The ECM processes information from the input signals and sends appropriate voltage control signals to the following engine controls. For theory and operation of specific output components, refer to system indicated in brackets:

Air Injection Reaction Solenoid (Spectrum - Emissions)
Automatic Transmission Lock-up Relay (Tracker - Transmission Control)
Bowl Vent Solenoid (Spectrum - Emissions)
CHECK ENGINE" Light (Self-Diagnostics)
Circuit Opening Relay (Prizm - Fuel Delivery)
Control Relay (Tracker - ECM and Fuel Delivery)
Early Fuel Evaporation Relay and Heater (Spectrum - Emissions)
EFI Main Relay (Prizm - ECM, Fuel Delivery)
EGR Solenoid (Metro, Prizm and Tracker - Emissions)
Fuel-Cut Relay and Solenoid (Spectrum - Fuel Control)
Fuel-Cut System (Tracker and Prizm - Fuel Control)
Fuel Pump Relay (Metro - Fuel Delivery)
Idle Speed Control (ISC) Solenoid (Tracker, Prizm, and Metro - Idle Speed)
Injector(s) (Fuel Control)
Mixture Control Solenoid (Spectrum - Fuel Control)
PTC Heater Relay (Tracker - Emissions)
Purge Solenoid (Metro - Emissions)
Throttle Opener Controller and Idle-Up Solenoid (Spectrum, Tracker - Idle Speed)
Transmission Converter Clutch Relay (Tracker - Transmission Control)
Vacuum Switching Valve (Prizm - Idle Speed)

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Output Signals

Use the Manual With the Right Hardware

When to See a Mechanic