2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 1360

2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 1360

Fuel Tank Pressure Sensor Replacement (See: Powertrain Management/Computers and Control Systems/Fuel Tank Pressure Sensor/Service and

Repair)

P0451

DTC P0450 or P0451 (LAU)

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 P0450

- Fuel Tank Pressure Sensor Circuit

DTC P0451

- Fuel Tank Pressure Sensor Performance

Typical Scan Tool Data

Circuit/System Description

The control module monitors the fuel tank pressure sensor signal in order to detect vacuum decay and excess vacuum during the evaporative

emission (EVAP) diagnostic test. The control module supplies a 5-volt reference and a low reference circuit to the fuel tank pressure sensor. This

DTC sets if the engine control module (ECM) detects one of the following conditions:

* The fuel tank pressure sensor signal voltage is not within a calibrated range on a cold start-up.

* The fuel tank pressure sensor signal oscillates greater than a calibrated amount when vehicle speed is within a predetermined range.

The following table illustrates the relationship between fuel tank pressure sensor signal voltage and the EVAP system pressure/vacuum.

Conditions for Running the DTC

P0450

* DTC P0100, P0101, P0102, P0103, P0116, P0117, P0118, P0119, P0443, P0449, P0458, P0459, P0498, P0499, P050A, P0506, P0507,

P0700, P2227, P2228, or P2229 is not set.

* The engine is operating.

* The ambient air temperature is greater than -7掳C (+19掳F).

* The vehicle speed is less than 31 km/h (19 mph).

* The ECM has commanded the EVAP canister vent valve open for greater than 3 seconds, 4 seconds for LLT.

* DTC P0450 runs continuously once the above conditions are met for approximately 25 seconds.

P0451 Condition 1

* DTC P0100, P0101, P0102, P0103, P0116, P0117, P0118, P0119, P0443, P0449, P0458, P0459, P0498, P0499, P050A, P0506, P0507,

P0700, P2227, P2228, or P2229 is not set.

* The engine is operating for greater than 1 second.

* The engine is idling.