Idle-Up Circuit (Metro)

PCM monitors a signal from electrical load diode module. An electrical load will be indicated when heater blower motor, rear defogger or headlight/parking lights are turned on. PCM will adjust engine idle speed using Idle Speed Control (ISC) motor when an electrical load voltage signal is received. When electrical load voltage signal is removed, PCM will return engine to normal idle speed. To check electrical load idle-up circuit, see ELECTRICAL LOAD IDLE-UP CIRCUIT (METRO)  under CIRCUIT TESTS.

A/C compressor control module sends an idle-up signal to PCM when A/C compressor clutch is in operation. PCM will activate Idle Speed Control (ISC) motor. ISC motor opens throttle plate to control engine speed to prevent rough idle or stalling condition. To check A/C idle-up circuit, see A/C IDLE-UP CIRCUIT (METRO)  under CIRCUIT TESTS.