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DTC P0271: Injector Circuit High Input - Cylinder 4
 
 
 
 
CIRCUIT OPERATION
  • The injector power is supplied from the MFI relay.
  • The ECM controls the injector by turning the power transistor in the ECM "ON" and "OFF".
 
 
TECHNICAL DESCRIPTION
  • The amount of fuel injected by the injector is controlled by the amount of continuity time the coil is grounded by the ECM.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • The ECM detects short malfunction.
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
DTC SET CONDITIONS
Logic Flow Chart
Check Condition
  • Engine is running.
  • Battery positive voltage is between 10 and 16.5 volts.
Judgment Criterion
  • The coil current is more than 4.5 amperes with the injector driving for 2 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 22 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be stored are: )
  • No. 4 cylinder injector failed.
  • Shorted No. 4 cylinder injector circuit, harness damage or connector damage.
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Using scan tool (M.U.T.-III), check actuator test item 1: Injectors.
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Start the engine and run at idle.
(3) Warm up the engine to normal operating temperature: 80°C to 95°C (176°F to 203°F).
(4) Set scan tool (M.U.T.-III) to the actuator testing mode for item 1 Injectors.
  • The idle should become slightly rougher.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Is the actuator operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Go to Step 2.
 
STEP 2. Check No. 4 cylinder injector itself.
Refer to Injector Check .
Is the measured resistance normal?
Go to Step 3.
Replace the No. 4 cylinder injector. Then go to Step 5.
 
STEP 3. Check of short to power supply in INJ4 line between No. 4 cylinder injector connector and ECM connector.
Is the harness wire in good condition?
Go to Step 4.
Repair the connector(s) or wiring harness. Then go to Step 5.
 
STEP 4. Using the oscilloscope, check the No. 4 cylinder injector.
  • Engine: Idling
  • Transmission: P range
  • Voltage between terminal INJ4 and ground.
OK: Waveforms should be displayed on inspection procedure using an oscilloscope (Refer to ).
Is the wave pattern normal?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Replace the ECM (Refer to, Removal and Installation ). Then go to Step 5.
 
STEP 5. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 22 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0271 stored?
Retry the troubleshooting.
The inspection is complete.