DTC P1259 (LPL or LPV)
Diagnostic Instructions
DTC Descriptors
| DTC P1259 11: High Pressure Fuel Pump
Performance |
| DTC P1259 12: High Pressure Fuel Pump
Performance |
Circuit/System Description
The engine control module (ECM) uses commanded fuel pump flow to
determine a desired fuel rail pressure. The ECM monitors fuel rail
pressure with the fuel rail pressure sensor. The Fuel Pressure
Regulator Solenoid 1 is used to control the fuel pressure at the
fuel rail. The Fuel Pressure Regulator Solenoid 1 is pulse width
modulated (PWM). The ECM supplies the voltage directly to the Fuel
Pressure Regulator Solenoid 1. The ECM controls the solenoid by
grounding the control circuit with a solid state device called a
driver.
Conditions for Running the DTC
| • |
The DTCs runs continuously
once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the rail pressure is below the minimum
threshold.
Action Taken When the DTC Sets
| • |
DTC P1259 11 is a Type C
DTC. |
| • |
DTC P1259 12 is a Type B
DTC. |
Conditions for Clearing the DTC
| • |
DTC P1259 11 is a Type C
DTC. |
| • |
DTC P1259 12 is a Type B
DTC. |
Diagnostic Aids
| • |
A restricted fuel supply line,
a leakage in the high pressure section, an activated pressure
limiter, too much or too little fuel in the low pressure line may
cause DTCs to set. When ambient temperatures are below 0°C
(32°F), the fuel tank pickup screen may be iced over from water
in the fuel tank. |
| • |
High resistance in either
circuit of the Fuel Pressure Regulator 1 will cause a DTC to
set. |
| • |
There are no driveability
concerns associated with the fuel rail pressure regulator unless a
DTC is present. One of the causes of these DTCs is a sticking fuel
rail pressure regulator. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
| 1. |
Ignition ON, observe the DTC
information with a scan tool. Verify that no other DTCs are
set. |
| 2. |
Engine running, observe the
scan tool DTC information parameter. DTCs P1259 should not
set. |
| 3. |
Operate the vehicle within the
Conditions for Running the DTC to verify the DTC does not reset.
You may also operate the vehicle within the conditions that you
observed from the Freeze Frame/Failure Records data. |
Circuit/System Testing
| 1. |
Inspect and repair one of the
following conditions: |
| |
• |
Fuel level in fuel tank too
low |
| |
• |
Fuel injection pump stuck
open |
| |
• |
Restricted fuel
injector |
| |
• |
Fuel rail pressure regulator
stuck |
| 2. |
Ignition OFF, disconnect the
harness connector at the G18 High Pressure Fuel Pump. |
| 3. |
Ignition ON, verify a test
lamp illuminates between the ignition voltage circuit terminal 1
and ground. |
| ⇒ |
If the test lamp does not illuminate, repair the
ignition voltage circuit for a short to ground or an open/high
resistance. |
| 4. |
Disconnect the X2 harness
connector at the K20 Engine Control Module. |
| 5. |
Ignition ON, test for less
than 0.3 V between the signal circuit at the harness connector from
G18 High Pressure Fuel Pump terminal 2 and ground. |
| ⇒ |
If greater than the specified range, test the
signal circuit for a short to Voltage. If the circuit tests normal,
replace the K20 Engine Control Module. |
| 6. |
Ignition OFF, test for greater
than 500 kΩ between the signal circuit terminal 2 and
earth. |
| ⇒ |
If less than the specified range, test the signal
circuit for a short to ground. If the circuit tests normal, replace
the K20 Engine Control Module. |
| 7. |
Test for less than 5 Ω
between the signal circuit at the harness connector from G18 High
Pressure Fuel Pump terminal 2 and the signal circuit at the K20
Engine Control Module terminal 5. |
| ⇒ |
If greater than the specified range, test the
signal circuit for an open circuit. If the circuit tests normal,
replace the K20 Engine Control Module. |
| 8. |
If all circuit tests normal,
replace the G18 High Pressure Fuel Pump. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
|
