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PGM-FI TROUBLESHOOTING INFORMATION
GENERAL TROUBLESHOOTING
Intermittent Failure
The term "interm ittent fa ilu re " means a system m ay have had a failure, but it checks OK now. If the IVIL does not com e on,
check for poor contact or loose pins at all connectors related to the circu it th a t o f the troublesho otin g. If the M IL w as on,
but then went out, the o rigin al problem m ay be in term ittent.
Opens and Shorts
"Opens" and "Shorts" are com m on electrical term s. An open is a break in a w ire o r at a connection. A short is an accidental
connection of a w ire to ground or to another w ire. In sim ple electronics, th is usually m eans som ething w ill not w ork at all.
With ECMs this can mean som ething w orks, but not the w ay it's supposed to.
If the MIL has come on
Refer to DTC READOUT (page 6-12).
If the MIL did not stay on
If the MIL did not stay on, but there is a d riv e a b ility problem , do the SYMPTOM TROUBLESHOOTING (page 6-5).
SYSTEM DESCRIPTION
SELF-DIAGNOSIS SYSTEM
The PGM-FI system is equipped w ith the self-diagnostic system . When any a b n o rm a lity occurs in the system , the ECM
turns on the MIL and stores a DTC in its erasable m em ory.
FAIL-SAFE FUNCTION
The PGM-FI system is provided w ith a fail-safe fu n c tio n to secure a m in im u m running capability even w hen there is tro u b le
in the system. When any a bnorm a lity is detected by the self-diagnosis fu n ctio n , running capability is m aintained by pre
programed value in the sim ulated program map. W hen any ab n o rm a lity is detected in th e injector(s), crankshaft position
(CKP) sensor and/or cam shaft position (CMP) sensor, the fail-safe function stops the engine to protect it fro m damage.
DTC (Diagnostic Trouble Code)
• The DTC is composed o f a main code and a sub code and it is displayed as a hyphenated num ber w hen retrieved fro m
the ECM w ith the HDS pocket tester.
The digits in fro n t o f the hyphen are the m ain code, th e y indicate the com ponent o f fu n ctio n failure.
The digits behind the hyphen are the sub code, they detail th e specific sym ptom o f the com ponent o r fu nction failure.
For example, in the case o f the TP sensor:
- DTC 08 - 1 = (TP sensor voltage) - (low er than the specified value)
- DTC 08 - 2 = (TP sensor voltage) - (higher than the specified value).
• The MAP, ECT, TP and IAT sensor diagnosis w ill be m ade according to the voltage o u tp u t o f the affected sensor.
If a failure occurs, the ECM determ ines the Function Failure, com pares th e sensor voltage o u tp u t to the standard value,
and then outputs the corresponding DTC to the HDS Pocket Tester.
For example:
- If the output line (A) on th e MAP sensor is opened, the ECM detects the o u tp u t voltage is about 5 V, then the DTC 1-2
(MAP sensor circu it high voltage) w ill be displayed.
- If the input voltage line (B) on the TP sensor is opened, the ECM detects the o u tp u t voltage is 0 V, then the DTC 8-1 (TP
sensor circuit lo w voltage) w ill be displayed.
5V
FUEL SYSTEM (PGM-FI)
OUTPUT VOLTAGE
5V
6-11
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Table of Contents
Troubleshooting
