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

The EVAP vent solenoid is a critical part of the EVAP system on your Express or Savana van. In this tutorial, I'll show you a super easy way to test it that doesn't require expensive diagnostic equipment (like a scan tool).

With your test results, you'll be able to easily find out if it's bad or not. Your test result will also help you find out if the EVAP vent solenoid itself is behind a trouble code P0446 or P0449.

APPLIES TO: This tutorial applies to the following vehicles:

• Chevrolet Express 1500, 2500, 3500: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013.
• GMC Savana 1500, 2500, 3500: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013.

Symptoms Of A Bad EVAP Vent Solenoid

Interestingly, despite its important role in emissions control, a malfunctioning EVAP vent solenoid typically doesn't directly cause engine performance issues or affect the drivability of the vehicle.

Generally you'll only see one or more of the following symptoms:

1. The check engine light will be illuminated by one of the following trouble codes:
   • P0446: Evaporative Control System Vent Valve Performance.
   • P0449: EVAP Canister Vent Solenoid Control Circuit Problem.
2. Pressure in the gas tank when you remove the gas tank cap.
3. Your Express (Savana) van fails the emissions test.
4. Difficulty filling up the gas tank with fuel.

What Does The EVAP Canister Vent Solenoid Do?

The EVAP canister vent solenoid, at its core, is just a simple ON/OFF valve. In its OFF state, it allows fresh air into the EVAP system. In it's ON state, it blocks the flow of fresh air into the EVAP system.

Here's how it works in more detail:

• ON - Closed Position (Sealing the System): In this state, the vapors in the canister are prevented from escaping into the atmosphere. It also creates a sealed system that allows the EVAP system to be tested for leaks.
• OFF - Open Position (Venting the System): In this state, outside air is allowed to enter the charcoal canister, which helps in purging the fuel vapors stored in it. The purged vapors are then drawn into the engine intake, where they are burned along with the fuel injected into the cylinders, reducing harmful emissions.

If the EVAP vent solenoid fails, it'll either stay stuck in its open or closed position, which cause the PCM to trigger the check engine light and an EVAP canister vent solenoid diagnostic trouble code.

Where To Buy The EVAP Vent Solenoid

The AC-Delco brand is the original equipment (O.E.) part for your Chevrolet Silverado (GMC Sierra). Dorman is another trusted brand.

The following links will help you comparison shop for the EVAP vent solenoid:

What Tools Do I Need?

To test the EVAP vent solenoid, you'll need:

• A multimeter.
• Two jumper wires with insulated alligator clips.

The insulated alligator clips will help you avoid shorting the jumper wires together when connecting them to the male spade terminal of the EVAP vent solenoid when bench-testing it.

You'll need hand tools to remove the EVAP vent solenoid from its place underneath your Chevrolet Silverado (GMC Sierra).

TEST 1: Making Sure That The EVAP Vent Solenoid Is Getting Power

The EVAP vent solenoid gets its power, 12 Volts DC, from the CAN VENT SOL fuse found in the underhood fuse box of your Chevy Express (GMC Savana).

The wire (of the solenoid's 2-wire connector) that carries this voltage to the solenoid is gonna be one of two colors: orange (ORG) or red with white stripe (RED/WHT).

For our first test, we gonna check if the vent solenoid is indeed getting 10 to 12 Volts from that ORG (or RED/WHT) wire.

In the illustration of the connector above, the ORG (or RED/WHT) wire connects to the female terminal marked with the letter A.

OK, let's start:

1. 1

   Disconnect the EVAP vent solenoid from its connector.

2. 2

   Place your multimeter in Volts DC mode.

3. 3

   Connect the black multimeter test lead to a good Ground point on the frame.
   
   NOTE: It's important that you Ground the black multimeter test lead to a clean and uncorroded spot on your van's frame to get a correct test result. What I personally do is use a battery jump start cable to connect the black multimeter test lead to the battery negative (-) terminal to ensure a good connection to Ground.

4. 4

   With the red multimeter test lead, gently probe the terminal labeled with the letter A.
   
   Terminal A is the one that connects to the ORG or RED/WHT wire of the 2-wire EVAP vent solenoid connector.

5. 5

   The multimeter should register 10 to 12 Volts.
   
   NOTE: Power should be present at all times - no need to turn the key to the ON position.

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

CASE 1: 10 to 12 Volts DC are present. This is the correct and expected test result.

The next step is to go to: TEST 2: Making Sure The EVAP Solenoid Is Allowing Fresh Air Intake.

CASE 2: The indicated voltage is not present. Without power, the EVAP vent solenoid will not function.

This is usually caused by one of two things:

• The CAN VENT SOL (10A) fuse is blown in the underhood fuse box.
• There's an open-circuit problem in the wiring between the EVAP vent solenoid's connector and the underhood fuse box.

Your next step is to check the fuse and retest for the presence of 10 to 12 Volts in terminal B.