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Cold Engine

NOTE: Engine coolant temperature must be below 158°F (70°C).
  1. Disconnect air suction lower hose at anti-afterburn valve. Start engine and quickly raise engine speed to 2500 RPM. Close throttle suddenly. If there is no vacuum, proceed to step 5).
  2. If there is vacuum, check for voltage at anti-afterburn control solenoid valve (Blue/Yellow wire). If there is no voltage, check for voltage at control unit connector (Blue wire) with ignition switch on. There should be voltage. If no voltage, check Blue wire between ignition coil and control unit.
  3. Check speed sensor and thermosensor. See SPEED SENSOR  and THERMOSENSOR  . Check for voltage at control unit connector (Black/Yellow wire) with ignition switch on. There should be voltage. If no voltage, check wiring. Check Brown/Black wire for continuity between control unit and ground. There should be continuity.
  4. If there is voltage, disconnect vacuum hose No. 21 from anti-afterburn valve. Check for vacuum at hose. If there is no vacuum, check for leaks or disconnected hose. If there are no defects, replace anti-afterburn control solenoid valve and retest. If there is vacuum, replace anti-afterburn valve and retest.
  5. Raise front of vehicle and support with safety stands. Block rear wheels and set parking brake. Place shift or selector lever in second or "2" position and accelerate. Release throttle suddenly and check for vacuum during deceleration above 3000 RPM (man. trans.) or above 15 MPH (auto. trans.).
  6. If there is vacuum, proceed to HOT ENGINE test. If there is no vacuum, check for voltage at anti-afterburn control solenoid valve above 3000 RPM (man. trans.) or above 15 MPH (auto. trans.).
  7. If there is voltage, check for voltage at control unit connector (Blue wire) with ignition switch on. There should be voltage. If no voltage, check Blue wire between ignition coil and control unit. Check speed sensor and thermosensor. See SPEED SENSOR  and THERMOSENSOR  .
  8. Check for voltage at control unit connector (Black/Yellow wire) with ignition switch on. There should be voltage. If no voltage, check wiring. Check Brown/Black wire for continuity between control unit and ground. There should be continuity.
  9. If there is no voltage, disconnect vacuum hose No. 21 from anti-afterburn valve and check for vacuum above 3000 RPM (man. trans.) or above 15 MPH (auto. trans.). If there is vacuum, replace anti-afterburn control valve and retest.
  10. If there is no vacuum, disconnect vacuum hose No. 20 from anti-afterburn valve. Check for vacuum. If there is no vacuum, check for disconnected hoses or leaks and retest. If there is vacuum, replace anti-afterburn valve and retest.
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