GM Service Manual Online
For 1990-2009 cars only

Electronic Component Malfunctions

Component/System

Can Effect

This table gives some general information about electronic component malfunctions. Use this information to become familiar with possible conditions caused by transmission/vehicle electrical components. Refer to the Diagnosis Tables for more specific information.

Throttle Position (TP) Sensor

    • Shift Pattern (erratic)
    • Shift quality (firm or soft)
    • Engine (rough)

Automatic Transmission Output Shaft Speed (AT OSS) Sensor

    • Shift Pattern (erratic)
    • TCC solenoid valve apply (at wrong time)
    • Shift quality (harsh or soft)

Transmission Fluid Pressure (TFP) Manual Valve Position Switch

    • TCC solenoid valve apply (no apply if diagnostic code is set)
    • Shift pattern (no fourth gear in hot mode)
    • Shift quality (harsh)
    • Line pressure (high)
    • Manual downshift (erratic)

Automatic Transmission Fluid Temperature (TFT) Sensor

    • TCC solenoid valve control (On or Off)
    • Shift quality (harsh or soft)

Engine Coolant Temperature (ECT) Sensor

    • TCC solenoid valve control (no apply)
    • Shift quality (harsh)

Shift Solenoid valves

Gear application (wrong gear, only two gears, no shift)

Brake Switch

    • TCC apply (no apply)
    • No 4th gear if in hot mode

System Voltage

    • Line pressure (high)
    • Gear application (third gear only)
    • TCC control (no apply)
    • No 4th gear if in hot mode)

3-2 Control Shift Solenoid Valve Assembly

    • Gear application (third gear only)
    • 3-2 Downshifts (flare or tie-up)

Pressure Control Solenoid

    • Line pressure (high or low)
    • Shift quality (harsh or soft)

TCC Sol Valve

    • TCC solenoid valve apply (no apply)
    • No 4th gear if in hot mode

Cruise Control

Delays 3-4 upshift and TCC apply during heavy throttle

Acceleration Slip Regulation (ASR)

Downshifts