2007 ISUZU KB P190 engine

ENGINE DRIVEABILITY AND EMISSIONS 6E–195
DIAGNOSTIC TROUBLE CODE (DTC) P0502 VEHICLE SPEED SENSOR (VSS) CIRCUIT LOW INPUT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The vehicle speed sensor has a magnet rotated by the
transmission output shaft. Attached to the sensor is a
hall effect circuit that interacts with the magnetic field
created by the rotating magnet. A 12-volt operating
supply for the speed sensor hall circuit is supplied from
the meter fuse.
Diagnostic Aids
• Poor connection at ECM: Inspect harness connectors for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0502 B Vehicle Speed Sensor Circuit Low Input 1. No DTC relating to MAP sensor, TPS, ECT
sensor, injector control circuit and ignition
control circuit.
2. Engine is running.
3. Vehicle speed is below 3km/h in power condition or 2km/h in deceleration condi-
tion. ECM uses 0km/h condition as substitute.

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ISUZU KB P190 2007

6E–196 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0502 Vehicle Speed Sensor Circuit Low Input
StepAction Value(s) Yes No
1 Was the “On-Board Diagnostic (OBD) System Check” performed?
—Go to Step 2Go to
On Board
Diagnostic
(OBD) System Check
2 1. Connect the Tech 2. 2. Review and record the failure information.
3. Select “F0: Read DTC Infor By Priority” in “F0: Diagnostic Trouble Code”.
Is the DTC P0502 stored as “Present Failure”? — Go to Step 3Refer to
Diagnostic Aids and Go to Step
3
3 1. Using the Tech2, ignition “On” and engine “Off”. 2. Select “Clear DTC Information” with the Tech2 andclear the DTC information.
3. Operate the vehicle and monitor the “F5: Failed This Ignition” in “F2: DTC Information”.
Was the DTC P0502 stored in this ignition cycle? — Go to Step 4Refer to
Diagnostic Aids and Go to Step
4
4 Check for poor/faulty connection at the VSS, meter, immobilizer control unit (if equipped), ECM and other
connectors. If a poor/faulty connection is found, repair
the faulty terminal.
Was the problem found?
— Verify repair Go to Step 5
5 Remove the VSS from the housing case and visually check.
Was the problem found? — Go to Step 19Go to Step 6
6 8
23
27
910
C-56(J2)
B-68
B-24
E-44

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–197
6 Using the DVM and check the VSS signal.1. Ignition “On”, vehicle “Run (lift up)”.
2. Measure the VSS output voltage at sensor, meter, immobilizer control unit (if equipped) and ECM.
Does the tester indicate specified value?
If a oscilloscope is available, monitor the VSS signal.
Does the oscilloscope indicate correct wave form?
Refer to
Diagnostic Aids
and Go to Step
21 Refer the table
7 Using the DVM and check the VSS power supply circuit.
1. Ignition “On”, engine “Off”.
2. Disconnect the VSS connector.
3. Check the circuit for open or short to ground circuit.
Was the DVM indicated specified value?
10 - 14.5V Go to Step 9Go to Step 8
8 Repair the open circuit between the VSS and meter fuse.
Is the action complete? — Verify repair —
Step
Action Value(s) Yes No
Measurement Position Voltage (V)
(AC Range)If No
Good
VSS terminal 3 & GND Approximately 7.0 V at 20km/hGo to
Step 7
Meter B24 connector 9 &
GND Go to
Step 11
Meter B24 connector 10 &
GND Go to
Step 13
Immobilizer control unit B68
connector 6 & GND Go to
Step 14
Immobilizer control unit B68
connector 8 & GND Approximately
6.5V at 20km/h Go to
Step 16
ECM C56 (J2) connector 23 &
GND Go to
Step 17
Vehicle Speed Sensor (VSS) Reference Wave Form








CH1
0V


CH2
0V




Measurement Terminal: CH1: ECM J2-23(+) / CH2: VSS 3(+)
GND(-)
Measurement Scale: CH1: 10V/div / CH2: 10V/div 50ms/div
Measurement Condition: Approximately 20km/h
Note: The vehicle is without immobilizer system,
CH1 signal is same as CH2.
V
E-44
1

