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 procedure.
Observe the scan tool Transmission OSS parameter. 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 procedure.
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 procedure.
Firmly apply the brake, select D (drive) using the Shift Control.
Observe the scan tool TCC Slip Speed. The reading should be within 0-100 RPM.
- If the TCC Slip Speed is not within the specified range:
- Ignition ON, engine OFF, command shift solenoid 1 ON and OFF with a scan tool. The solenoid should click when commanded ON.
  - If the solenoid does not click, replace the 1st shift solenoid valve assembly. Refer to CONTROL VALVE BODY ASSEMBLY DISASSEMBLE .
- Command shift solenoid 3 ON and OFF with a scan tool. The solenoid should click when commanded ON.
  - If the solenoid does not click, replace the 1-2, 2-3, reverse shift solenoid valve assembly. Refer to CONTROL VALVE BODY ASSEMBLY DISASSEMBLE .
- Perform a line pressure test. Refer to LINE PRESSURE CHECK procedure.
- Remove the control valve body cover. Refer to CONTROL VALVE BODY COVER REMOVAL procedure.
- 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 low clutch sprag, forward clutch, and 1-2, reverse clutch. Refer to FRONT INTERNAL GEAR AND OVERRUN CLUTCH ASSEMBLE , FORWARD AND DIRECT CLUTCH ASSEMBLY ASSEMBLE and 1-2 Reverse Clutch Assemble procedures.
- Inspect the control valve body assembly for the following conditions. The conditions should not be found.
  - Stuck U1 shift valve
  - Stuck M1 shift valve
  - Stuck U2 shift valve
  - Stuck line pressure control solenoid valve assembly
  - Stuck neutral relay valve
    refer to CONTROL VALVE REAR BODY DISASSEMBLE and MIDDLE CONTROL VALVE BODY DISASSEMBLE .
    - If any of the above conditions are found, replace the valve body assembly. Refer to CONTROL VALVE BODY REPLACEMENT procedure.
- 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 procedure.
- If all circuits and components test normal, replace the transmission.
If all circuits and components test normal, replace the transmission.