Circuit Description

Powertrain Control Module (PCM) receives an idle-up signal from diode module. This signal is present whenever one or more of the following systems is turned on or operated:

• Headlights or parking lights.
• Rear window defogger.
• Heater blower motor.

Idle Speed Control (ISC) motor will increase throttle valve opening and engine RPM will slightly increase to compensate for additional electrical load.