sensor ISUZU TROOPER 1998 Service Repair Manual

6E±202
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0342 CMP Sensor Circuit Low
D06RW032
Circuit Description
The CMP signal produced by the camshaft position
(CMP) sensor pulses when the engine is running and
crankshaft position (CKP) sync pulses are also being
received. The hall type CMP sensor and the CKP sensor
share 5 V and ground connections at the powertrain
control module (PCM). The third wire at the sensor is a
signal circuit to the PCM. The PCM uses the CMP signal
pulses to initiate sequential fuel injection. The PCM
constantly monitors the number of pulses on the CMP
signal circuit and compares the number of CMP pulses to
the number of 58X reference pulses received. If the PCM
does not receive pulses on the CMP reference circuit,
DTC P0342 will set and the PCM will initiate injector
sequence without the CMP signal with a one in six chance
that injector sequence is correct. The engine will continue
to start and run normally, although the misfire diagnostic
will be affected if a misfiring condition occurs.
Conditions for Setting the DTC

The engine is running.

The CMP sensor signal is not received by the PCM
once every 6 cylinders.

The above condition occurs for 10 seconds.
Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.

The PCM will initiate injector sequence without the
CMP signal with a one in six chance that the injector
sequence is correct.

The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.

6E±203 ENGINE DRIVEABILITY AND EMISSIONS
Conditions for Clearing the MIL/DTC

DTC P0342 can be cleared by using Tech 2 ªClear Infoº
function or by disconnecting the PCM battery feed.
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 connection ± Inspect the PCM harness and
connectors for improper mating, broken locks,
improperly formed or damaged terminals, and poor
terminal to wire connection.

Damaged harness ± Inspect the wiring harness for
damage. If the harness appears to be OK, disconnect
the PCM, turn the ignition on and observe a voltmeterconnected to the CMP signal circuit at the PCM
harness connector while moving connectors and
wiring harnesses related to the ICM and the CMP
sensor. A change in voltage will indicate the location
of the fault.Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Ensures that the fault is present.
14.Determines whether the fault is being caused by a
missing camshaft magnet or a faulty PCM. The
voltage measured in this step should read around 4
volts, toggling to near 0 volts when the CMP sensor
interfaces with the camshaft magnet.
DTC P0342 ± CMP Sensor Circuit Low

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
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using Tech 2, monitor ªSpecific DTCº information
for DTC P0342 until the DTC P0342 test runs.
5. Note test result.
Does Tech 2 indicate DTC P0342 failed this ignition?
ÐGo to Step 3
Refer to
Diagnostic
Aids
31. Ignition ªON.º
2. Disconnect the CMP sensor.
3. Measure the voltage between the sensor feed
circuit and the sensor ground circuit at the CMP
sensor harness connector.
Does the voltage measure near the specified value?
4-6 VGo to Step 7Go to Step 4
41. Ignition ªOFF,º disconnect the PCM and the CMP
sensor.
2. Check for poor connections at the camshaft
position sensor.
3. If a problem is found, repair it as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Check for poor connections at the PCM.
2. If a problem is found, repair it as necessary.
Was a problem found?
ÐVerify repair Go to Step 6
61. Check the following circuits between the PCM and
the CMP sensor:

The sensor feed circuit. Open or short to
ground?

The sensor ground circuit. Open or short to
voltage?
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairÐ

6E±204
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0342 ± CMP Sensor Circuit Low

