Evaporative Emission Control System Diagnosis. GMC Truck Savana 2000

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2000 🢒 Savana 🢒 Engine 🢒 Engine Controls - 5.0L and 5.7L 🢒 Evaporative Emission Control System Diagnosis

Engine Controls Components
Cell 21: EGR and EVAP Controls
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
VCM Connector End Views
Power Distribution Schematics

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 evaporative leak detection diagnostic strategy is based on applying a vacuum to the EVAP system and monitoring the vacuum decay rate. The VCM monitors the vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid turn ON, allowing the engine vacuum to draw a small vacuum on the entire evaporative emission system. If a sufficient vacuum level cannot be achieved, a large leak or a malfunctioning EVAP system malfunction is indicated. The following conditions can cause this problem:

•	A disconnected or malfunctioning fuel tank pressure sensor

•	A missing, malfunctioning, improperly installed, or loose fuel cap

•	A disconnected, damaged, pinched, or blocked EVAP purge line

•	A disconnected or damaged EVAP vent hose

•	A disconnected, damaged, pinched, or blocked fuel tank vapor line

•	A disconnected or malfunctioning EVAP purge solenoid

•	A disconnected or malfunctioning EVAP vent solenoid

•	An open ignition feed circuit to the EVAP vent or purge solenoid

•	A damaged EVAP canister

•	A leaking fuel sender assembly O-ring

•	A leaking fuel tank or fuel filler neck

Any of the above conditions can set a DTC P0440.

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 system voltage is between 10 and 17 volts

•	The fuel level is between 12.5 percent and 87 percent.

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

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

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

1.5°C when the IAT is more than the ECT or

8°C when the ECT is more than the IAT

•	The BARO is more than 73 kPa

Conditions for Setting the DTC

The EVAP system is unable to generate a vacuum more than a calibrated value over a specified period of time.

Action Taken When the DTC Sets

•	The VCM illuminates the MIL during the second key cycle in which the diagnostic reports a fail.

•	The VCM stores the conditions that were present when the DTC sets as a Freeze Frame and Fail Records data.

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

Important: An accurate indication of fuel level is required for the VCM to properly pass or fail this DTC. Always diagnose fuel level sensor DTCs before performing this DTCs diagnostic table. Always check for fuel level sensor DTCs ` stored in history.

Check for the following conditions:

•	A loose, missing, damaged, incorrect or improperly installed fuel cap

•	Missing or damaged O-rings at EVAP canister fuel vapor and purge line fittings

•	A cracked or punctured EVAP canister

•	A damaged or disconnected EVAP purge line, vent hose or fuel tank vapor line

•	Incorrectly routed or defective EVAP system purge and vapor lines

•	A poor connection at the VCM: Inspect the harness connectors for the following conditions:

-	Backed out terminals

-	Improper mating

-	Broken locks

-	Improperly formed or damaged terminals

-	poor terminal to wire connection

•	A damaged harness: Inspect the wiring harness to the EVAP vent solenoid, EVAP purge solenoid and the fuel tank pressure sensor for an intermittent, open or short circuit

•	A kinked, pinched or plugged EVAP purge or fuel tank vapor line. Verify that the lines are not restricted

Refer to Evaporative Emission System Cleaning before starting repairs.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description

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

Inspect the service port. Ensure that the valve core is not damaged. If you suspect the service port of leakage, use the following procedure:

Disconnect the purge line from the evaporative emissions (EVAP) purge solenoid valve.

Connect a hand vacuum pump to the service port by placing the hose and adaptor over the unthreaded end portion of the service port.

Apply vacuum to 5 inches Hg. If the vacuum does not hold, replace the entire purge line that contains the service port.

If the vehicle passes the Service Bay Test, then an intermittent leak or restriction has occurred. Check the fuel tank cap for a possible loose or off condition that may have caused this DTC to set.

If you cannot run the Service Bay Test, proceed to step 5. If there is no fault present, the diagnostic table steps will return you to step 3.

For proper setup and adjustment procedures, refer to the information that is supplied with the EVAP pressure and purge diagnostic cart.

