GM Service Manual Online
For 1990-2009 cars only

Notice: Lack of basic knowledge of this powertrain when performing diagnostic procedures could result in incorrect diagnostic performance or damage to powertrain components. Do not attempt to diagnose a powertrain problem without this basic knowledge.

Throttle Position Sensor

    • Provides throttle position data to the transmission control module (TCM) for determining shift patterns and torque converter clutch (TCC) apply/release.
    • An incorrect throttle position (TP) sensor input could causes erratic or shift pattern, poor shift quality, or TCC function.

Automatic Transaxle Output (Shaft) Speed Sensor

    • Provides vehicle speed data to the TCM for determining shift patterns and TCC apply/release and gear ratio calculations.
    • An incorrect throttle position sensor input could cause erratic or shift pattern, poor shift quality, or TCC function.

Automatic Transaxle Input (Shaft) Speed Sensor

Provides transaxle input speed data to the TCM for determining shift patterns and TCC apply/release and gear ratio.

Engine Coolant Temperature Sensor

    • Provides coolant temperature data to the TCM for determining initial TCC engagement.
    • An incorrect engine coolant temperature sensor input could cause an incorrect initial TCC apply.

Engine Speed

    • The ignition module provides engine speed data to the TCM.
    • The TCM uses engine speed information for controlling wide open throttle (WOT) shifts and the TCC pulse width modulation (PWM) solenoid duty cycle.

Stop Lamp Switch

    • Provides brake apply information to the TCM for controlling TCC apply and release.
    • An incorrect TCC stop lamp switch input could cause an incorrect TCC apply or release.

Transaxle Fluid Temperature (TFT) Sensor

    • Provides transaxle fluid temperature information to the TCM for determining alternate shift patterns and TCC apply during high temperature conditions hot mode operation.
    • An incorrect transaxle temperature sensor input could cause altered shift patterns, poor shift quality, and incorrect TCC apply.