Code 46, (Upgraded Emissions) - Idle Speed Control Motor: Notes
Idle Speed Control (ISC) motor opens and closes the throttle valve according to signals from ECM. ECM will send a signal to ISC motor extending the plunger of the ISC motor, thus opening the throttle plates to increase idle speed when a condition arises which demands a higher idle speed. ECM will reverse the polarity to ISC motor causing throttle plates to close, thus decreasing idle speed when the higher idle speed is no longer necessary. Code 46 will set when the following conditions are met.
- If battery voltage is greater than 12 volts, idle switch is closed and change in throttle valve opening is less than .3 degrees after ECM has energized the ISC motor for more than .8 second.
- If throttle valve opening is sensed at less than 2.5 degrees.
- If ISC motor drive voltage is sensed twice when the signal is not fed from ECM.
- If throttle valve opening is not within 3 degrees of the target throttle valve opening under any of the following conditions.
- Battery voltage is greater than 12 volts.
- Idle switch is closed.
- 3 seconds since engine was started.
- During deceleration or idle.
- Electrical load, A/C or transaxle Drive range idle-up signal not inputted to ECM.NOTE: Test numbers refer to test numbers on diagnostic chart.
- Checks electrical load idle-up circuit.
- Checks for open in White/Blue wire.
- Checks for open in Gray/Black wire or for faulty ISC motor relay.
- Checks for open, short to ground or short to voltage in Green/Red, Gray or Gray/Yellow wires, or for faulty ISC motor.
- Checks for open, short to ground or short to voltage in Green/Red, Gray or Gray/Yellow wires, or for faulty ISC motor.
- Checks for open in Black/Green wire.
- Checks for open, short to ground or short to voltage in Light Green wire, or for faulty ECM.
- Checks for short to voltage in Light Green/Yellow wire, or for faulty ISC motor.
- Checks for open, short to ground or short to voltage in Light Green/Yellow wire, or faulty ISC motor or ECM.