With pressure applied, you may need to disconnect the EVAP lines at the components in order to verify that a line or component is not restricted. A restriction would prevent a vacuum, or would prevent the step 9 test pressure from forming in the fuel tank.

An EVAP pressure sensor that does not correctly respond to vacuum or to pressure will cause this DTC to set.

The EVAP pressure sensor monitors a range from 7.5 inches H2O of pressure to -17.5 inch H2O of vacuum.

Step

Action

Values

Yes

Did you perform the Powertrain On-board Diagnostic (OBD) System check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Check for DTCs P0440, P0442, P0446, P0452, P0453, P0461, P0462, P0463 and P1441.

Are any of the above EVAP system DTCs stored in HISTORY?

Go to the DTCs that are set

Go to Step 3

Inspect the EVAP system for the following conditions:

•	A fuel tank cap that is:

Loose

Incorrect

Defective

Missing

•	EVAP system purge lines that are:

-	Improperly routed

Kinked

Damaged

•	A damaged EVAP system component.

•	A port dust cap and/or schrader valve that are:

Loose

Missing

Damaged

•	Refer to the test descriptions for more information.

Repair the EVAP system if needed.

Did you make a repair to the EVAP system?

Go to Step 25

Go to Step 4

Important: : Before proceeding with the Service Bay Test the vehicle must meet the following operating criteria:

•	Clear DTC Information.

•	Battery voltage that is between 10.5 volts and 17.5 volts.

•	A fuel level that is between 15 percent and 85 percent.

•	Key ON engine temperature that is less than 80°C (176°F).

If any of the above conditions are not met, the scan tool will display Test Aborted when you activate the Service Bay Test.

Record the data stored that is stores when the DTC set, and clear the codes.
Use the scan tool in order to perform the Service Bay Test for the EVAP system.

Does the vehicle pass the Service Bay Test?

Condition not present. Go to Test Description and Diagnostic Aids

Go to Step 5

Turn OFF the ignition.
Connect a vacuum gauge that is set to in Hg directly to the purge connection of the EVAP purge solenoid valve.
Start and idle the engine.
Use a scan tool in order to command the EVAP purge solenoid valve to 100 percent purge.

Is the vacuum at or above the specified value?

12 in Hg

Go to Step 6

Go to Step 11

Turn OFF the ignition.
Disconnect the fuel tank vapor and the EVAP purge line from the EVAP vapor canister.
Plug the canister fitting for the fuel tank vapor line.
Connect a hand vacuum pump to the EVAP purge line canister fitting.
With the ignition ON, command the EVAP vent valve ON, or closed, with the scan tool.
Use the hand vacuum pump in order to apply vacuum up to the specified value.

Can the specified value be obtained and held?

5 in Hg

Go to Step 9

Go to Step 7

Leave system connected as in Step 6.
Disconnect the vent line at the EVAP vent valve.
Plug the vent line.
Use the hand vacuum pump in order to apply vacuum up to the specified value.

Can you obtain and hold the specified value?

5 in Hg

Go to Step 15

Go to Step 8

Inspect the EVAP vent line from the canister to the EVAP vent valve for leaks.
Replace if necessary.

Did you fine and repair a problem?

Go to Step 25

Go to Step 21

Important: The following steps require the EVAP pressure and purge diagnostic station J 41413 and the ultrasonic leak detector J 41416 .

Before you proceed with the diagnosis, always zero the EVAP pressure and vacuum , set to in Hg, on the EVAP pressure/purge diagnostic station.

Turn OFF the ignition.
Remove the plug and the remove the hand vacuum pump.
Reconnect the EVAP vapor canister purge and tank vent lines.
Connect the EVAP pressure/purge diagnostic station J 41413 to the EVAP system service port.
Use a scan tool in order to command the EVAP vent valve Closed.

Important: Do NOT apply more than 15 in H2O of pressure to the EVAP system.

Continuously attempt to pressurize the EVAP system by leaving the EVAP pressure and purge diagnostic station control knob in the pressurize position.
Use the ultrasonic leak detectorJ 41416 in order to locate and repair the EVAP system leak.

Did you find and repair a leak?

Go to Step 25

Go to Step 10

Check the EVAP system for restrictions. Refer to the test description.
Repair as necessary.

