Isuzu Trooper (1998-2002 year). Service manual — part 423
6E–62
6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS
On-Board Diagnostic (OBD) System Check
D06RY00053
Circuit Description
The on-board diagnostic system check is the starting
point for any driveability complaint diagnosis. Before
using this procedure, perform a careful visual/physical
check of the PCM and engine grounds for cleanliness and
tightness.
The on-board diagnostic system check is an organized
approach to identifying a problem created by an
electronic engine control system malfunction.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed–through wire insulation or a wire broken inside the
insulation. Check for poor connections or a damaged
harness. Inspect the PCM harness and connector for
improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. The MIL (“Check Engine lamp”) should be “ON”
steady with the ignition “ON ” and the engine “OFF”.
If not, the “No MIL” chart should be used to isolate
the malfunction.
3. The SVS (“Service Vehicle Soon”) lamp should be
“ON” steady with the ignition “ON ”and the engine
“OFF”. If not, the “No SVS lamp”chart should be
used to isolate the malfunction.
4. Checks the Class 2 data circuit and ensures that the
PCM is able to transmit serial data.
5. This test ensures that the PCM is capable of
controlling the MIL (“Check Engine lamp”) and the
MIL (“Check Engine lamp”) driver circuit is not
shorted to ground.
6. This test ensures that the PCM is capable of
controlling the SVS (“Service Vehicle Soon”) lamp
and the SVS (“Service Vehicle Soon”) lamp driver
circuit is not shorted to ground.
8. Check the DTCs (System ,Volts Supply circuit).
9. Check the DTCs (PCM{Software} detect Errors).
12.If the engine will not start, the Cranks But Will Not
Run chart should be used to diagnose the condition.
15.A Tech 2 parameter which is not within the typical
range may help to isolate the area which is causing
the problem.
16.This vehicle is equipped with a PCM which utilizes
an electrically erasable programmable read only
memory (EEPROM). When the PCM is replaced,
the new PCM must be programmed. Refer to
PCM
Replacement and Programming Procedures in
Powertrain Control Module (PCM) and Sensors of
this section.
11.If the starter motor will not start, the starter control
system chart should be used to diagnose the
condition.
6E–63
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
On-Board Diagnostic (OBD) System Check
Step
Action
Value(s)
Yes
No
1
1. Ignition “ON”, engine “OFF”.
2. Observe the Service Vehicle Soon (SVS) lamp.
Is the SVS lamp flashing?
—
Refer to
Immobilizer
System
Workshop
Manual
Go to
Step 2
2
1. Ignition “ON”, engine “OFF”.
2. Observe the malfunction indicator lamp (MIL or
“Check Engine lamp”).
Is the MIL (“Check Engine lamp”)“ON”?
—
Go to
Step 3
Go to
No
MIL(“Check
Engine lamp”)
3
1. Ignition “ON”, engine “OFF”.
2. Observe the SVS (“Service Vehicle Soon”) lamp.
Is the SVS (“Service Vehicle Soon”) lamp “ON”?
—
Go to
Step 4
Go to
No
SVS
(“Service
Vehicle
Soon”) lamp
4
1. Ignition “OFF”.
2. Install Tech 2.
3. Ignition “ON”.
4. Attempt to display PCM engine data with the
Tech 2.
Does the Tech 2 display PCM data?
—
Go to
Step 5
Go to
Step 13
5
1. Using the Tech 2 output tests function, select MIL
(“Check Engine lamp”) control and command the
MIL (“Check Engine Lamp”) “OFF”.
2. Observe the MIL (“Check Engine lamp”).
Did the MIL (“Check Engine lamp”) turn “OFF”?
—
Go to
Step 6
Go to
MIL(“Check
Engine lamp”)
On Steady
6
1. Using the Tech 2 output tests function, select RPL
(“Reduced Power lamp”) control and command the
RPL (“Reduced Power lamp”) “OFF”.
2. Observe the SVS (“Service Vehicle Soon”) lamp.
Did the SVS (“Service Vehicle Soon”) lamp turn “OFF”?
—
Go to
Step 7
Go to
SVS
(“Service
Vehicle
Soon”) lamp
On Steady
7
Select “Display DTCs” with the Tech 2.
