Circuit Description

Idle Speed Control (ISC) motor opens and closes throttle valve according to signals from PCM. When a condition occurs requiring a higher idle speed, PCM will send a signal to ISC motor which will extend plunger of ISC motor, which opens throttle plates to increase idle speed. PCM will reverse polarity to ISC motor causing throttle plates to close, thus decreasing idle speed when higher idle speed is no longer necessary. DTC P0505 will set when:

• Throttle valve feed back check indicates throttle valve movement is less than.244 degrees. This check will run 10 continuous times per drive cycle.
• ISC motor voltage check indicates no operation signal from PCM. This check will run 2 continuous times per drive cycle.