2010 Cadillac CTS Sedan AWD V6-3.6L Page 981

2010 Cadillac CTS Sedan AWD V6-3.6L Page 981

1. Install any components or connectors that have been removed or replaced during diagnosis.

2. Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.

3. Clear the DTCs.

4. Turn OFF the ignition for 60 seconds.

5. Engine running, command skip shift solenoid ON and OFF with a scan tool, while observing the skip shift circuit status parameters. The

circuit status parameters should change from OK to Not Run or Not Run to OK.

瀚慖f another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code

Descriptions/Diagnostic Trouble Code (DTC) List - Vehicle) and perform the appropriate diagnostic procedure.

P0087

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

P0087

The actual fuel rail pressure is 1 MPa (145 psi) less than the desired fuel pressure. The condition exists for greater than 5 s.