check engine ISUZU TROOPER 1998 Service Repair Manual

6E±229 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0405 ± EGR Low Volt

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Ignition ªON,º engine ªOFFº, review and record
Tech 2 Failure Records Data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using Tech 2, monitor ªDTCº info for DTC P0405
until the DTC P0405 test runs. Note the result.
Does Tech 2 indicates DTC P0405 failed this ignition?
ÐGo to Step 3
Refer to
Diagnostic
Aids
31. Disconnect the EGR valve harness connector.
2. Inspect the EGR valve and connectors for damaged
pin or terminals.
Were there any damaged pins or terminals?
ÐGo to Step 4Go to Step 5
4Repair the damaged pin or terminal.
Is the action complete?
ÐVerify repairÐ
51. Disconnect the EGR harness connector.
2. Ignition ªONº.
3. At the EGR valve, use a DVM to check the voltage
at the 5 volt reference wire (RED) and ground (B).
Did the DVM indicate the specified value?
4±6 VGo to Step 6Go to Step 7
61. Disconnect the EGR harness connector.
2. Measure resistance between terminal B and D.
Was resistance in range?
5±5.5 K
Go to Step 10Go to Step 17
71. Ignition ªONº.
2. At the PCM connector, backprobe with a DVM at the
5 volt reference for the EGR valve.
Did the DVM indicate the specified value?
4±6 VGo to Step 8Go to Step 9
8Repair the open 5 volt reference circuit.
Is the action complete?
ÐVerify repairÐ
9Repair the damaged sensor ground wire.
Is the action complete?
ÐVerify repairÐ
101. Disconnect the EGR harness
2. Use an ohmmeter to measure between the pintle
position pin and the sensor ground pin on the EGR
valve.
NOTE: J-35616 Connector Test Adapter Kit may be
useful for gaining access to the recessed pins on the
valve.
Was the ohmmeter reading approximately equal to the
specified value?
1 to 1.25 K
Go to Step 11Go to Step 17
111. Ignition ªONº.
2. Backprobe with a DVM to measure voltage at EGR
valve pintle position pin and sensor ground pin.
Was voltage in range?
Less than
0.1 V
Go to Step 17Go to Step 12

6E±230
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0405 ± EGR Low Volt

 
StepNo Ye s Value(s) Action
121. Ignition ªONº.
2. Backprobe with a DVM to measure voltage at PCM
sensor ground pin and pintle position pin.
Was voltage in range?
Less than
0.1 V
Go to Step 13Go to Step 18
131. Ignition ªOFFº.
2. Disconnect the EGR harness.
3. Check short circuit between EGR pintle position
circuit and EGR ground circuit.
Was any short circuit?
ÐGo to Step 14Go to Step 18
14Locate and repair the short to ground in the pintle
position circuit
Is the action complete?
ÐVerify repairÐ
151. Ignition ªOFFº.
2. Disconnect the PCM.
3. Ignition ªONº.
4. Measure the voltage between the EGR pintle
position circuit and ground.
Is the measured voltage near the specified value?
Less than
0.1 V
Go to Step 17Go to Step 16
16Check for a short circuit between other wires and the
pintle position circuit
Was any short circuit?
Ð
Repair short
circuit
Verify repair
Go to Step 17
17Replace the EGR valve.
Does DTC P1404 still fail ªspecific DTC test on Tech 2?
ÐGo to Step 18Verify repair
18Examine the PCM pin and terminal connection.
Was there a damaged terminal?
ÐGo to Step 4Go to Step 19
19Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±231 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0406 EGR High Voltage
D06RW106
Circuit Description
The powertrain control module (PCM) monitors the EGR
valve pintle position input to ensure that the valve
responds properly to command from the PCM. If current
pintle position voltage indicates more than 4.8 V and last
more than 10 seconds, then the PCM will set DTC P0406.
Conditions for Setting the DTC

Ignition voltage is between 11 and 16 volts.

EGR pintle position output voltage is more than 4.8 volt
and last more than 10 sec.
Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) as soon as failure detected.
The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in Failure
Records data.
Conditions for Clearing the MIL/DTC

DTC P0404 can be cleared by using Tech 2 ªClear Infoº
function or by disconnecting the PCM battery feed.
Diagnostic Aids
Check for the following conditions:

Poor connection or damaged harness ± Inspect the
wiring harness for damage. If the harness appears to
be OK, observe the EGR actual position display on
Tech 2 while moving connectors and wiring harnesses
related to EGR valve. A change in the display will
indicate the location of the fault.

