Dtc P0973 Shift Solenoid A Control Circuit Low (Shift Solenoid Valve S1)

Transmission. Lexus Gs430, Gs300. Uzs190 Grs190
A960E Automatic Transmission. Lexus Gs430, Gs300. Uzs190 Grs190

DESCRIPTION

MONITOR DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT TRANSMISSION WIRE (S1)

CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE - ECM)

INSPECT SHIFT SOLENOID VALVE S1

DTC P0973 Shift Solenoid "A" Control Circuit Low (Shift Solenoid Valve S1)

DTC P0974 Shift Solenoid "A" Control Circuit High (Shift Solenoid Valve S1)


DESCRIPTION

Shifting from 1st to 6th is performed in combination with "ON" and "OFF" operation of the shift solenoid valves SL1, SL2, S1, S2, S3, S4 and SR which is controlled by the ECM. If an open or short circuit occurs in either of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valve to allow the vehicle to be operated smoothly. (In case of an open or short circuit, the ECM stops sending current to the circuit.) Fail safe function (Click here).

DTC No.
DTC Detection Condition
Trouble Area
P0973
ECM detects short in solenoid valve S1 circuit 2 times when solenoid valve S1 is operated (1-trip detection logic)
  1. Short in shift solenoid valve S1 circuit
  2. Shift solenoid valve S1
  3. ECM
P0974
ECM detects open in solenoid valve S1 circuit 2 times when solenoid valve S1 is not operated (1-trip detection logic)
  1. Open in shift solenoid valve S1 circuit
  2. Shift solenoid valve S1
  3. ECM

MONITOR DESCRIPTION

These DTCs indicate an open or short in the shift solenoid valve S1 circuit. When there is an open or short circuit in any shift solenoid valve circuit, the ECM detects the problem and illuminates the MIL and stores the DTC. When the shift solenoid valve S1 is on, if resistance is 8 Ω or less, the ECM determines there is a short in the shift solenoid valve S1 circuit.
When the shift solenoid valve S1 is off, if resistance is 100 kΩ or more, the ECM determines there is an open in the shift solenoid valve S1 circuit (Click here).

WIRING DIAGRAM


Lexus Gs430, Gs300. Uzs190 Grs190.A960E Automatic Transmission.Electronic Controlled Automatic Transmission System. Dtc P0973 Shift Solenoid A Control Circuit Low (Shift Solenoid Valve S1)


INSPECTION PROCEDURE


HINT:
The shift solenoid valve S1 is turned on/off normally when the shift lever is in the D position:

ECM command gearshift
1st
2nd
3rd
4th
5th
6th
Shift solenoid valve S1
OFF
ON
ON
ON
ON
ON
1.INSPECT TRANSMISSION WIRE (S1)


    Lexus Gs430, Gs300. Uzs190 Grs190.A960E Automatic Transmission.Electronic Controlled Automatic Transmission System. Dtc P0973 Shift Solenoid A Control Circuit Low (Shift Solenoid Valve S1)

  1. Disconnect the transmission wire connector from the transmission.

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

    Resistance:
    Tester Connection
    		Specified Condition
    20°C (68°F)
    8 - Body ground
    		11 to 15 Ω


NG
Go to step 3
OK


2.CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE - ECM)


    Lexus Gs430, Gs300. Uzs190 Grs190.A960E Automatic Transmission.Electronic Controlled Automatic Transmission System. Dtc P0973 Shift Solenoid A Control Circuit Low (Shift Solenoid Valve S1)

  1. Connect the transmission connector to the transmission.

  1. Disconnect the connector from the ECM.

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

    Resistance:
    Tester Connection
    		Specified Condition
    20°C (68°F)
    E7 - 19 (S1) - Body ground
    		11 to 15 Ω


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE ECM

3.INSPECT SHIFT SOLENOID VALVE S1


    Lexus Gs430, Gs300. Uzs190 Grs190.A960E Automatic Transmission.Electronic Controlled Automatic Transmission System. Dtc P0973 Shift Solenoid A Control Circuit Low (Shift Solenoid Valve S1)

  1. Remove the shift solenoid valve S1.

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

    Resistance:
    Tester Connection
    		Specified Condition
    20°C (68°F)
    Solenoid Connector (S1) - Solenoid Body (S1)
    		11 to 15 Ω

  1. Connect positive (+) lead to the terminal of the solenoid connector, and the negative (-) lead to the solenoid body.

    OK:
    The solenoid makes an operating sound.


NG
REPLACE SHIFT SOLENOID VALVE S1
OK

REPAIR OR REPLACE TRANSMISSION WIRE