P0788

U341E AUTOMATIC TRANSAXLE: AUTOMATIC TRANSAXLE SYSTEM: P0787,P0788: Shift / Timing Solenoid Low (Shift Solenoid Valve ST)

DTC P0787 - Shift / Timing Solenoid Low (Shift Solenoid Valve ST)

DTC P0788 - Shift / Timing Solenoid High (Shift Solenoid Valve ST)

DESCRIPTION

Shift solenoid valve ST is switched ON-OFF by a signal from ECM so that let in or out timing of the 2nd brake is adjusted by operating the orifice control valve. Therefore, shift solenoid valve ST operates when letting in or out the reverse clutch.
If the shift solenoid valve ST is broken, the shift shock becomes big.






MONITOR DESCRIPTION

The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF". When there is an open or short circuit in any shift solenoid valve circuit, the ECM detects the problem, illuminates the MIL and stores the DTC. Illuminating the MIL, the ECM performs the fail-safe and turns the other shift solenoid valves in good condition "ON/OFF" (In case of an open or short circuit, the ECM stops sending current to the circuit.).

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

P0787: Range check (Low resistance)





P0788: Range check (High resistance)





TYPICAL MALFUNCTION THRESHOLDS

P0787: Range check (Low resistance)





P0788: Range check (High resistance)





COMPONENT OPERATING RANGE





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT TRANSMISSION WIRE (ST)




(a) Disconnect the transmission wire connector from the transaxle.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:






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




(a) Connect the transmission connector to the transaxle.
(b) Disconnect the connector from the ECM.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






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




(a) Remove the shift solenoid valve ST.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:





(c) Connect the positive (+) lead to the terminal of the solenoid connector, and the negative (-) lead to the solenoid body.
Standard:
The solenoid makes an operating sound.
NG -- REPLACE SHIFT SOLENOID VALVE ST
OK -- REPAIR OR REPLACE TRANSMISSION WIRE