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Home >> Isuzu >> 1987 >> Impulse Base, Automatic, AW03-72L >> Repair and Diagnosis >> Engine Performance >> System >> I-TEC Control System >> Diagnosis & Testing >> Diagnostic Procedure >> Entering Diagnostic Mode
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Entering Diagnostic Mode

  1. Turn ignition on. "CHECK ENGINE" light should glow. Locate diagnostic leads. See Fig 1 . Connect diagnostic terminal leads together. If any trouble codes are stored in ECU memory, the "CHECK ENGINE" light will flash 2-digit codes.
  2. The trouble codes will be displayed from lowest to highest numbered code. Each code is repeated three times before the next code sequence is displayed. The trouble codes will be repeated as long as the diagnostic terminals are connected and the ignition is on.
NOTE: An example of trouble codes is as follows: "FLASH", "FLASH", pause, "FLASH", "FLASH", "FLASH" followed by a longer pause identifies trouble code 23. First series of flashes indicates first digit of trouble code. Second series of flashes indicates second digit of trouble code.
Fig 1: I-TEC Diagnostic Leads & Fuse Location
G42742
ECU TROUBLE CODE IDENTIFICATION

Code Problem
12 No Ignition - Normal condition
13 Open Oxygen Sensor Circuit
14 Shorted Coolant Sensor Circuit
15 Incorrect Coolant Sensor Circuit
16 Open Coolant Sensor Circuit
21 Throttle Position Switch Circuits Connected at Same Time
22 Starter Signal Circuit
23 Output Terminal to Ignition Coil Grounded
25 Output Terminal to Vacuum Switching Solenoid Circuit Open or Grounded
33 Open or Shorted Fuel Injector Circuit
35 Ignition Power Transistor Open
41 Bad Signal From Crank Angle Sensor
43 No Idle Position Signal
44 Lean Oxygen Sensor Indication
45 Rich System Indication
51 Faulty ECU
52 Faulty ECU
53 Vacuum Switching Valve
54 Bad Ignition Transistor or Ground
55 Faulty ECU
61 Circuit to Airflow Sensor Bad
62 Circuit to Airflow Sensor Bad
63 No Vehicle Speed Sensor Signal
64 Fuel Injector Transistor or Ground
65 Continuous Signal From Throttle Position Switch
66 Open or Shorted Knock Sensor Circuit
71 Abnormal Signal from TPS
72 Output Terminal to EGR Vacuum Switching Valve Open or Grounded
73 EGR Vacuum Switching Valve or Ground