE - Step 12

Result: 

OK 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

NG 

REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY 

(Refer to COMPONENTS [10/2014 - ] )

See step  23

Result: 

NG 

See step  31

Result: 

OK 

See step  30

(Refer to COMPONENTS [10/2014 - ] )

NEXT 

REPLACE FUSE (INV) 

NEXT 

REPLACE FUSE (INV)