6E±232
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0406 ± EGR High Voltage

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Ignition ªON,º engine ªOFFº, review and record
Tech 2 Failure Records Data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using Tech 2, monitor ªDTCº info for DTC P0406
until the DTC P0406 test runs. Note the result.
Does Tech 2 indicates DTC P0406 failed this ignition?
ÐGo to Step 3
Refer to
Diagnostic
Aids
31. Disconnect the EGR valve harness connector.
2. Inspect the EGR valve and connectors for damaged
pin or terminals.
Were there any damaged pins or terminals?
ÐGo to Step 4Go to Step 5
4Repair the damaged pin or terminal.
Is the action complete?
ÐVerify repair
Is the action
complete?
51. Disconnect the EGR harness connector.
2. Ignition ªONº.
3. At the EGR valve, use a DVM to check the voltage
at the 5 volt reference wire (RED).
Did the DVM indicate the specified value?
4±6 VGo to Step 8Go to Step 6
61. Ignition ªONº.
2. At the PCM connector, backprobe with a DVM at the
5 volt reference for the EGR valve.
Did the DVM indicate the specified value?
4±6 VGo to Step 7Go to Step 16
7Repair the open 5 volt reference circuit
Is the action complete?
ÐVerify repairÐ
81. Ignition ªOFFº
2. Disconnect the EGR harness.
3. Use a DVM to check for an resistance between D (5
V reference) and B (Sensor Ground) at EGR sensor
terminals.
NOTE: J-35616 Connector Test Adapter Kit may be
useful for gaining access to the recessed pins on the
valve.
Was there measured resistance in range?
5 to 5 K
Go to Step 9Go to Step 15
91. Ignition ªOFFº.
2. Disconnect the EGR harness.
3. Use a DVM to check for an resistance between B
and C at EGR sensor terminal.
Was there open circuit?
ÐGo to Step 15Go to Step 10
101. Ignition ªOFFº.
2. Disconnect the EGR harness at PCM connector.
3. Use a DVM to check for shorted wire between A1
and B7.
Was there shorted wire?
ÐGo to Step 14Go to Step 11

6E±233 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0406 ± EGR High Voltage

 
StepNo Ye s Value(s) Action
111. Ignition ªONº.
2. Use a DVM to backprobe at terminal C of EGR
valve for voltage.
Was measured voltage more than 4.8 V?
more than
4.8 V
Go to Step 12Go to Step 12
121. Ignition ªONº.
2. Stay the EGR harness connected.
3. Check voltage by backproving at PCM B7 terminal.
Was voltage more than 4.8 V?
4.8 VGo to Step 16Go to Step 13
131. Locate short circuit at EGR harness between RED
to RED or GREEN, RED to YEL.
2. Replace EGR harness.
Is the action complete?
ÐVerify repairÐ
14Replace EGR harness.
Is the action complete?
ÐVerify repairÐ
15Replace the EGR valve.
Does DTC P1404 still fail ªspecific DTC test on Tech 2?
ÐGo to Step 16Verify repair
16Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±235 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0502 ± VSS Circuit Low Input

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Does the speedometer work?ÐGo to Step 10Go to Step 3
31. Disconnect the VSS connector.
2. Ignition ªON.º
3. Using a test light to battery +, probe the connector
ground wire.
Did the light illuminate?
ÐGo to Step 5Go to Step 4
4Repair the sensor ground.
Is the action complete?
ÐVerify repairÐ
51. Ignition ªON,º sensor disconnected.
2. Using a DVM, measure at the VSS connector
between ground and voltage supply.
Was the measurement near the specified value?
Battery
voltage
Go to Step 7Go to Step 6
6Repair the open or short to ground which may have
blown the meter fuse.
Is the action complete?
ÐVerify repairÐ
71. Ignition ªON,º VSS disconnected.
2. Using a DVM, measure at the VSS connector
between ground and the wire from the
speedometer.
Was the measurement near the specified value?
7.5-8 VGo to Step 9Go to Step 8
8Check for an open or short circuit between the
speedometer and the VSS.
Was an open or short circuit located?
ÐVerify repairGo to Step 9
9Replace the speedometer.
Is the action complete?
ÐVerify repairÐ

6E±236
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0502 ± VSS Circuit Low Input