Are any DTCs stored?
—
Go to
Step 8
Go to
Step 12
8
Stored DTCs.
P0562, P0563, P0601, P0602, P0604, P0606, P1625,
P1635, P1639, P1640, P1650
Are the applicable DTCs stored?
—
Go to
applicable
DTC table
Go to
Step 9
9
Stored DTCs.
P1514, P1515, P1516, P1523, P1125, P1290, P1295,
P1299
Are the applicable DTCs stored?
—
Go to
applicable
DTC table
Go to
Step 10
10
Stored DTCs.
1. P0425, P0106, P0107, P1107, P0401, P1404,
P0405, P1120, P1221, P1515, P1516, P1275,
P1635, P1271, P1273, P1285, P1272
2. P0336, P0337, P1220, P1515, P1221, P1516,
P1280, P1639, P1271, P1272
Are the applicable DTCs stored?
—
Go to
“Multiple
PCM
Information
sensor DTCs
Set”
Go to
Step 11
6E–64
6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS
On-Board Diagnostic (OBD) System Check
(Cont'd)
Step
No
Yes
Value(s)
Action
11
Attempt to crank the starter motor
Did the starter motor crank?
—
Go to
Step 11
Go to
Starter
control
system
12
Attempt to start the engine.
Did the engine start and continue to run?
—
Go to
Step 7
Go to
Cranks
But Will Not
Run
13
Compare PCM data values displayed on the Tech 2 to
the typical engine scan data values.
Are the displayed values normal or close to the typical
values?
—
Go to
Symptom
Refer to
indicated
Component
System
Checks
14
1. Ignition “OFF”, disconnect the PCM.
2. Ignition “ON”, engine “OFF”.
3. Check the Class 2 data circuit for an open, short to
ground, or short to voltage. Also, check the DLC
ignition feed circuit for an open or short to ground
and the DLC ground circuit for an open.
4. If a problem is found, repair as necessary.
Was a problem found?
—
Go to
Step 3
Go to
Step 15
15
1. Attempt to reprogram the PCM. Refer to
Powertrain
Control Module (PCM) in On-Vehicle Service.
2. Attempt to display PCM data with the Tech 2.
Does the Tech 2 display PCM engine data?
—
Go to
Step 3
Go to
Step 16
16
Replace the PCM.
IMPORTANT: The replacement PCM must be
programmed. Refer to
ON-Vehicle Service in Power
Control Module and Sensors for procedures.
And also refer to latest Service Bulletin. Check to see
if the latest software is released or not. And then Down
Load the LATEST PROGRAMMED SOFTWARE to the
replacement PCM.
Is the action complete?
—
Go to
Step 3
—
6E–65
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis
D06RY00159
Circuit Description
When air conditioning and blower fan are selected, and if
the system has a sufficient refrigerant charge, a 12-volt
signal is supplied to the A/C request input of the
powertrain control module (PCM). The A/C request
signal may be temporarily canceled during system
operation by the electronic thermostat in the evaporator
case. When the A/C request signal is received by the
PCM, the PCM supplies a ground from the compressor
clutch relay if the engine operating conditions are within
acceptable ranges. With the A/C compressor relay
energized, voltage is supplied to the compressor clutch
coil.
The PCM will enable the compressor clutch to engage
whenever A/C has been selected with the engine running,
unless any of the following conditions are present:
D
The throttle is greater than 90%.
D
The ignition voltage is below 10.5 volts.
D
The engine speed is greater than 4500 RPM for 5
seconds or 5400 RPM.
D
The engine coolant temperature (ECT) is greater
than 125
°
C (257
°
F).
D
The intake air temperature (IAT) is less than 5
°
C
(41
°
F).
D
The power steering pressure switch signals a high
pressure condition.
Diagnostic Aids
To diagnose an the intermittent fault, check for following
conditions:
D
Poor connection at the PCM–Inspect connections for
backed-out terminals, improper mating, broken locks,
improperly formed or damaged terminals, and poor
terminal-to-wire connection.
D
Damaged harness–Inspect the wiring harness for
damage. If the harness appears to OK, observe the
A/C clutch while moving connectors and wiring
harnesses related to the A/C. A sudden clutch
malfunction will indicate the source of the intermittent
fault.
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