Dtc P2127 Or P2128 (Flash Code 122) - Isuzu 2008MY N Series Workshop Manual

1A-262 Engine Control System (4HK1)

DTC P2127 or P2128 (Flash Code 122)

Circuit Description
The accelerator pedal position (APP) sensor is
mounted on the accelerator pedal control assembly.
The sensor is made up of two individual sensors within
one housing. The ECM uses the APP sensors to
determine the amount of acceleration or deceleration
that is desired. The APP sensor 2 has the following
circuits.
• 5 volts reference circuit
• Low reference circuit
• APP sensor 2 signal circuit
The APP sensor 2 provides a signal to the ECM on the
signal circuit, which is relative to the position changes
of the accelerator pedal angle. If the ECM detects an
excessively low or high signal voltage, DTC P2127 or
P2128 will set.
Condition for Running the DTC
• DTCs P060B and P0651 are not set.
• The battery voltage is between 18 to 32 volts.
• The ignition switch is ON.
Condition for Setting the DTC
• The ECM detects that the APP sensor 2 signal
voltage is less than 0.2 volts. (DTC P2127)
• The ECM detects that the APP sensor 2 signal
voltage is more than 4.9 volts. (DTC P2128)
Circuit/ System Testing DTC P2127
Step
Did you perform the Diagnostic System Check
1
- Engine Controls?
1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
2
4. Monitor the DTC Information with a scan tool.
Is DTC P0651 also set?
Fully depress and release the accelerator pedal
while observing the Accelerator Pedal Position
(APP) Sensor 2 parameter with a scan tool.
3
Does the scan tool indicate less than the
specified value during depressing or releasing
the pedal?
Action
Action Taken When the DTC Sets
• The ECM illuminates the MIL on the second
consecutive driving cycle when the diagnostic runs
and fails. Refer to DTC Type Definitions for Action
Taken When the DTC Sets - Type B. (Euro 4
specification)
• The ECM illuminates MIL when the diagnostic runs
and fails. Refer to DTC Type Definitions for Action
Taken When the DTC Sets - Type A. (Except Euro
4 specification)
• The ECM blinks the exhaust brake indicator lamp
when the diagnostic runs and fails.
• The ECM limits fuel injection quantity.
• The ECM inhibits exhaust brake control.
Condition for Clearing the DTC
• Refer to DTC Type Definitions for Condition for
Clearing the MIL/ DTC - Type B. (Euro 4
specification)
• Refer to DTC Type Definitions for Condition for
Clearing the MIL/ DTC - Type A. (Except Euro 4
specification)
Diagnostic Aids
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Value(s) Yes
—
Go to Step 2
—
Go to DTC P0651
0.2 volts
Go to Step 4
No
Go to Diagnostic
System Check -
Engine Controls
Go to Step 3
Go to Diagnostic
Aids