GM Service Manual Online
For 1990-2009 cars only

Caution: 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 sensor input could cause erratic shift patterns, poor shift quality, or poor TCC function.

Automatic Transaxle Output (Shaft) Speed Sensor

Provides vehicle speed data to the TCM for determining shift patterns, TCC apply/release, and gear ratio calculations.

An incorrect throttle sensor input could cause erratic shift patterns, poor shift quality, or poor TCC function.

Automatic Transaxle Input (Shaft) Speed Sensor

Provides transaxle input speed data to the TCM for determining shift patterns, 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 for the TCM.

The TCM uses engine speed information for controlling wide open throttle shifts and the TCC/pulse width modulation (PWM) solenoid duty cycle.

Stoplamp Switch

Provides brake apply information to the TCM for controlling TCC apply and release.

An incorrect stoplamp 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.

An incorrect transaxle temperature sensor input could cause altered shift patterns, poor shift quality, and incorrect TCC apply.