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G - T E STS W /C O DES
1991 Mitsubishi Montero
1990-91 ENGINE PERFORMANCE
Chrysler Motors/Mitsubishi Self-Diagnostics
Dodge; Colt, Colt Vista, Colt Wagon
Eagle; Summit
Mitsubishi; Eclipse, Galant, Mirage, Montero, Precis (1990)
Plymouth; Colt, Colt Vista, Colt Wagon
INTRODUCTION
If no faults were found while performing F - BASIC TESTING,
proceed with self-diagnostics. If no fault codes or only pass codes
are present after entering self-diagnostics, proceed to H - TESTS W/O
CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START,
etc.).
SELF-DIAGNOSTIC SYSTEM
Use Chrysler Motors code charts when using Chrysler's
Diagnostic Readout Box (DRB-II). If DRB-II is not available or if
working on a Mitsubishi Motors vehicle, system diagnosis can only be
accomplished using a voltmeter or appropriate scan tester. To diagnose
Chrysler Motors and Mitsubishi models using a voltmeter, see
ENTERING ON-BOARD DIAGNOSTICS (USING VOLTMETER) in this article.
SYSTEM DIAGNOSIS
SYSTEM DIAGNOSIS DESCRIPTION
NOTE: Chrysler Motors recommends using DRB-II to diagnose system.
Voltmeter usage has limited diagnostic capabilities but can
be used if DRB-II is not available or if working on a
Mitsubishi Motors vehicle.
The Engine Control Unit (ECU) monitors several different
engine control system circuits. If an abnormal input signal occurs, a
fault code is stored in ECU memory and given a fault code number. Each
circuit has its own fault number and message. A specific fault code
indicates a particular system failure, but it DOES NOT indicate that
cause of failure is necessarily within system. A fault code DOES NOT
condemn any specific component; it simply points out a probable
malfunctioning area. If a critical fault code is set, the ECU will
turn on CHECK ENGINE light. All fault codes except speed sensor are
considered critical.
Fault codes can be confirmed by using a voltmeter on Chrysler
Motors and Mitsubishi models or Chrysler's Diagnostic Readout Box
(DRB-II) on Chrysler Motors vehicles. See
ENTERING ON-BOARD DIAGNOSTICS (USING VOLTMETER) or ENTERING ON-BOARD
DIAGNOSTICS (USING DRB-II) in this article. By using the DRB-II, the
self-diagnostic capabilities of this system can simplify testing and
reduce diagnostic time.
System malfunctions encountered are identified as either hard
failures or intermittent failures as determined by the ECU.
HARD FAILURES
Hard failures cause CHECK ENGINE light to illuminate and
remain on until the malfunction is repaired. If light comes on and