 
StepNo Ye s Value(s) Action
71. Ignition ªON,º engine ªOFF.º
2. Measure the voltage between the CMP sensor
signal circuit and the sensor ground circuit at the
CMP sensor harness connector.
Does the voltage measure near the specified value?
4-6 VGo to Step 8Go to Step 9
81. Turn the ignition ªOFF.º
2. Disconnect the PCM and connect a DVM to monitor
voltage on the camshaft position signal circuit at the
PCM connector.
3. Ignition ªON.º
4. Monitor the voltage display on the DVM while
repeatedly touching the CMP sensor signal circuit
at the CMP sensor connector with a test light to
ground.
Does the DVM voltage display switch between 0 and
approximately 5 volts when the test light is touched to
the CMP sensor signal circuit?
ÐGo to Step 12Go to Step 9
91. Ignition ªOFF.º
2. Leave the PCM disconnected.
3. Ignition ªON.º
4. Probe the camshaft position signal circuit at the
PCM connector with a test light to B+.
5. If the test light is ªON,º locate and repair the short to
ground in the camshaft position input signal circuit.
Was either circuit shorted to ground?
ÐVerify repairGo to Step 10
101. Ignition ªOFF.º
2. Leave the PCM disconnected.
3. Ignition ªON.º
4. Probe the camshaft position signal circuit with a test
light to ground.
5. If the test light is ªON,º locate and repair the short to
voltage in the camshaft position input signal circuit.
Was the test light ªONº?
ÐVerify repairGo to Step 11
111. Ignition ªOFF,º disconnect the PCM (leave the CMP
sensor disconnected).
2. Ignition ªON,º check the following circuit:

The CMP sensor signal circuit for an open.
3. If a problem is found, repair it as necessary.
Was a problem found?
ÐVerify repairÐ
121. Ignition ªON.º
2. Remove the CMP sensor from the engine front
cover (leave the sensor wiring connected).
3. Place a magnet on the CMP sensor. If you use a
magnet that is too small to cover the face of the
sensor, test on every part of the sensor face
because only a small area will respond to this test.
Does the DVM display a voltage near the specified
value?
0 VGo to Step 14Go to Step 13
13Replace the camshaft position sensor.
Is the action complete?
ÐVerify repairÐ

6E±205 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0342 ± CMP Sensor Circuit Low

 
StepNo Ye s Value(s) Action
141. Reinstall the CMP sensor to the engine front cover.
2. Observe the DVM connected to monitor voltage on
the camshaft position signal circuit while cranking
the engine.
Does the voltage toggle between the specified values?
4-0 VGo to Step 15Go to Step 16
15Replace the PCM.
NOTE: The replacement PCM must be programmed.
Refer to
UBS 98model year Immobilizer Workshop
Manual.
Is the action complete?ÐVerify repairÐ
16Replace faulty or missing camshaft magnet.
Is the action complete?
ÐVerify repairÐ

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±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±234
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0502 VSS Circuit Low Input
D06RW019
Circuit Description
The vehicle speed sensor has a magnet rotated by the
transmission output shaft. Attached to the sensor is a hall
effect circuit the interacts with the magnetic field treated
by the rotating magnet. A 12-volt operating supply for the
speed sensor hall circuit is supplied from the meter fuse.
The VSS pulses to ground the 9-volt signal sent from the
powertrain control module (PCM) on the reference circuit.
The PCM interprets vehicle speed by the number of
pulses to ground per second on the reference circuit.
Conditions for Setting the DTC

Engine is running.

Engine coolant temperature is above 60
C (140
F).

Engine speed is between 1800 RPM and 2500 RPM.

Throttle angle is between 10% and 40%.

Engine load is greater than 50 kPa.

MAP sensor indicates greater than 50 kPa manifold
pressure.

PCM detects no VSS signal for 12.5 seconds over a
period of 25 seconds.
Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.

The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC

DTC P0502 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
10. To avoid backprobing the VSS and possibly
damaging a seal or terminal, the VSS output can be
tested at the point where the transmission harness
connects to the engine harness. Power and ground
are applied by jumpers to the VSS through the
connectors which are located just in front of the air
cleaner assembly. The VSS signal is monitored
with a DVM as the rear driveshaft turns. The
wheels can be turned to rotate the driveshaft, or in
2-wheels-drive vehicles the driveshaft can be turned
directly.
12. The speedometer-to-PCM VSS signal wire is
spliced to a wire leading to the cruise control
module. If a short to ground or voltage is indicated
between the PCM and speedometer, it could be on
the cruise control circuit if the vehicle is equipped
with cruise control.

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