2010 Cadillac CTS Sedan AWD V6-3.6L Page 986
Engine idling, command the Fuel Pressure Control to Increase with a scan tool. The Fuel Rail Pressure Sensor parameter should increase with each
command.
If the Fuel Rail Pressure Sensor parameter does not increase with each command, replace the high pressure fuel pump.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Camshaft Removal - Left Side (See: Engine, Cooling and Exhaust/Engine/Service and Repair/Overhaul/36. Camshaft Removal - Left Side)
* Fuel Pump Replacement (See: Powertrain Management/Fuel Delivery and Air Induction/Fuel Pump/Service and Repair)
P0089
DTC P0087, P0088, or P0089 (w/LLT)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0087
- Fuel Rail Low Pressure
DTC P0088
- Fuel Rail High Pressure
DTC P0089
- Fuel Pressure Regulator Performance
Circuit/System Description
The fuel rail pressure sensor detects fuel pressure within the fuel rail. The engine control module (ECM) provides a 5 V reference voltage on the 5
V reference circuit and ground on the low reference circuit. The ECM receives a varying signal voltage on the signal circuit.
High pressure fuel is regulated by the high pressure fuel pump actuator, which is a part of the high pressure fuel pump. The high pressure fuel pump
actuator is a solenoid valve. The ECM provides a voltage on the actuator high control circuit and ground on the actuator low control circuit. Both
circuits are controlled through output drivers within the ECM. When deactivated, both drivers are disabled. When activated, the high control circuit
driver energizes the high pressure fuel pump actuator and the low control circuit driver pulse-width modulates (PWM) the low control circuit to
ground.
The high pressure mechanical fuel pump is driven by three lobes on the camshaft. The ECM uses the camshaft and crankshaft position sensor inputs
to synchronize the high pressure fuel pump actuator with the position of each of the camshaft lobes. The ECM regulates fuel pressure by adjusting
the portion of each pump stroke that provides fuel to the rail.
The ECM monitors the fuel rail fuel pressure sensor and the high pressure fuel pump actuator to determine if the commanded and actual pressure
are within a predetermined range, or if the amount of fuel pressure correction exceeds a calibrated pressure.
Conditions for Running the DTC
* DTC P0090, P0091, P0092, P0191, P0192, or P0193 is not set.
* The ignition 1 signal parameter is between 10-18 V.
* The engine start temperature is greater than -48掳C (-54掳F).
* The fuel level is greater than 11 %.
* The deceleration fuel cut-off (DFCO) is inactive.
* The engine speed is greater than 600 RPM once during engine start for greater than 5 s.
* The air bag is not deployed.
* DTCs P0087, P0088, and P0089 run continuously when the above conditions are met for 5 s.
Conditions for Setting the DTC
