Idle Speed Control System: Notes
- Before idle speed/IAC duty is checked or adjusted, ensure all wires and vacuum hoses are connected securely, accelerator cable has free play, valve clearance and timing are set to specification and all accessories are turned off. Ensure transmission is in Park (A/T) or Neutral (M/T), battery voltage is 11 volts or greater and throttle valve moves smoothly.
- Allow engine to reach normal operating temperature. Connect tachometer. Using a jumper wire, connect monitor connector terminal "D" (ground) to terminal "B" (diagnostic switch). Connect duty meter between terminal "D" (ground) and terminal "F" (duty output). See Fig 1 .
- Ensure ISC duty varies in accordance with engine load. See the ISC DUTY SPECIFICATION table. Turn ignition off and allow engine to cool. Ensure ISC actuator moves when ignition is turned on. If plunger does not move and ISC duty are not within specification, see DTC P0505 in appropriate BASIC TESTING article. Since many computer-controlled and monitored components set a Diagnostic Trouble Code (DTC) if they malfunction, also perform procedures in appropriate TESTS W/CODES article.
ISC DUTY SPECIFICATION
| Engine Load | ISC Duty Increase Percentage |
|---|---|
| Electrical Load | About 3.5 |
| Radiator Fan | About 3.5 |
| A/C | About 10 |
NOTE:
DO NOT
remove ISC actuator from throttle body, it is adjusted by manufacturer.