Isuzu Trooper (2000 year). Service manual — part 235
6E–69
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis
(Cont'd)
Step
No
Yes
Value(s)
Action
7
Temporarily substitute the A/C compressor relay in
place of the A/C thermostat relay, then repeat Step 5.
Did the “A/C Request” display indicate “Yes?”
—
Go to
Step 8
Go to
Step 9
8
Replace the original A/C thermostat relay.
Is the action complete?
—
Verify repair
—
9
Dose the blower operate?
—
Go to
Step 10
Go to
Step 11
10
Repair the blower.
Is the action complete?
—
Verify repair
—
11
Check for a faulty 10A A/C fuse in the underdash fuse
panel.
Was the 10A fuse OK?
—
Go to
Step 13
Go to
Step 12
12
Check for short circuit and make repairs if necessary.
Replace the 10A A/C fuse.
Is the action complete?
—
Verify repair
—
13
1. Remove the glove box to gain access to the A/C
thermostat.
2. Disconnect the thermostat connector.
3. Attach a fused jumper between ground and the
PNK/GRN wire at the thermostat.
4. A/C “ON.”
5. Blower “ON.”
Dose A/C request indicate “YES” on the Tech 2?
—
Go to
Step 14
Go to
Step 17
14
1. Ignition “ON.”
2. Use a DVM to check voltage at the electronic A/C
thermostat.
Was voltage equal to the specified value?
B+
Go to
Step 17
Go to
Step 15
15
Check for an open (LT GRN) between the thermostat
and the A/C switch.
Was the wire open?
—
Go to
Step 16
Go to
Step 17
16
Repair the open wire (LT GRN) between the thermostat
and the A/C switch.
Is the action complete?
—
Verify repair
—
17
Check for an open circuit between A/C thermostat relay
and PCM A/C request terminal (F45).
Was there an open circuit?
—
Go to
Step 18
Go to
Step 19
18
Repair the open circuit between the PCM and A/C
thermostat relay.
Is the action complete?
—
Verify repair
—
19
1. Ignition “ON.”
2. Use a DVM to check voltage at the A/C pressure
switch (BRN).
Was voltage equal to the specified value?
B+
Go to
Step 21
Go to
Step 20
20
Repair the open circuit between the 10A A/C fuse and
the pressure switch.
Is the action complete?
—
Verify repair
—
6E–70
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis
(Cont'd)
Step
No
Yes
Value(s)
Action
21
Use an ohmmeter to check continuity between the
pressure switch (GRN/WHT) and the A/C thermostat
relay (GRN/WHT).
Was the circuit open?
—
Go to
Step 22
Go to
Step 23
22
Repair the open circuit between the pressure switch
and the A/C thermostat relay.
Is the action complete?
—
Verify repair
—
23
Check for damaged pin or terminal at F45 of the PCM.
Was a damaged pin or terminal found?
—
Go to
Step 24
Go to
Step 25
24
Repair the damaged pin or terminal.
Is the action complete?
—
Verify repair
—
25
Replace the PCM.
IMPORTANT: The replacement PCM must be
programmed. Refer to
On-Vehicle Servicein
Powertrain Control Module 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?
—
Verify repair
—
26
1. Remove the A/C compressor relay.
2. Ignition “ON.”
3. Use a DVM to check voltage at both of the BRN
wires at the A/C compressor relay socket.
Is the voltage equal to the specified value?
B+
Go to
Step 28
Go to
Step 27
27
Repair the faulty BRN wire between the A/C fuse and
the A/C compressor relay .
Is the action complete?
—
Verify repair
—
28
1. A/C compressor relay removed.
2. Engine idling.
3. A/C “ON.”
4. Blower “ON.”
5. Use a DVM to measure voltage between the
GRN/BLK wire at the A/C compressor relay socket
and battery
±
.
Did the DVM indicate the specified value?
B+
Go to
Step 32
Go to
Step 29
29
Check for an open GRN/BLK wire between PCM
terminal F4 and the A/C compressor relay.
Was the wire open?
—
Go to
Step 30
Go to
Step 31
30
Repair the open GRN/BLK wire between the PCM and
the A/C compressor relay.
Is the action complete?
—
Verify repair
—
31
Check for a damaged pin or terminal at F4 of the PCM.
Was a damaged pin or a terminal found?
—
Go to
Step 24
Go to
Step 25
6E–71
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis
(Cont'd)
Step
No
Yes
Value(s)
Action
32
1. A/C compressor relay removed.
2. Connect a fused jumper at the A/C compressor
relay socket between either BRN wire and the
BRN/YEL wire.
3. Engine idling.
4. A/C “ON.”
5. Blower “ON.”
Did the compressor magnetic clutch engage?
—
Go to
Step 33
Go to
Step 34
33
Repair the A/C compressor relay.
Is the action complete?
—
Verify repair
—
34
Check for an open circuit between the A/C compressor
relay and the A/C clutch.
