Service Manual — page 138 of 715

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3-48 FUEL SYSTEM (DFI)
Self-Diagnosis

Service    Parts or        Output Signal Usable
                                                                      Backups by ECU
Codes      Function         Range or Criteria
                                                       If the injector #4 fails (no signal, wiring short
                         The injector must send
          Fuel Injector                                or open), the ECU shuts off the signal to the
  44                     signals continuously to the
               #4*                                     injector. Fuel is not supplied to the cylinder #4,
                         ECU.
                                                       though the engine keeps running.
                                                       If the stick coil #1 primary winding has failures
                         The ECU sends                 (no signal, wiring short or open), the ECU shuts
                         signals (output voltage)      off the injector #1 to stop fuel to the cylinder
  51      Stick Coil #1*
                         continuously to the stick     #1, though the engine keeps running. Then
                         coil.                         the ECU stops the KTRC and the feedback
                                                       control with the oxygen sensor.
                                                       If the stick coil #2 primary winding has failures
                         The ECU sends                 (no signal, wiring short or open), the ECU shuts
                         signals (output voltage)      off the injector #2 to stop fuel to the cylinder
  52      Stick Coil #2*
                         continuously to the stick     #2, though the engine keeps running. Then
                         coil.                         the ECU stops the KTRC and the feedback
                                                       control with the oxygen sensor.
                                                       If the stick coil #3 primary winding has failures
                         The ECU sends                 (no signal, wiring short or open), the ECU shuts
                         signals (output voltage)      off the injector #3 to stop fuel to the cylinder
  53      Stick Coil #3*
                         continuously to the stick     #3, though the engine keeps running. Then
                         coil.                         the ECU stops the KTRC and the feedback
                                                       control with the oxygen sensor.
                                                       If the stick coil #4 primary winding has failures
                         The ECU sends                 (no signal, wiring short or open), the ECU shuts
                         signals (output voltage)      off the injector #4 to stop fuel to the cylinder
  54      Stick Coil #4*
                         continuously to the stick     #4, though the engine keeps running. Then
                         coil.                         the ECU stops the KTRC and the feedback
                                                       control with the oxygen sensor.
          Radiator Fan When the radiator fan relay
  56                                                                             –
              Relay      is OFF, the relay is opened.
                         The actuator operates         If the subthrottle valve actuator fails (the
           Subthrottle
                         open and close of the         signal is out to the usable range, wiring short
  62          Valve
                         subthrottle valve by the      or open), the ECU stops the current to the
            Actuator
                         pulse signal from the ECU. actuator.
                         The air switching valve
                         controls the flow of the
          Air Switching
  64                     secondary air by opening                                –
              Valve
                         and shutting the solenoid
                         valve.
                         The oxygen sensor heater If the oxygen sensor heater fails (wiring short
             Oxygen
                         raises temperature of         or open), the ECU stops the current to the
  67         Sensor
                         the sensor for its earlier    heater, and it stops the feedback mode of the
              Heater
                         activation.                   oxygen sensor.
          Purge Valve
                         The purge valve controls
          (Other than
                         the flow of the purge air for
  3A       US, CA, ID                                                            –
                         the canister and shutting
          and SEA-B2
                         the solenoid valve.
             Models)