Powertrain Control Module

WARNING: This page does not describe the selected car, but rather 36 other vehicles, including the 2002 Pontiac Firebird, 2002 Oldsmobile Bravada, 2002 GMC Yukon XL, 2002 GMC Yukon, and 2002 GMC Sonoma. However, it is still accessible from the selected car via links, so may be relevant.

The PCM is the control center of the vehicle that controls the following:

Fuel metering system.
Transmission shifting.
Ignition timing.
On-board diagnostics for powertrain functions.

For model specific PCM locations, see POWERTRAIN CONTROL MODULE under COMPONENT LOCATIONS.

The PCM supplies either 5 or 12 volts to power various sensors and switches. This is done through resistances in the PCM. The resistance is so high in value that a test light does not illuminate when connected to the circuit. In some cases, even an ordinary shop voltmeter does not give an accurate reading because the voltmeters resistance is too low. Therefore, a DVOM with a minimum of 10 megohms input impedance is required to ensure accurate voltage readings.