2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 1358
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.
* The ambient air temperature is greater than -7掳C (+19掳F).
* The vehicle speed is less than 10 km/h (6 mph) for greater than 29 seconds.
* The BARO is greater than 68 kPa.
* The fuel level is between 11-88 percent.
* The ECM has commanded the EVAP canister purge solenoid ON.
* The ECM has commanded the EVAP canister vent valve closed for greater than 4 seconds.
* DTC P0451 runs continuously when the above conditions are met for approximately 25 seconds.
P0451 Condition 2
* 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 BARO is greater than 68 kPa.
* The fuel level is between 11-88 percent.
* The ECM has commanded the EVAP canister purge solenoid OFF.
* The ECM has commanded the EVAP canister vent valve open.
OR
* The fuel level is less than 60 percent, 73 percent for LLT.
* The vehicle speed is between 10-76 km/h (6-47 mph) for greater than 30 seconds.
* The ECM has commanded the EVAP canister purge solenoid ON.
OR
* The calculated ambient air temperature is between 4-35掳C (39-95掳F) for greater than 3 seconds.
* DTC P0451 runs continuously when the above conditions are met for approximately 7 seconds.
Conditions for Setting the DTC
P0450
The ECM detects that the FTP sensor signal oscillates greater than 6.09 mm/Hg (3.26 in. H2O) for 4 seconds, or for a cumulative of 30 seconds.
P0451
* The ECM detects that the fuel tank pressure is less than -26.2 mm/Hg (-14.1 in. H2O) or greater than 11.0 mm/Hg (5.9 in. H2O) for 4
seconds or for a cumulative of 30 seconds.
OR
* The ECM detects a change in the zero point of fuel tank pressure sensor signal greater than +/-5.16 mm/Hg (2.76 in. H2O) from the zero
point at start up for 4 seconds, or a cumulative of 30 seconds.
Action Taken When the DTC Sets
