How To Test The EVAP Vent Solenoid (2003-2013 Chevrolet Express, GMC Savana)

TEST 2: Making Sure The EVAP Solenoid Is Allowing Fresh Air Intake

Now that you've confirmed that the EVAP vent solenoid is getting power, we no need make sure it's in the 'OFF' position and letting fresh air to pass.

To run this test, you're gonna remove the EVAP vent solenoid from under your Express (Savana) van and blow air into its fresh air outlet port (check the photo above for reference).

If everything's good with the vent solenoid, the air will go through the outlet port and pass smoothly to the other side of the solenoid (the air filter canister side).

You can either use compressed air or just blow into the EVAP vent solenoid with your mouth.

OK, let's get testing:

1. 1

   Disconnect the EVAP vent solenoid from its connector.

2. 2

   Remove the EVAP vent solenoid from its place.
   
   This is done by removing the bolt from the solenoid's mounting bracket.

3. 3

   Disconnect the plastic line that connects the EVAP vent solenoid to the EVAP carbon canister.
   
   This plastic line is the one that connects to the EVAP vent solenoid's fresh air outlet port.
   
   Your EVAP vent solenoid should look like the one in the photo above.

4. 4

   Blow air into the vent solenoid's fresh air outlet port.
   
   I usually clean the fresh air outlet port and use my mouth for this step.

5. 5

   Air should easily pass thru' the EVAP vent solenoid.

Let's take a look at what your test results mean:

CASE 1: Air passed thru' the EVAP vent solenoid. This is the correct and expected test result.

The next step is to bench-test the EVAP vent solenoid. For this test go to: TEST 3: Bench Testing The EVAP Vent Solenoid.

CASE 2: Air DID NOT pass thru' the EVAP vent solenoid. This result tells you that the vent solenoid is either obstructed (internally) or is bad and is stuck in its closed state.

Although some folks recommend cleaning the EVAP vent solenoid by blowing compressed air into its fresh air outlet until all the dust is blown out of it and you can easily blow air through it with your mouth, I've found that this procedure only works if the solenoid itself is OK (as in not stuck in its closed position).

If the EVAP vent solenoid's filtering element is dirty and clogged with dust (and the solenoid is NOT stuck closed), cleaning it will help allow fresh air to pass thru the solenoid.

In my experience, even if the solenoid can be unclogged with compressed air, it tends to clog up more quickly than a new unit. Therefore, my recommendation is to simply replace the EVAP vent solenoid for a more lasting fix.

TEST 3: Bench Testing The EVAP Vent Solenoid

Now that you've confirmed the EVAP vent solenoid has power (10 to 12 Volts) and is allowing air to pass through it (meaning it's not stuck closed), it's time to bench-test it.

This is a simple process of connecting the EVAP vent solenoid to 12 Volts and Ground from your van's battery using jumper wires.

Once the solenoid receives power and Ground, it should close up, blocking the passage of air through it.

To avoid accidentally shorting the jumper wires together when applying battery voltage and Ground to the solenoid, I recommend using jumper wires with insulated alligator clips.

You can check out an example of these jumper wires with insulated alligator clips in photo 2 of 2 in the image viewer above.

OK, let's get started:

1. 1

   Connect the red insulated jumper wire to the male terminal labeled with the letter A in the photo above.

2. 2

   Connect the other end of the red jumper wire to the battery positive (+) terminal.

3. 3

   Connect the insulated black jumper wire to the male terminal labeled with the letter B.

4. 4

   Connect the other end of the black jumper wire to the battery negative (-) terminal.

5. 5

   The EVAP solenoid should make a 'click' sound as soon as you apply Ground to it.
   
   With 12 Volts and Ground applied to the EVAP vent solenoid, the solenoid should be closed and should not allow any air to pass thru' it.

6. 6

   Blow air into the air outlet port of the solenoid (you can use your mouth) to make sure that the solenoid has closed and is NOT allowing air to pass thru' it.

7. 7

   You should not be able to blow air across the EVAP vent solenoid.

Let's take a look at what your test results mean:

CASE 1: The vent solenoid activated and did not allow air to pass thru' it. This is the correct and expected test result.

You can conclude that the EVAP vent solenoid is good if you have:

• Confirmed that the EVAP solenoid is getting 10 to 12 Volts (TEST 1).
• Confirmed that you can easily blow air thru' the EVAP vent solenoid in its OFF state (TEST 2).
• Confirmed in this test section that the EVAP vent solenoid closes and blocks air going thru' it when you applied 12 Volts and Ground to it.

CASE 2: The vent solenoid activated but still allowed air to pass thru' it. This test result lets you know that the EVAP vent solenoid is bad and needs to be replaced.

CASE 3: The vent solenoid DID NOT activate and still allowed air to pass thru' it. This test result lets you know that the EVAP vent solenoid is bad and needs to be replaced.

More Chevy Express/GMC Savana Articles And Tutorials

You can find a complete list of articles and diagnostic tutorials for the V8 Chevy Express and GMC Savana here:

• GM 4.8L, 5.3L, 6.0L Index of Articles

Here's a sample of the tutorials you'll find in the index:

• How To Test For The Fuel Pump (2008-2013 V8 Chevy Express, GMC Savana).
• How To Test For A Blown Head Gasket (2003-2013 V8 Chevy Express, GMC Savana).
• How To Diagnose An Engine Cranks But Does Not Start Problem (2003-2007 V8 Chevy Express, GMC Savana).
• How Can I Tell If The Automatic Transmission Is Bad? (2003-2013 Chevrolet Express, GMC Savana).