Do you want to test the purge valve with a multimeter?  Great you are in the right place. After reading so many articles on the internet, I was not satisfied so I have decided to write in detail on how you can check your valve.

There are different steps involved in testing the vapor canister purge valve. But before that first of all, we will discuss 

What is a Multimeter?

A multimeter is a tool for measuring electrical quantities like resistance, voltage, and current. All these meters (ohmmeter, voltmeter, and ammeter) that measures those quantities are combined to a single meter is known as multimeters. There are two types of multimeters:

1. Analog Multimeters

Analog multimeters work on the principle of moving coil meters. These meters use the deflection of an indicator needle to indicate the level of the measurement on an analog display.

2. Digital Multimeters

What is a Purge control valve?

purge valve

Canister Purge valve solenoid valve is an important component in a car utilizing a combustion engine. The Purge solenoid takes vapors from the fuel tank through an input hose. When the purge valve is operating correctly, it uses a 12 V supply from the car’s control computer. There are two main modes of operation for the Purge valve.

  • OPEN
  • CLOSED

The fuel vapors after that undergo the purge valve as well as move right into the outlet hoseFrom here they undergo the consumption and also right into the engine to be combusted.

what is RX1 on a multimeter?

Purge control valve Faults

There are two main faults of the Purge or solenoid valve.

  • Stuck Open Purge Valve

A stuck open purge valve can cause rough idling of the engine and engine misfiring. Also, because of this issue, you may face difficulty in card starting. The stuck open purge valve creates an air vacuum leak in the intake hose. This creates a sucking of extra air from the fuel tank. The sucked air is more than is required and disturbs the engine’s operations. The worst thing about a stuck open purge valve is that you can go for weeks without noticing until the purge valve is completely damaged.

  • Stuck Closed Purge Valve

Because of the stuck closed purge valve, an alert light will be activated immediately, letting you know there is a problem. So if the engine starts rough idling, or you are having a tough time starting the car especially during winter. Then it is recommended to test the valve with a multimeter.

Tools Required to test Purge valve with a multimeter

Two tools are required for testing of circuit breaker with a multimeter

  1. Digital multimeter
  2. Air Pump
  3. Purge Valve
  4. Battery (12V)
  5. 5/8 inch rubber hose with clamps

The question arises why we need a digital multimeter why we can’t use an analog meter. As a Digital multimeter is easy to use and due to digital display chances of reading error are less. You can use any DMM to measure current, voltage, etc. But keep in mind you should know how to use a multimeter before testing.

How To Test Purge Valve With Multimeter

There are four steps involved in the testing of purge multimeter

     1.  Continuity Test (using Multimeter)

how to test purge valve with multimeter

To perform the continuity test follow these steps

  • Disconnect the purge valve from the engine.
  • Please ensure the car has been idle for at least 30 minutes.
  • If you are not comfortable doing this please contact a mechanic
  • Set the multimeter to continuity mode.
  • Connect two probes, to check the meter is working properly.
  • Connect the probes to the power terminals of the purge valve. If you hear an audible sound, then the purge valve is working.
  • The reason for this is that most purge valves are solenoid purge valves and the purge valve’s casing from the positive and negative power terminals.
  • If the beep is not audible, means the purge valve is damaged and must be replaced.

     2. Ohm meter readings (Using DMM)

how to test purge valve with multimeter

For taking the ohmmeter reading follow these steps

  • Move the multimeter dial to ohm.
  • Place the probes on the power terminals of the purge valve.
  • Taking the reading if it is a range of 14 to 30 ohms means that the purge valve is healthy.
  • If the readings are below and above the range, then valves need to replace.

How to Test a Circuit Breaker with a Multimeter

     3. Mechanical Click Test

To perform the mechanical click test follow these steps.

  • Take probes and connect them to your 12V battery terminal.
  • Connect the other ends of the probes to the terminals of the purge valve.
  • If you hear a click, then your purge valve is operating correctly.

   4. Close Test (using Battery)

To perform the mechanical click test follow these steps.

  • This test will show whether the purge valve is causing a vacuum leak or not.
  • Connect the 5/8 inch hose to the end of the purge valve that goes to the intake manifold of the engine. Make sure to tie the clamps.
  • Connect the other side of the hose to the handheld vacuum pump.
  • Pump the handheld vacuum pump to about 20 or 30 in-Hg/mm-Hg.
  • Leave it there for about 2 to 3 minutes.
  • Vacuum pumps should not be leaking air. If this happens, it means that there is an air leak between the purge valve or the connection between the hose and purge valve is not solid.
  • Make sure the hose is fastened correctly.
  • Run the test again.
  • If it still leaks then the purge valve is damaged.
  • If after 2 or 3 minutes the vacuum pump’s value is the same, then take the probes and connect them to the 12V battery supply.
  • Connect the other side of the probes to the terminals of the purge valve.
  • If you hear a click and the vacuum pump quickly goes to 0. It means the purge valve is working correctly.

After reading this article “How to test a purge valve” you will be able to check the valve. We have tried to cover each aspect of the purge valve and will look for more and try to add those in the next update. Have you found anything helpful? Let us know in the comments section below.

 

By inham

Inhamullah Jadoon is an Electrical Engineer and Founder of geekyengineers.com. He has huge experience in the field of Engineering and assisting Engineers in Software and Hardware issues.

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