How to Measure Resistance in a Purge Valve

The purge valve in your vehicle is a normally closed solenoid valve that is opened momentarily when the engine is started to allow fuel vapors in the fuel tank to be drawn into the intake manifold and burned during combustion. Testing this valve's electrical component is straightforward using standard electronic test equipment. The average home mechanic can complete this test in just a few minutes.

Things You'll Need

• Digital volt/ohm meter
• Service manual

Instructions

1. Locate the purge valve using your service manual. Typically the purge valve is found near the evaporative emissions system (charcoal canister) near the rear of the car.

2. Unplug the electrical connector on the end of the purge valve. Most vehicles use a small blue or red lock on the connector to prevent it from loosening. Pull out on the locking tab and then press the latch on the connector to remove it from the valve. A resistance test cannot be performed on a component connected to the vehicle's electrical system.

3. Set the digital volt/ohm meter to measure ohms (a measure of resistance). Test the solenoid's coil by touching the tips of the red and black meter leads to the terminal pins inside the electrical connector cavity on the purge valve. Replace the valve if the measured resistance is "0" ohms (indicating a shorted coil) or "Infinite" ohms (indicating an open circuit coil).

Tips & Warnings

• Do not use an analog meter for this repair. An analog meter causes high current flow and may damage the on-board computer.