Dodge Caliber. Manual - part 772

Theory of Operation

The Evap Purge Monitor tests the integrity of the hoses/tube between the throttle body/intake and the fuel tank. The
monitor is a two stage test and runs only after the Evap system passes the small leak test. Stage one is non-
intrusive. The PCM monitors the purge vapor ratio and the ESM switch closed ratio. If the purge vapor ratio is
above a calculated value, the monitor passes. If the ESM switch closed ratio is greater than calculated value when
purge flow is greater than a minimum value, the monitor passes. Stage two is an intrusive test and runs only if
stage one does not pass. The PCM commands the purge solenoid to flow at a specified rate to force the purge
vapor ratio to update. The ratio is compared to a calibrated specification. If it is less than specified, a one trip failure
is recorded. This test can detect if the purge hose is off, obstructed, or the purge valve is not operational.

•

When Monitored:
With the engine running, after the Evap System small leak test has passed.

•

Set Condition:
If the PCM detects that the purge vapor ratio and the ESM switch closed ratio are below a calculated value,
the PCM commands the purge solenoid to flow at a specified rate to update the purge vapor ratio. If the ratio
remains below a specified value, a one trip failure is recorded. Two Trip Fault. Three good trips to turn off the
MIL.

Possible Causes

INTERMITTENT DTC

EVAP PURGE SOLENOID VACUUM SUPPLY

EVAP PURGE HOSE/TUBE OBSTRUCTION

EVAP PURGE SOLENOID

POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).

Diagnostic Test

EVAP SYSTEM PRETEST

Ignition on, engine not running.

With a scan tool, select View DTCs. Record the Freeze Frame data if any DTCs are present.

Review the vehicle repair history for items related to the current condition.

Inspect the vehicle for any aftermarket accessories that may have been installed incorrectly.

Check for any related technical service bulletins (TSBs) and, if any apply, follow the recommended procedure.

Select the appropriate response from the list below:

A technical service bulletin (TSB) repaired the condition.

Test complete.

A DTC is present, no TSBs apply, or the TSB did not repair the condition.

Go to 2

DTC IS ACTIVE

NOTE: If P0443 is set along with this DTC, perform the diagnostic procedure for P0443 before continuing
with this test.
Start the engine.

Allow the engine to idle.

Using the scan tool, perform the ESIM FORCED MONITOR TEST. Allow the test to complete.

With a scan tool, select View DTCs.

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NOTE: If any other DTC sets, active or pending, perform the diagnostic procedure for that DTC before pro-
ceeding with this test.

Is the status Active for this DTC?

Yes

>> Go to 3

>> Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE -

DIAGNOSIS AND TESTING)

EVAP SYSTEM INSPECTION

Inspect the EVAP System for any of the following conditions:

- Holes or cracks

- Loose seal points

- Damaged or missing components

- Incorrect routing of hoses and tubes

- Loose or missing Fuel Cap

- Damaged or missing Fuel Cap seal

- Improper installation of the Fuel Cap

- Damaged Locking tabs on the Fuel Cap and/or filler tube

- Damaged seal points on the Fuel Cap and/or filler tube

Were any problems found?

Yes

>> Repair as necessary.

Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

>> Go to 4

INSUFFICIENT VACUUM SUPPLY TO THE EVAP PURGE SOLENOID

Inspect the Evap Purge Solenoid vacuum supply hose for proper routing and installation.

Make sure the vacuum supply hose between the throttle body or intake manifold and the EVAP Purge Solenoid is
free from any obstructions or blockage.

Make sure the vacuum port at the throttle body or intake manifold is free from any obstructions or blockage.

Were any problems found?

Yes

>> Repair as necessary.

Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

>> Go to 5

EVAP PURGE HOSE/TUBE OBSTRUCTION

Inspect the Evap Purge hose/tube for proper routing and installation between the EVAP Purge Solenoid and the
Fuel Tank and between the Fuel Tank and the Evap Purge Canister.

Make sure the hose/tube is not damaged or kinked and is free from any obstructions or blockage.

Were any problems found?

Yes

>> Repair or replace as necessary.

Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

>> Go to 6

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ENGINE ELECTRICAL DIAGNOSTICS - GPEC

EVAP PURGE SOLENOID

NOTE: After disconnecting the Evap Purge Solenoid vacuum connections, inspect the lines and solenoid for
signs of contamination.
Using a hand vacuum pump, apply 10 in Hg to the

CAN

side of the EVAP Purge Solenoid.

NOTE: The solenoid should hold vacuum for a minimum of 15 seconds.
Turn the ignition on.

With the scan tool, actuate the EVAP Purge Solenoid to the ON position.

NOTE: The vacuum should drop when the solenoid is actuated.

Does the solenoid function as described above?

Yes

>> Go to 7

>> Replace the EVAP Purge Solenoid.

Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

POWERTRAIN CONTROL MODULE (PCM)

Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the EVAP Purge Sole-
noid and the Powertrain Control Module (PCM).

Look for any chafed, pierced, pinched, or partially broken wires.

Look for broken, bent, pushed out or corroded terminals.

Refer to any Technical Service Bulletins that may apply.

Were any problems found?

Yes

>> Repair as necessary.

Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

>> Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information.

Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

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P0443-EVAP PURGE SOLENOID CIRCUIT

For a complete wiring diagram Refer to Section 8W

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ENGINE ELECTRICAL DIAGNOSTICS - GPEC

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