DTC P1441 Evaporative Emission (EVAP) System Flow During Non-Purge. Chevrolet Tahoe 4WD

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1998 🢒 Tahoe 4WD - RHD 🢒 DTC 🢒 DTC P1441 Evaporative Emission (EVAP) System Flow During Non-Purge

EVAP/PCV - Comp Loc Figure
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The evaporative system includes the following components:

•	The fuel tank

•	The EVAP vent solenoid

•	The fuel tank pressure sensor

•	The fuel pipes and hoses

•	The vapor lines

•	The fuel cap

•	The evaporative emission canister

•	The purge lines

•	The EVAP purge solenoid

The EVAP purge solenoid valve allows the manifold vacuum to purge the canister. The Vehicle Control Module (VCM) supplies a ground in order to energize the solenoid valve (purge ON). The EVAP purge solenoid control by the VCM is Pulse Width Modulated (PWM) or turned ON and OFF several times a second. The duty cycle (pulse width) is determined by the engine operating conditions including the load, the throttle position, the coolant temperature, and the ambient temperature. The duty cycle is calculated by the VCM, and the purge solenoid is commanded ON when certain conditions have been met.

The system checks for conditions that cause the EVAP system to purge continuously by commanding the EVAP vent solenoid ON and the EVAP purge solenoid OFF (EVAP vent solenoid CLOSED, EVAP purge PWM 0%). If the fuel tank pressure level increases during the test, a continuous purge flow condition is indicated. The following items can cause this condition:

•	A leaking EVAP purge solenoid

•	A grounded EVAP purge solenoid driver circuit

Conditions for Running the DTC

•	No active MAP sensor DTCs

•	No active TP sensor DTCs

•	No active VS sensor DTCs

•	No active O2 sensor DTCs

•	No active ECT sensor DTCs

•	No active IAT sensor DTCs

•	DTC P0125 not active

•	The fuel level is between 12.5-88 %

•	The system voltage is between 10-17 volts.

•	The ECT is between 4°C-30°C(39°F-86°F)

•	The IAT is between 4°C-30°C(39°F-86°F)

•	The cold start temperature (ECT minus IAT) is less than

-	1.5°C(35°F) when the IAT is greater than the ECT

-	8°C(46°F) when the ECT is greater than the IAT

•	The BARO is greater than 72.5 kPa

Conditions for Setting the DTC

The EVAP system develops a vacuum greater than a calibrated value when purge is not commanded.

Action Taken When the DTC Sets

The VCM will turn ON the MIL after 2 consecutive driving cycles with the fault active.

Conditions for Clearing the MIL or DTC

•	The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.

•

A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.

•	Use a scan tool in order to clear the DTCs.

Diagnostic Aids

A poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation may cause an intermittent.

Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for the following conditions:

•	Backed out terminals

•	Improper mating

•	Broken locks

•	Improperly formed or damaged terminals

•	Poor terminal to wire connections

•	Physical damage to the wiring harness

Refer to Symptoms .

Test Description

The numbers below refer to the step numbers on the diagnostic table:

Determines if the EVAP Purge Solenoid is leaking.

Determines if the EVAP canister Purge Valve Driver circuit is shorted to ground.

Determines if the EVAP canister Purge Valve Driver circuit wiring or VCM is at fault.

Step	Action	Value(s)	Yes	No
1	Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and the Failure Records for reference. This information will be lost when the Clear DTC Information function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Important: Before continuing with diagnosis, zero the EVAP pressure and vacuum gauges on the Enhanced EVAP Pressure Purge Diagnostic Cart J 41413. Refer to tool operating instructions. Connect the Enhanced EVAP Pressure Purge Diagnostic Cart J 41413 to the EVAP service port. Turn the rotary switch on cart to PURGE. Start the engine. Monitor vacuum with the gauge on the cart. Is vacuum more than the specified value and holding steady?	-15 in.H2O	Go to Step 3	Refer to Diagnostic Aids
3	Turn OFF the ignition. Disconnect the EVAP Purge Solenoid electrical connector. Turn ON the ignition, with the engine OFF. Connect a test lamp to B+ and probe terminal B of the EVAP Purge Solenoid connector. Is the test lamp ON?	--	Go to Step 4	Go to Step 6
4	Turn OFF the ignition. Disconnect the VCM Gray connector. Turn ON the ignition, with the engine OFF. Connect test light to B+ and probe terminal B of the EVAP Purge Solenoid connector. Is the test lamp ON?	--	Go to Step 5	Go to Step 7
5	Repair the short to ground in the EVAP Canister Purge Valve Driver circuit. Refer to Wiring Repairs in Repair Instructions. Is action complete?	--	Go to Step 8	--
6	Replace the EVAP canister purge solenoid. Refer EVAP Canister Purge Solenoid Valve Replacement in Repair Instructions. Is the action complete?	--	Go to Step 8	--
7	Replace the VCM. Program the VCM. Refer to VCM Replacement/Programming . Perform the Crankshaft Variation Learn Procedure. Refer to Crankshaft Position System Variation Learn . Is the action complete?	--	Go to Step 8	--
8	Use the scan tool in order to select the DTC and the Clear DTC Information functions. Perform the Service Bay Test for EVAP. Is action complete?	--	Go to Step 9	--
9	Use the scan tool in order to display the Capture Info and the Review Capture Info functions. Are there any DTCs displayed that have not been diagnosed?	--	Go to applicable DTC table	System OK