DTC P2798-858: Auxiliary Transmission Fluid Pump Control Circuit Low: Procedure

1. Connect an oscilloscope to the hybrid vehicle control ECU terminals specified in the table below, and measure the waveform.
   Fig 1: Identifying A75 And A74 Connector Terminals

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   Item	Contents
   Terminal	A74-33 (OPST) - A75-7(E1)
   Equipment Setting	5 V/DIV., 5 ms./DIV.
   Condition	Power switch on (IG)

   Result

   Result	Proceed to
   Waveform is flat, and is stuck on the GND side.	A
   Normal	B

B → See step   7 

A: Go to next step 

1. Check the connections of the oil pump motor controller connectors.
   Fig 2: Locating Oil Pump Motor Controller Connectors

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   OK

   The connectors are connected securely and there are no contact problems.

   HINT: 

   For connector A, when connecting it, insert it with the locking lever in the raised position. Rotate the lever downward and make sure that the connector is pulled into its socket. When the locking lever is in its fully closed position, a click will be heard as its locking claws engage. After the click is heard, pull up on the connector to confirm that it is properly connected.

NG → CONNECT SECURELY 

OK: Go to next step 

1. Check the connections of the hybrid vehicle control ECU connectors.

   OK

   The connectors are connected securely and there are no contact problems.

NG → CONNECT SECURELY 

OK: Go to next step 

1. Turn the power switch off.
2. Disconnect connector A78 from the oil pump motor controller.
   Fig 3: Identifying A78 Connector Terminals

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3. Turn the power switch on (IG).
4. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   A78-7 (OPST) - Body ground	Power switch on (IG)	7 to 12 V

   NOTE:

   Turning the power switch on (IG) with the oil pump motor controller connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

NG → See step   6 

OK: Go to next step 

1. Turn the power switch off.
   Fig 4: Identifying A78 Connector Terminal (OPST)

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

   Standard resistance

   Tester Connection	Switch Condition	Specified Condition
   A78-7 (OPST) - Body ground	Power switch off	10 kΩ or higher

NG → See step   9 

OK → See step   8 

1. Turn the power switch off.
   Fig 5: Disconnecting Connector A74 From Hybrid Vehicle Control ECU

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect connector A74 from the hybrid vehicle control ECU.
3. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Switch Condition	Specified Condition
   A74-33 (OPST) - Body ground and other terminals	Power switch off	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   8 

1. Check for intermittent problems. Refer to CHECK FOR INTERMITTENT PROBLEMS .

NG → REPAIR OR REPLACE MALFUNCTIONING PARTS, COMPONENT AND AREA 

OK → See step   9