P0974

U340E AUTOMATIC TRANSAXLE: AUTOMATIC TRANSAXLE SYSTEM: P0973: Shift Solenoid "A" Control Circuit Low (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 4th is performed in combination with the ON and OFF operations of shift solenoid valves S1 and S2 which are 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 driven smoothly.
(If an open or short circuit occurs, the ECM stops sending currents to the affected circuit.)
Fail-safe function Fail-Safe Chart.






MONITOR DESCRIPTION

The ECM commands gearshift by turning the shift solenoid valves ON/OFF. When there is an open or short circuit in the shift solenoid valve S1 circuit, the ECM detects the problem and the MIL comes on. Illuminating the MIL, the ECM performs the fail-safe and turns the other functioning shift solenoid valve ON/OFF.
(If an open or short circuit occurs, the ECM stops sending currents to the affected circuit.)

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

P0973: Range check (Low resistance)





P0974: Range check (High resistance)





TYPICAL MALFUNCTION THRESHOLDS

P0973: Range check (Low resistance)





P0974: Range check (High resistance)





COMPONENT OPERATING RANGE





WIRING DIAGRAM





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





PROCEDURE

1. INSPECT TRANSMISSION WIRE (SHIFT SOLENOID VALVE S1)




(a) Disconnect the transmission wire connector from the transaxle.
(b) Measure the resistance.
Standard resistance:






NG -- INSPECT SHIFT SOLENOID VALVE S1
OK -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE - ECM)




(a) Connect the transmission connector to the transaxle.
(b) Disconnect the ECM connector.
(c) Measure the resistance.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
3. INSPECT SHIFT SOLENOID VALVE S1




(a) Remove shift solenoid valve S1.
(b) Measure the resistance.
Standard resistance:





(c) Connect the positive (+) lead to the terminal of the solenoid connector and the negative (-) lead to the solenoid body to check the solenoid valve operation.
OK:
The solenoid makes operating sounds.
NG -- REPLACE SHIFT SOLENOID VALVE S1
OK -- REPAIR OR REPLACE TRANSMISSION WIRE