2010 Cadillac CTS Sedan AWD V6-3.6L Page 1415
6. Remove the EVAP canister. Refer to Evaporative Emission Canister Replacement (See: Powertrain Management/Emission Control
Systems/Evaporative Emissions System/Evaporative Emission Control Canister/Service and Repair).
7. Inspect the EVAP vent solenoid valve circuits in the fuel tank harness, between the EVAP vent solenoid valve connector and X-420 for the
following conditions, and repair as necessary:
* Damaged wiring or terminals
* Open circuits
* Short to ground
* Wire to wire short
8. If all circuits/connections test normal, test or replace the EVAP vent solenoid valve.
Component Testing
1. Test for 20-24 ohm between the terminals of the EVAP vent solenoid valve.
瀚慖f not within the specified range, replace the EVAP vent solenoid valve.
2. Measure the resistance between each terminal of the EVAP vent solenoid valve and the EVAP vent solenoid valve housing. The DMM
should display OL.
瀚慖f not the specified value, replace the EVAP vent solenoid valve.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Evaporative Emission Canister Vent Solenoid Valve Replacement (See: Powertrain Management/Emission Control Systems/Evaporative
Emissions System/Evaporative Emission Control Canister/Canister Vent Valve/Service and Repair)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup, and programming
P0450
DTC P0450 or P0451 (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 P0450
- Fuel Tank Pressure (FTP) Sensor Circuit
DTC P0451
- Fuel Tank Pressure (FTP) Sensor Performance
Typical Scan Tool Data
Circuit/System Description
The control module monitors the fuel tank pressure (FTP) 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 FTP sensor. This DTC sets if the