Did you find and repair a problem found?

Go to Step 25

Go to Step 22

Turn ON the ignition, leaving the engine OFF. Disconnect the EVAP purge solenoid valve connector.
Connect a test lamp between the purge solenoid ignition feed circuit and a known good engine ground.

Is the test lamp ON?

Go to Step 12

Go to Step 13

Connect the test lamp between the EVAP solenoid ignition feed circuit and the EVAP solenoid control circuit.
Use the scan tool in order to command the EVAP solenoid ON.

Is the test lamp ON?

Go to Step 19

Go to Step 14

Check for and repair the cause of no power to the EVAP purge solenoid ignition feed circuit.
Possible causes of no power include the following conditions:

•	An open ignition feed circuit

•	A shorted ignition feed circuit

•	A shorted EVAP purge solenoid

•	No power to EVAP purge solenoid fuse, caused by an open maxi fuse, or by a fuse link.

Is the repair complete?

Go to Step 25

Inspect the EVAP purge solenoid control circuit for an open condition.
Repair the circuit as necessary.

Did you find and repair a problem?

Go to Step 25

Go to Step 24

Turn ON the ignition, with the engine OFF. Disconnect the EVAP canister vent valve connector.
Connect a test lamp between the EVAP canister vent valve ignition feed circuit and ground.

Is the test lamp ON?

Go to Step 16

Go to Step 17

Connect the test lamp between the EVAP canister vent valve ignition feed circuit and the EVAP canister vent valve control circuit.
Use the scan tool in order to command the EVAP canister vent valve ON.

Is the test lamp ON?

Go to Step 20

Go to Step 18

Check for and repair the cause for no power to the EVAP canister vent valve ignition feed circuit.
Possible causes include the following conditions:

•	An open ignition feed circuit

•	A shorted ignition feed circuit

•	A shorted EVAP canister vent valve

•	No power to EVAP canister vent valve fuse, caused by an open maxi fuse or by a fuse link.

Is the repair complete?

Go to Step 25

Inspect the EVAP canister vent valve control circuit for an open condition.
Repair the circuit as necessary.

Did you find and repair a problem?

Go to Step 25

Go to Step 24

Important: : Inspect the EVAP purge solenoid valve and the purge line for carbon contamination. Refer to Diagnostic Aids.

Replace the EVAP purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .

Is the replacement complete?

Go to Step 25

Replace the EVAP vent valve. Refer to Evaporative Emission Vent Valve Replacement .

Is the replacement complete?

Go to Step 25

Replace the EVAP Vapor Canister. Refer to Evaporative Emission Canister Replacement .

Is the replacement complete?

Go to Step 25

Relieve all system pressure.
Using the scan tool, use the Purge/Seal function in order to turn ON the EVAP purge solenoid valve to varying vacuum levels. With the engine running, quickly SEAL the system with the scan tool. Leaving the EVAP purge solenoid valve ON for higher percents or for longer time periods will allow more vacuum to develop. You can apply a maximum of 8.5 in H2O of vacuum to the EVAP system using the scan tool.
While the system is sealed, compare the EVAP pressure and purge diagnostic stations vacuum gauge, set to in H2O, to the vacuum shown on the scan tool from the EVAP fuel tank pressure sensor. Allow a few seconds for the system to stabilize.

Do the values indicate the same amount of vacuum in the EVAP system to within the specified range?

2 in H2O

Go to Step 3

Go to Step 23

Replace the fuel tank pressure sensor. Refer to Fuel Tank Pressure Sensor Replacement .

Is the replacement complete?

Go to Step 25

Important: The replacement VCM must be programmed.

Replace the VCM. Refer to VCM Replacement/Programming .

Is the action complete?

Go to Step 25

Use the scan tool in order to clear the DTCs.
Start the engine.
Allow the engine to idle until the engine reaches the normal operating temperature.
Select DTC and the Specific DTC function.
Enter the DTC number which was set.
Operate the vehicle, with the Conditions for Setting this DTC, until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

Go to Step 26

Does the scan tool display any additional undiagnosed DTCs?

Go to applicable DTC table

System OK