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Home >> Mercedes Benz >> 1981 >> 280CE >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Air Injection System >> Testing >> 380 Models >> System Check
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System Check

  1. Start engine and warm to operating temperature. Air pump clutch should be disengaged and pump should be stopped.
  2. Disconnect plug from coolant switch and insert jumper wire into connector terminals. Turn ignition off and then on without starting engine. Clutch and switchover valve should operate.
  3. Connect negative lead of voltmeter to terminal 3 of diagnostic plug (on fenderwell). Connect positive lead of voltmeter to battery. With engine running at operating temperature, voltage should be present. Mark voltmeter dial to indicate needle position, then stop engine.
  4. Remove connector from magnetic clutch on air pump. Use jumper wires to connect clutch terminals to ground and battery voltage. Start engine and observe voltmeter. Reading should be as previously marked. Disconnect vacuum lines from switch-over valve and connect them together. Voltmeter reading should increase. If not, proceed to component testing.
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