Dtc25 - Vehicle Speed Sensor System Fault - Isuzu 4HL1 Workshop Manual

1A-116 Engine Control System

DTC25 - Vehicle Speed Sensor System Fault

0.5
R/B
PTO Sensor
Circuit Description
The VS (vehicle speed) sensor is equipped with a Hall
effect circuit. The magnet installed to the transmission
output shaft is rotated together with the shaft to
generate a magnetic field. This Hall effect sensor
interacts with the magnetic field and generates and
sends a signal to the VIM. The VS sensor is energized
via meter fuse. The VIM uses the VS signal pulses to
judge the vehicle speed.
DTC25 will be set when the VIM does not receive the
VS signal under the running conditions (clutch
engaged).
Major Faulty Event
• Improper speedometer indication
• Poor driveability
Conditions for Setting the DTC
The state where clutch and neutral switches are in
normal condition, the automatic transmission or clutch
switch is turned off, the engine is running at 2200 rpm
or more, the neutral switch is turned off, and the vehicle
speed is 0 km/h lasts 5 seconds.
Action Taken When the DTC Sets
• After the DTC is set, the ECM will illuminate the
CHECK ENGINE lamp (MIL).
34 31 71
0.5 0.5
Y Y/BR
30
0.5
Y/G
Idling
Control
Conditions for Clearing MIL/DTC
When the system fails and the DTC is stored to the
ECM, even repairing the faulty portion will not clear the
DTC from the memory. To clear the DTC, conduct the
following steps.
1. Turn off the idle position switch for not less than 1
second but not more than 3 seconds. (Press the
accelerator pedal.)
2. Turn on the idle position switch for not less than 1
second but not more than 3 seconds. (Release the
accelerator pedal.)
3. Turn off the idle position switch for not less than 1
second but not more than 3 seconds. (Press the
accelerator pedal.)
4. Turn on the idle position switch for not less than 1
second but not more than 3 seconds. (Release the
accelerator pedal.)
5. Turn off the idle position switch for not less than 1
second but not more than 3 seconds. (Press the
accelerator pedal.)
6. After the above operations are properly completed,
the CHECK ENGINE lamp (MIL) illuminates for 3
seconds to report the memory is cleared.
7. Turn off the starter switch. Wait for 5 seconds and
turn on the starter switch again.
When Tech 2 has been connected to the vehicle, the
DTC can be cleared through the memory clear
operation with Tech 2.
VIM
(Vehicle
Interface
Module)
VS Sensor
LNW21AMF007801-X