P0A78-128

L110 HYBRID VEHICLE CONTROL: HYBRID CONTROL SYSTEM: P0A78-128: Drive Motor "A" Inverter Performance

DTC P0A78-128 - Drive Motor "A" Inverter Performance

DESCRIPTION

For a description of the inverter, P0A78-266.
If an abnormal amount of current flows through the motor inverter, the MG ECU detects it and sends a signal to inform the hybrid vehicle control ECU of the malfunction.

INSPECTION PROCEDURE
CAUTION:
- Before inspecting the high-voltage system or disconnecting the low voltage connector of the inverter with converter assembly, take safety precautions such as wearing insulated gloves and removing the service plug grip to prevent electrical shocks. After removing the service plug grip, put it in your pocket to prevent other technicians from accidentally reconnecting it while you are working on the high-voltage system.
- After disconnecting the service plug grip, wait for at least 10 minutes before touching any of the high-voltage connectors or terminals. After waiting, check the voltage at the inspection point in the inverter with converter assembly. The voltage should be 0 V before beginning work.
HINT: Waiting for at least 10 minutes is required to discharge the high-voltage capacitor inside the inverter with converter assembly.

PROCEDURE

1. CHECK DTC OUTPUT (HV)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Select the following menu items: Powertrain / Hybrid Control / Trouble Codes.
(d) Check if DTCs are output.
Result:

HINT: P0A78-128 may be set due to a malfunction which also causes DTCs in the table above to be set. In this case, first troubleshoot the output DTCs in the table above. Then, perform a test to attempt to reproduce the problems, and check that no DTCs are output.

YES -- GO TO DTC CHART
NO -- Continue to next step.
2. CHECK CONNECTOR CONNECTION CONDITION (INVERTER WITH CONVERTER ASSEMBLY CONNECTOR)

(a) Check the connection of the low voltage connector of the inverter with converter assembly.
Result:
The connector is connected securely and there are no contact problems.
NG -- CONNECT SECURELY
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - MOTOR RESOLVER)
CAUTION: Be sure to wear insulated gloves.
(a) Turn the power switch off and remove the service plug grip L110 Hybrid Vehicle Control System.
NOTE: After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the repair procedure because this may cause a malfunction.

(b) Disconnect connector A60 from the inverter with converter assembly.
(c) Turn the power switch on (IG).
(d) Measure the voltage according to the value(s) in the table below.
Standard voltage:

NOTE: Turning the power switch on (IG) with the low voltage connector of the inverter with converter assembly disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. CHECK MOTOR RESOLVER

(a) Turn the power switch off.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):

NG -- CHECK CONNECTOR CONNECTION CONDITION (MOTOR RESOLVER CONNECTOR)
OK -- Continue to next step.
5. CHECK INVERTER WITH CONVERTER ASSEMBLY (MOTOR CABLE CONNECTION CONDITION)
CAUTION: Be sure to wear insulated gloves.
(a) Check that the service plug grip is not installed.

(b) Check that the bolts for the motor cable are tightened to the specified torque.
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).

Torque: 8.0 Nm (82 kgf-cm, 71 in-lbf)
NG -- TIGHTEN TO SPECIFIED TORQUE
OK -- Continue to next step.
6. CHECK HYBRID VEHICLE TRANSMISSION ASSEMBLY (MG2)
CAUTION: Be sure to wear insulated gloves.
(a) Check that the service plug grip is not installed.
(b) Disconnect the generator cable and motor cable from the inverter with converter assembly Components.

(c) Using a milliohmmeter, measure the resistance according to the value(s) in the table below. (Check MG2 for an interphase short.)
HINT: If the MG2 temperature is high, the resistance varies greatly. Therefore, measure the resistance at least 8 hours after the vehicle is stopped.

Standard resistance:

To correct the variation of the measured resistance due to temperature, use the following formula to calculate the resistance at 20°C (68° F).
R20 = Rt / {1 + 0.00393 X (T - 20)}
The calculation is based on the following:
R20: Resistance at 20°C (mOhms)
Rt: Measured resistance (mOhms)
T: Temperature when the resistance is measured (° C)
(d) 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:

NG -- CHECK HYBRID VEHICLE TRANSMISSION ASSEMBLY (MOTOR CABLE CONNECTION CONDITION)
OK -- REPLACE INVERTER WITH CONVERTER ASSEMBLY
7. CHECK CONNECTOR CONNECTION CONDITION (MOTOR RESOLVER CONNECTOR)

(a) Check the connection of the motor resolver connector.
Result:
The connector is connected securely and there are no contact problems.
NG -- CONNECT SECURELY
OK -- Continue to next step.
8. CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - MOTOR RESOLVER)

(a) Disconnect connector E88 from the motor resolver.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):

Standard resistance (Check for short):

HINT: The motor resolver is not available separately. If it requires replacement, replace the hybrid vehicle transmission assembly.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE HYBRID VEHICLE TRANSMISSION ASSEMBLY
9. CHECK HYBRID VEHICLE TRANSMISSION ASSEMBLY (MOTOR CABLE CONNECTION CONDITION)

(a) Remove the hybrid vehicle transmission assembly Components.
(b) Check that the bolts for the motor cable are tightened to the specified torque.
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).

Torque: 8.0 Nm (82 kgf-cm, 71 in-lbf)
NG -- TIGHTEN TO SPECIFIED TORQUE
OK -- Continue to next step.
10. CHECK MOTOR CABLE
(a) Remove the motor cable from the transmission Components.

(b) 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:

(c) Measure the resistance of each conductor in the motor cable according to the value(s) in the table below.
Standard resistance:

NG -- REPLACE MOTOR CABLE
OK -- REPLACE HYBRID VEHICLE TRANSMISSION ASSEMBLY