Circuit/System Testing

Operate the vehicle in 2nd gear. The engine should not stall when shifting into 2nd gear.
- Inspect and repair as necessary, the control valve body assembly for a stuck 3-4, 4-5 solenoid valve or a stuck U1 shift valve. Refer to the CONTROL VALVE BODY ASSEMBLY DISASSEMBLE .
Observe the scan tool Transmission OSS parameter while driving the vehicle. The reading should correspond to a known properly functioning OSS.
- If the OSS is malfunctioning, replace the Transmission Output Speed Sensor (OSS). Refer to the OUTPUT SPEED SENSOR REPLACEMENT .
Stop the vehicle, apply the parking brake, engine at idle, select P (park) using the Shift Control.
Observe the scan tool Transmission ISS parameter. The reading should be within 400-800 RPM.
- If the ISS parameter is not within the specified range, replace the Transmission Input Speed Sensor (ISS). Refer to the INPUT SPEED SENSOR REPLACEMENT .
Perform a line pressure test. refer to LINE PRESSURE CHECK .
Remove the control valve body cover. refer to CONTROL VALVE BODY COVER REMOVAL .
Inspect the inside of the control valve body cover for excessive sediment. There should not be excessive sediment.
- If excessive sediment is found, inspect and replace as necessary the Direct clutch, Low and reverse clutch, and 1 -2 reverse clutch. refer to FORWARD AND DIRECT CLUTCH ASSEMBLY ASSEMBLE , FRONT INTERNAL GEAR AND LOW AND REVERSE CLUTCH INSTALLATION , and 1-2 REVERSE CLUTCH ASSEMBLE .
Inspect the control valve body assembly for the following conditions. refer to CONTROL VALVE REAR BODY DISASSEMBLE and CONTROL VALVE BODY DISASSEMBLE - MIDDLE . The conditions should not be found.
- Stuck U1 shift valve
- Stuck M1 shift valve
- Stuck U2 shift valve
- Stuck neutral relay valve
- Stuck line pressure control solenoid valve assembly
  - If any of the above conditions are found, replace the valve body assembly. refer to CONTROL VALVE BODY REPLACEMENT .
Verify that the control valve body has been serviced within the past 3 months.
- If the control valve body has not been serviced, replace the control valve body assembly. refer to CONTROL VALVE BODY REPLACEMENT .
If all circuits and components test normal, replace the transmission.