1998 Nissan-Datsun Sentra BaseFACTORY OEM SERVICE PROCEDURE

Fast Idle Control Device (FICD) System Test: 240SX

  1. Start engine and warm to operating temperature. Check idle speed. See SPECIFICATIONS article. Adjust idle speed if necessary. See ADJUSTMENTS article. Turn A/C switch and blower fan switch on. Idle speed should increase. If idle speed does not increase, go to next step. If idle speed increases, system is functioning properly.
  2. Ensure A/C compressor functions normally. If compressor is not functioning, repair A/C system as necessary. If compressor is functioning, go to next step.
  3. Turn ignition off. Disconnect FICD solenoid sub-harness connector located above upper radiator hose engine inlet tube. Start engine and let it idle. Using DVOM, measure voltage between ground and FICD sub-harness connector terminal No. 3 (Blue/Red wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, repair open in Blue/Red wire between A/C relay and FICD solenoid sub-harness connector. See WIRING DIAGRAMS article. Also check A/C relay and Green/Black wire between A/C relay and fuse block.
  4. Turn ignition off. Disconnect FICD solenoid sub-harness connector. Check continuity between FICD solenoid sub-harness connector terminal No. 4 (Green wire) and ambient air temperature switch harness connector terminal No. 1 (Blue/White wire). Also check continuity between ground and ambient air temperature switch harness connector terminal No. 2 (Black wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, check and repair or replace appropriate wire. See WIRING DIAGRAMS article. Also check diode and ambient air temperature switch.
  5. Check FICD solenoid. See FAST IDLE CONTROL DEVICE (FICD) SOLENOID . If FICD solenoid is okay, check PCM and harness connector terminals for pushed-out, damaged, or corroded terminals. Repair or replace as necessary.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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