Isuzu N-Series. Manual - part 692
6E-190 Engine Control System (4HK1)
P0501 (Flash Code 25)
Circuit Description
The vehicle speed sensor (VSS) is used by the engine
control module (ECM) and speedometer, which
generates a speed signal from the transmission output
shaft. The VSS has the following circuits.
• Ignition voltage feed circuit
• VSS signal circuit
• VSS low reference circuit
The VSS uses a hall effect element. It interacts with the
magnetic field created by the rotating magnet and
outputs square wave pulse signal. The ECM calculates
the vehicle speed by the VSS. If the ECM detects VSS
signals are changed sharply, this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.
• The ignition voltage is more than 18 volts.
Condition for Setting the DTC
• The ECM detects that the VSS signal are changed
larger than a predetermined vehicle speed.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicator
lamp (MIL) when the diagnostic runs and fails.
Condition for Clearing the MIL / DTC
• The ECM turns OFF the MIL when the key is
cycled after a current DTC clears.
• A current DTC clears when the diagnostic runs and
does not fail at next driving cycle.
• A history DTC clears after 20 consecutive driving
cycles without a fault. Or clear with the Tech 2 or
accelerator pedal operation.
Diagnostic Aid
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
• Electrical or magnetic interference may affect
intermittent condition.
DTC P0501 (Flash Code 25)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views
Step
Action
Value(s)
Yes
No
1
Did you perform the Diagnostic System Check –
Engine Controls?
—
Go to Step 2
Go to Diagnostic
System Check –
Engine Controls
2
1.
Inspect all of the circuits going to the vehicle
speed sensor (VSS) for the following:
• Routed too closely to fuel injection wiring
or components
• Routed too closely to after-market add-
on electrical equipment
• Routed too closely to solenoids, relays,
and motors
2.
If you find incorrect routing, correct the
harness routing.
Did you find and correct the condition?
—
Go to Step 7
Go to Step 3
3
1.
Turn OFF the ignition.
2.
Disconnect the VSS harness connector.
3.
Inspect for an intermittent and for poor
connections at the harness connector of the
VSS (pins 1, 2 and 3 of J-32 connector).
4.
Repair the connection(s) as necessary.
Did you find and correct the condition?
—
Go to Step 7
Go to Step 4