LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 1988 >> Land Cruiser >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Computer Control System >> Component Testing >> Idle Speed Control (ISC) Valve
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Idle Speed Control (ISC) Valve

  1. Listen for "clicking" sound after engine is shut off. If no sound is heard, disconnect ISC valve connector.
  2. Note terminal identification. Using an ohmmeter, check resistance between designated terminals. See ISC VALVE RESISTANCE SPECIFICATIONS  table.
    ISC VALVE RESISTANCE SPECIFICATIONS

    Terminals Ohms
    B1 - S1 or S 10-30
    B2 - S2 or S4 10-30
  3. To check valve operation, apply battery voltage to terminal "B1" and terminal "B2". See Figure. Repeatedly ground terminals "S1", "S2", "S", "S4" and "S1" in sequence. Note that valve closes.
  4. Apply battery voltage to terminals "B1" and "B2". Repeatedly ground terminals "S4", "S", "S2", "S1" and "S4" in sequence. Note that valve opens. Replace valve if it failed to operate properly.
scientia non olet · About LEMON Manuals