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Home >> Honda >> 1987 >> Civic DX, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Electronic Control System >> Testing >> Idle Control Solenoid Valve
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Idle Control Solenoid Valve

  1. Idle control solenoid valve is activated by commands from ECU. When solenoid valve opens, vacuum enters hose between air filter and solenoid valve. Idle speed increases for an period of time after starting engine and whenever electrical loads are turned on.
    NOTE: Vacuum will disappear when engine RPM is raised above 1500-1700 RPM.
  2. While solenoid valve is being activated, 9 volts or more should be available between Black (Black/Yellow on Prelude) terminal (A) and Light Green (Green/Black on Prelude) (B) of valve leads.
  3. On Prelude, disconnect wire harness from idle control solenoid valve. Disconnect vacuum hose No. 26 from air flow tube. Apply vacuum to hose. Vacuum should hold constant.
  4. Connect positive battery terminal to Black/Yellow terminal of control box and negative battery terminal to Green/Black terminal. Disconnect vacuum hose No. 28 from intake manifold. Apply vacuum to vacuum hose No. 26. Vacuum should not hold constant.
  5. On Civic CRX Si models, open control box lid and disconnect wiring harness from control box. Disconnect No. 10 vacuum hose from idle control solenoid valve. Connect vacuum gauge to hose and apply vacuum. Vacuum should hold constant.
  6. Connect battery positive terminal to control box connector Black terminal and negative terminal to Light Green terminal. Apply vacuum to hose. Vacuum should not hold constant. If vacuum holds constant, replace valve.
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