Was an open circuit found?
—
Go to
Step 35
Go to
Step 36
35
Repair the open circuit between the compressor Clutch
and the A/C compressor relay.
Is the action complete?
—
Verify repair
—
36
Service the compressor clutch or replace the
compressor due to a faulty internal overheat switch.
Is the action complete?
—
Verify repair
—
37
1. Remove the A/C compressor relay.
2. Idle the engine.
Is the compressor clutch still engaged when A/C is not
selected?
—
Go to
Step 38
Go to
Step 39
38
Repair the short to voltage between the A/C clutch and
A/C compressor relay.
Is the action complete?
—
Verify repair
—
39
1. Reinstall the A/C compressor relay.
2. Remove the A/C thermostat relay.
3. Engine idling.
Is the compressor clutch still engaged when A/C is not
selected?
—
Go to
Step 40
Go to
Step 42
40
Use a DVM to check for a short to ground between the
A/C compressor relay and F4 of the PCM.
Was a short detected?
—
Go to
Step 41
Go to
Step 25
41
Repair the short to ground between the PCM and A/C
compressor relay.
Is the action complete?
—
Verify repair
—
42
Repair the short to ground between the A/C thermostat
relay and the electronic thermostat.
Is the action complete?
—
Verify repair
—
6E–72
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Electronic Ignition System Diagnosis
If the engine cranks but will not run or immediately stalls,
the Engine Cranks But Will Not Start chart must be used
to determine if the failure is the ignition system or the fuel
system. If DTC P0300 through P306, P0341, or P0336 is
set, the appropriate diagnostic trouble code chart must be
used for diagnosis.
If a misfire is being experienced with no DTC set, refer to
the
Symptoms section for diagnosis.
EVAP Canister Purge Solenoid and
EVAP Vacuum Switch
A continuous purge condition with no purge commanded
by the PCM will set a DTC P1441. Refer to the DTC charts
for further information.
Visual Check of The Evaporative
Emission Canister
D
If the canister is cracked or damaged, replace the
canister.
D
If fuel is leaking from the canister, replace the canister
and check hoses and hose routing.
Fuel Metering System Check
Some failures of the fuel metering system will result in an
“Engine Cranks But Will Not Run” symptom. If this
condition exists, refer to the
Cranks But Will Not Run
chart. This chart will determine if the problem is caused
by the ignition system, the PCM, or the fuel pump
electrical circuit.
Refer to
Fuel System Electrical Test for the fuel system
wiring schematic.
If there is a fuel delivery problem, refer to
Fuel System
Diagnosis, which diagnoses the fuel injectors, the fuel
pressure regulator, and the fuel pump. If a malfunction
occurs in the fuel metering system, it usually results in
either a rich HO2S signal or a lean HO2S signal. This
condition is indicated by the HO2S voltage, which causes
the PCM to change the fuel calculation (fuel injector pulse
width) based on the HO2S reading. Changes made to the
fuel calculation will be indicated by a change in the long
term fuel trim values which can be monitored with a
Tech 2. Ideal long term fuel trim values are around 0%;
for a lean HO2S signal, the PCM will add fuel, resulting in
a fuel trim value above 0%. Some variations in fuel trim
values are normal because all engines are not exactly the
same. If the evaporative emission canister purge is “ON,”
the fuel trim may be as low as –38%. If the fuel trim values
are greater than +23%, refer to
DTC P0131, DTC P0151,
DTC P0171, and DTC 1171 for items which can cause a
lean HO2S signal.
Fuel System Pressure Test
A fuel system pressure test is part of several of the
diagnostic charts and symptom checks. To perform this
test, refer to
Fuel Systems Diagnosis.
Fuel Injector Coil Test Procedure and
Fuel Injector Balance Test Procedure
T32003
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. Relieve the fuel pressure by connecting the J
34730-1 Fuel Pressure Gauge to the fuel pressure
connection on the fuel rail.
CAUTION: In order to reduce the risk of fire and
personal injury, wrap a shop towel around the fuel
pressure connection. The towel will absorb any fuel
leakage that occurs during the connection of the fuel
pressure gauge. Place the towel in an approved
container when the connection of the fuel pressure
gauge is complete.
Place the fuel pressure gauge bleed hose in an
approved gasoline container.
With the ignition switch “OFF,” open the valve on the
fuel pressure gauge.
3. Record the lowest voltage displayed by the DVM
after the first second of the test. (During the first
second, voltage displayed by the DVM may be
inaccurate due to the initial current surge.)
Injector Specifications:
Resistance Ohms
Voltage Specification at
10
°
C-35
°
C (50
°
F-95
°
F)
11.8 – 12.6
5.7 – 6.6
D
The voltage displayed by the DVM should be within
the specified range.
D
The voltage displayed by the DVM may increase
throughout the test as the fuel injector windings
warm and the resistance of the fuel injector windings
changes.
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