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ISUZU KB P190 2007

6E–198 ENGINE DRIVEABILITY AND EMISSIONS
9 Using the DVM and check the VSS ground circuit.1. Ignition “On”, engine “Off”.
2. Disconnect the VSS connector.
3. Check the circuit for short to power supply circuit.
Was the DVM indicated specified value?
Less than 1V Go to Step 10Repair faulty
harness and verify repair
10 Using the DVM and check the VSS ground circuit. 1. Ignition “Off”, engine “Off”.
2. Disconnect the VSS connector.
3. Check the circuit for open circuit.
Was the problem found?
—Repair faulty
harness and verify repair Go to Step 19
11 Using the DVM and check the VSS signal circuit. 1. Ignition “On”, engine “Off”.
2. Disconnect the VSS connector and meter connector.
3. Check the circuit for short to power supply circuit.
Was the DVM indicated specified value?
Less than 1V Go to Step 12Repair faulty
harness and verify repair
Step Action Value(s) Yes No
V
E-44
2
E-44 2
V
B-24
9

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–199
12 Using the DVM and check the VSS signal circuit.1. Ignition “Off”, engine “Off”.
2. Disconnect the VSS connector and meter connector.
3. Check the circuit for open or short to ground circuit.
If a open or short to ground circuit is found, repair the
faulty harness and verify repair.
Is the action complete?
—Verify repair —
13 Replace the speed meter. Is the action complete? — Verify repair —
14 Using the DVM and check the VSS signal circuit. 1. Ignition “On”, engine “Off”.
2. Disconnect the meter connector and immobilizer control unit connector (if equipped).
3. Check the circuit for short to power supply circuit.
Was the DVM indicated specified value?
Less than 1V Go to Step 15Repair faulty
harness and verify repair
15 Using the DVM and check the VSS signal circuit. 1. Ignition “Off”, engine “Off”.
2. Disconnect the meter connector and immobilizer control unit connector (if equipped).
3. Check the circuit for open or short to ground circuit.
If a open or short to ground circuit is found, repair the
faulty harness and verify repair.
Is the action complete?
—Verify repair —
Step
Action Value(s) Yes No
B-24
9E-443
V
B-68
6
B-24 10B-68
6

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ISUZU KB P190 2007

6E–200 ENGINE DRIVEABILITY AND EMISSIONS
16 Replace the immobilizer control unit (if equipped). Is the action complete? — Verify repair —
17 Using the DVM and check the VSS signal circuit. 1. Ignition “Off”, engine “Off”.
2. Disconnect the immobilizer control unit connector (if equipped) and ECM connector.
3. Ignition “On”.
4. Check the circuit for short to power supply circuit.
Was the DVM indicated specified value?
Less than 1V Go to Step 18Repair faulty
harness and verify repair
18 Using the DVM and check the VSS signal circuit. Breaker box is available:
1. Ignition “Off”, engine “Off”.
2. Install the breaker box as type A. (ECM disconnected) Refer to 6E-88 page.
3. Disconnect the immobilizer control unit connector (if equipped).
4. Check the circuit for open or shot to ground circuit.
Was the problem found?
Breaker box is not available:
1. Ignition “Off”, engine “Off”.
2. Disconnect the immobilizer control unit connector (if equipped) and ECM connector.
3. Check the circuit for open or short to ground circuit.
Was the problem found?
—Repair faulty
harness and verify repair Go to Step 21
19 Substitute a known good VSS and recheck. Was the problem solved? — Go to Step 20Go to Step 21
Step
Action Value(s) Yes No
V
C-56(J2)
23
J2-32Breaker BoxB-687
ΩΩ
B-68
C-56(J2)
23
8

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–201
20 Replace the VSS. Was the problem solved? — Verify repair Go to Step 21
21 Is the ECM programmed with the latest software release?
If not, download the latest software to the ECM using
the “SPS (Service Programming System)”.
Was the problem solved? — Verify repair Go to Step 22
22 Replace the ECM. Is the action complete?
IMPORTANT: The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual.
Following ECM programming, the immobilizer system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobilizer System-ECM replacement” for
the ECM/Immobilizer linking procedure. — Verify repair —
Step
Action Value(s) Yes No

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ISUZU KB P190 2007

6E–202 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0562 SYSTEM VOLTAGE LOW
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The engine control module (ECM) monitors the system
voltage on the ignition feed terminal to the ECM. A
system voltage Diagnostic Trouble Code will set
whenever the voltage is below a calibrated value.
Diagnostic Aids
• If the Diagnostic Trouble Code sets when an accessory is operated, check for a poor connection or
excessive current draw.
• Check for open circuits or shorts to ground on the ECM’s battery or ignition inputs.
Diagnostic Trouble Code (DTC) P0562 System Voltage Low
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0562 D System Voltage Low Battery voltage is below 11V.No fail-safe function.
StepAction Value(s) Yes No
1 Was the “On-Board Diagnostic (OBD) System Check” performed?
—Go to Step 2Go to
On Board
Diagnostic
(OBD) System Check

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ISUZU KB P190 2007