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Isuzu Code Retrieval
Accessing Diagnostic Trouble Codes
Carbureted Models
Except I-MARK
Connect white (test lead) and black (ground lead) wires that are
branched from harness approximately eight inches from ECM. After leads are
grounded, the "Check Engine" lamp will flash the appropriate
diagnostic trouble code's. The DTC's are indicated by a pulsing of the
lamp. Two pulses followed by a short time lapse, then three pulses would
indicate DTC 23 and so on. If only one diagnostic trouble code is stored,
the DTC will repeat continuously until test leads are disconnected. If
more than one diagnostic trouble code is stored, each DTC will repeat
three times, starting with the lowest, then proceed to the next DTC. After
all DTC's have been displayed, the pattern will repeat.
I-MARK 1984-85
Connect male and female test leads taped into wire harness near ECM.
After leads are connected, the "Check Engine" lamp will flash
the appropriate diagnostic trouble codes. The DTC's are indicated by a
pulsing of the lamp. Two pulses followed by a short time lapse, then three
pulses would indicate DTC 23 and so on. If only one diagnostic trouble
code is stored, the DTC will repeat continuously until test leads are
disconnected. If more than one diagnostic trouble code is stored, each DTC
will repeat three times, starting with the lowest, then proceed to the
next DTC. After all DTC's have been displayed, the pattern will repeat.
1988-89
A three-terminal connector (ALDL), located near the ECM connector, is
used to actuate the Engine Control Module (ECM) trouble code memory within
the module. Two terminals (A and C) of this connector are used to activate
the diagnostic trouble code system in the ECM. With the ignition switch
turned On, engine Oft, connect a jumper wire between terminals A and C.
The "Check Engine" tamp will begin by flashing a DTC 12. DTC 12
consists of one flash, a short pause, then two flashes. There will be a
longer pause and a code 12 will repeat two more times. This code indicates
the self-diagnostic system is operating. The cycle will then repeat until
the engine is started or the ignition is switched Oft. In most cases,
DTC's will be checked with the engine running since no DTC's other than
DTC 12 or 51 will be present without the engine running. Remove jumper
wire from ALDL connector before starting engine. Reconnect jumper wire
after engine is running.
Throttle Body Fuel Injection
The ECM test connection is located under the center console.
A built-in, self diagnostic system will identify problems most likely to
occur in the throttle body fuel injection system. When a problem is
detected, the diagnostic system will illuminate the "Check Engine"
lamp in the instrument panel.
When the engine is started, the Check Engine lamp should turn oft. If the
lamp remains lit, the self diagnostic has detected a problem. To determine
where the problem exists, ground the "Test" terminal of the
connector with the ignition On, engine Oft and observe diagnostic trouble
code display. Each DTC will flash three times in numerical order (lowest to
highest). Each diagnostic trouble code will indicate a fault in a particular
circuit.
Multi-Port Fuel Injection
Amigo, Pickup, Rodeo & Trooper II
On Amigo, Pickup and Rodeo (except 1993-95 models W/3.2L engine),
connect the single wire diagnostic leads located behind the left hand kick
panel together. On Trooper models to 1991, the single wire diagnostic
connectors are located under the center console. On 1992-95 Trooper &
1993-95 Rodeo models W/3.2L engine, connect a jumper wire between data
link connector terminals 1 and 3. On 1992-95 Trooper models the data link
connector is located behind the lower front of the instrument panel. On
1993-95 Rodeo models W/3.2 engine, the data link is located under the left
hand side of the instrument panel. On all models, turn the ignition switch
to the On position. At this point, the "Check Engine" lamp
should flash.
Impulse & Stylus
The provision for reading diagnostic trouble codes is through a white
three cavity ALDL connector located behind the passenger side kick panel.
The ECM has a battery voltage line to the ALDL connector. Using a jumper
wire, connect this terminal to ground. The ECM will then toggle the
"Check Engine" lamp to emit any trouble codes stored in the
memory of the ECM.
If no DTC's are stored, the tamp will flash DTC 12. If a diagnostic
trouble code's) exist the lowest number DTC will flash first. Each DTC
will flash three times.
Oasis
If the malfunction indicator/check engine lamp remains illuminated or
comes on while the engine is operating, the ECM has detected a malfunction
and has stored a diagnostic trouble code in its memory. To access the
diagnostic trouble code memory, connect an OBD II scan tool to the 16-pin
DLC connector located behind the right-hand side of the front console.
Turn the ignition switch On and begin troubleshooting as indicated by the
tester. Follow the tester's prompts to diagnose the error. If unsure how
to operate the OBD II scan tool, refer to the tools user's manuals for
specific operating instructions.
Clearing Diagnostic Trouble Codes
Carbureted Models
Diagnostic trouble codes can be cleared by removing voltage to the ECM
for 10 seconds. After a fault has been corrected, remove the ECM fuse or
disconnect battery cables for 10 seconds.
Fuel Injected Models
Except Oasis
To prevent damage to the ECM when disconnecting the battery ground
cable, ensure the ignition key is in the Off position. Disconnecting the
battery ground cable for 30 seconds or longer will clear all stored
diagnostic trouble codes from the ECM memory.
Oasis
After making necessary repairs, the diagnostic trouble codes should be
cleared from the ECM (ECU) memory. This can be done by either turning off
the ignition switch and removing the back-up radio (7.5A) fuse from the
under hood fuse/relay box for 10 seconds, or by using the OBD II scan tool
to clear the ECM's memory.
It will also be necessary to remove the SCS Service Connector if it had
been connected, and reset the PCM. Turn the ignition to OFF, then
disconnect the scan tool.
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