P0452

P0452-NVLD PRESSURE SWITCH STUCK CLOSED

P0452-NVLD Pressure Switch Stuck Closed:

WHEN MONITORED
Immediately after the engine has been started.

SET CONDITION
The PCM activates the NVLD Solenoid. If PCM does not see NVLD switch open an error is detected. Two Trip Fault. Three good trips to turn off the MIL.

POSSIBLE CAUSES
- (K52) EVAP purge solenoid control circuit shorted to ground
- (K107) NVLD switch signal circuit shorted to ground
- NVLD assembly
- EVAP purge solenoid
- PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. VEHICLE HISTORY AND SERVICE BULLETIN INVESTIGATION

Ignition on, engine not running.
With a scan tool, read DTCs and record the related Freeze Frame data if any DTCs are present.
Whether or not any DTCs are present you will want to check the following items which may assist in repairing the customer's complaint successfully.
Check the vehicles repair history.
If the vehicle has a repair history that pertains to the customer's current complaint, review the repair.
Inspect the vehicle for any aftermarket accessories that may have been installed incorrectly.
Check for any service bulletin(s) related to the customer's complaint or DTCs.
If a service bulletin applies, follow the instructions.

Choose the following scenario that best applies.

The service bulletin repaired the customer's complaint.
Testing complete.

A DTC is present, no service bulletins apply, or the service bulletin didn't repair the customer's complaint.
Go To 2

2. ACTIVE DTC

Ignition on, engine not running.
With a scan tool, read DTCs.

Q: Is the DTC active at this time?

YES: Go To 3
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Component Tests and General Diagnostics
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test




3. EVAP PURGE SOLENOID OPERATION

Turn the ignition off.
Disconnect the EVAP Purge Solenoid harness connector.
Ignition on, engine not running.
Using a 12-volt test light, jump across the EVAP Purge Solenoid harness connector.
With the scan tool, actuate the EVAP Purge Solenoid.

Q: Does the test light flash on and off?

YES: Go To 4
NO: Go To 8

4. EVAP PURGE SOLENOID LEAKS/STUCK OPEN

Turn the ignition off.
Connect the EVAP Purge Solenoid harness connector.
Disconnect the vacuum hoses at the EVAP Purge Solenoid.

NOTE: After disconnecting the EVAP Purge Solenoid vacuum connections, inspect the lines and solenoid for any signs of contamination from the EVAP Canister. This may indicate a faulty check valve. Replace/repair as necessary.

Using a hand vacuum pump, apply 10 in Hg to the "CAN" of the EVAP Purge Solenoid.

NOTE: Monitor the vacuum gauge for at least 15 seconds.

Q: Does the EVAP Purge Solenoid hold vacuum?

YES: Go To 5
NO: Replace the EVAP Purge Solenoid. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

5. NVLD SWITCH OPERATION

Ignition on, engine not running.
Using the scan tool, monitor the NVLD Switch State with the vacuum pump still installed and holding vacuum.

Q: Does the scan tool display the NVLD state OPEN?

YES: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Component Tests and General Diagnostics
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 6

NOTE: Remove the vacuum pump and connect the vacuum hose before continuing.

6. NVLD ASSEMBLY

Disconnect the NVLD electrical connector.
Check connectors and clean and repair as needed.

Q: Does the Switch change from CLOSED to OPEN?

YES: Replace the NVLD Assembly. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 7




7. (K107) SIGNAL CIRCUIT SHORTED TO GROUND

Turn the ignition off.
Disconnect the C3 PCM harness connector.
Measure the resistance between ground and the (K107) NVLD Switch Signal circuit in the NVLD Assembly harness connector.

Q: Is the resistance below 100 ohms?

YES: Repair the short to ground in the (K107) NVLD Switch Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 9




8. (K52) EVAP PURGE SOLENOID CONTROL CIRCUIT SHORTED TO GROUND

Turn the ignition off.
Disconnect the C3 PCM harness connector.
Measure the resistance between ground and the (K52) EVAP Purge Solenoid Control circuit in the EVAP Purge Solenoid harness connector.

Q: Is the resistance below 100 ohms?

YES: Repair the short to ground in the (K52) EVAP Purge Sol Control circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 9

9. PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Q: Were there any problems found?

YES: Repair as necessary. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Replace and program the Powertrain Control Module. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test