 
StepNo Ye s Value(s) Action
101. Ignition ªOFF.º
2. Disconnect the MAF sensor and remove the air
cleaner assembly and filter element to gain access
to the 16-way black connector located immediately
to the rear of the left front headlamp. The connector
attaches the VSS wires from the transmission
harness to the left-side engine harness.
3. Disconnect the black 16-way connector.
4. Select a terminal adapter from kit J 35616 that can
be used with a jumper to supply B+ to the blue wire
with a yellow tracer (transmission side of the
connector).
5. Use another terminal adapter to attach a voltmeter
to the light-green wire with a while tracer (next to the
wire in the previous step.)
6. Disconnect the blue connector next to the black
16-way connector, and locate the black/red tracer
wire at one corner of the blue connector. The
black/red wire is the VSS ground. Use a terminal
adapter to attach a jumper to ground to the
black/red VSS ground wire at the transmission side
of the blue connector.
7. Raise the rear wheels off the ground with
transmission in neutral.
Does the DVM toggle back and forth between 0.6 V and
10 V as the wheels (and driveshaft) are rotated?
ÐGo to Step 11Go to Step 12
11Replace the VSS.
Is the action complete?
ÐVerify repairÐ
12Check for an open or short between the PCM and the
speedometer.
Was a problem found?
ÐVerify repairGo to Step 13
13Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±237 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0562 System Voltage Low
D06RW020
Circuit Description
The powertrain control module (PCM) monitors the
system voltage on the ignition feed terminal to the PCM.
A system voltage DTC will set whenever the voltage is
below a calibrated value.
Conditions for Setting the DTC

Ignition ªON.º

System voltage is below 11.5 volts for 15 minutes.
Action Taken When the DTC Sets

The PCM will not illuminate the malfunction indicator
lamp (MIL).

The PCM will store as Failure Records conditions
which were present when the DTC was set. This
information will not be stored as Freeze Frame data.
Conditions for Clearing the MIL/DTC

A history DTC P0562 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0562 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
If the DTC sets when an accessory is operated, check for
a poor connection or excessive current draw.

6E±238
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0562 ± System Voltage Low

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Using a Tech 2, measure the battery voltage at the
battery.
Is the battery voltage greater than the specified value?
11.5 VGo to Step 3
Charge
battery, then
go to
Step 3
31. Using a Tech 2.
2. Select ªIgnition Voltsº on the Tech 2.
3. Start the engine and raise the engine speed to the
specified value.
4. Load the electrical system by turning on the
headlights, high blower, etc.
Is the ignition voltage approximately equal to the
specified value?
2000 RPM
12.8-14.1 V
Go to Step 4
Go to
Starting/Char
ging
41. Ignition ªOFF.º
2. Disconnect the PCM connector at the PCM.
3. Using a DVM, measure the battery voltage at the
PCM connector A-4.
Is it approximately equal to battery voltage?
Ð
Check for
excessive
current draw
with ignition
ªOFF,º engine
ªOFF.º
Go to Step 5
51. Check for faulty connections at the PCM harness
terminals.
2. Repair as necessary.
Was a repair necessary?
ÐVerify repairGo to Step 6
6Check for an open battery feed circuit to the PCM.
Is the action complete?
ÐVerify repairGo to Step 7
7Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±239 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0563 System Voltage High
Circuit Description
The powertrain control module (PCM) monitors the
system voltage on the ignition feed terminals to the PCM.
A system voltage DTC will set whenever the voltage is
above a calibrated value.
Conditions for Setting the DTC

Ignition ªON.º

System voltage is above 16 volts for 15 minutes.
Action Taken When the DTC Sets

The PCM will not illuminate the malfunction indicator
lamp (MIL).
The PCM will store as Failure Records only conditions
which were present when the DTC was set. This
information will not be stored as Freeze Frame data.
Conditions for Clearing the MIL/DTC

A history DTC P0563 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0563 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
If the DTC sets when an accessory is operated, check for
a poor connection or excessive current draw.
DTC P0563 ± System Voltage High

StepActionValue(s)Ye sNo
1Was the ªON-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Using a Tech 2, measure the battery voltage at the
battery.
Is the battery voltage less than the specified value?
11.5 VGo to Step 3Go to Step 4
31. Charge the battery and clean the battery terminals.
2. Clean the battery ground cable connection if
corrosion is indicated.
Is the battery voltage less than the specified value?
11.5 V
Replace
battery
Go to Step 4
41. Turn ªOFFº all the accessories.
2. Install a Tech 2.
3. Select the ignition voltage parameter on the Tech 2.
4. Start the engine and raise the engine RPM to the
specified value.
Is the voltage more than 2.5 volts greater than the
measurement taken in step 2 or 3?
2000 RPM
Go to
Starting/Char
ging
Go to Step 5
5Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98 model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