How To Test The Digital EGR Valve (1990-1994 3.1L V6 Chevrolet And Pontiac Vehicles)

TEST 2: Testing The Resistance Of The Solenoids

This test section will focus on testing the resistance of the three solenoids (within the EGR valve).

With this resistance test, we want to determine if any of the solenoids have suffered an internal open-circuit or short-circuit problem.

If the solenoid has an internal short-circuit problem, you'll get a resistance reading of 0 to 5 Ohms.

If the solenoid has an open-circuit problem, you'll see a resistance reading in the thousands of Ohms (K Ohms), or your multimeter will report the letters OL.

NOTE: This test is performed on the male spade terminals of the EGR valve itself.

IMPORTANT: The EGR valve must be at ambient temperature before removing and testing it. If the engine has been running for any length of time, the EGR valve will be hot! Let the engine cool down completely before removing and testing the EGR valve.

OK, these are the test steps:

1. 1

   Remove the EGR valve from the intake manifold.

2. 2

   Set your multimeter to Ohms mode.

3. 3

   Connect the red multimeter test lead to male terminal D.

4. 4

   Probe terminal A with the black multimeter test lead. Terminal A belongs to solenoid A.

5. 5

   You should see a resistance value around 12 Ohms.
   
   If the solenoid has a short-circuit problem, you'll see a value around 0 Ohms on your multimeter.
   
   If the solenoid has an open-circuit problem, you'll see a value in the thousands of Ohms (K Ohms) or the letters OL (digital multimeter).
   
   NOTE: The EGR valve must be at ambient temperature to test the resistance of the solenoids.

6. 6

   Repeat steps 4 to 5 on terminals B and C.

Let's see what your test results mean:

CASE 1: The resistance of each solenoid is within the indicated value. So far so good since this is the correct test result.

Your next step is actuate each solenoid and see if they open/close their ports. Go to: TEST 3: EGR Solenoid A Performance Test.

CASE 2: The multimeter reported a short-circuit problem in one of the solenoids. This test result tells you that the solenoid is bad. Replace the EGR valve.

CASE 3: The multimeter reported and open-circuit problem in one of the solenoids. This test result tells you that the solenoid is bad. Replace the EGR valve.

TEST 3: EGR Solenoid A Performance Test

Each solenoid is tasked with opening/closing a port on the underside of the EGR valve. When the port opens, exhaust gas enters and passes thru the EGR valve and into the intake manifold (photo 2 of 3 points to these ports).

It's not uncommon for a solenoid to fail and become unable to open its port when commanded ON by the fuel injection computer.

In this test section, we'll apply power and Ground from a 9 Volt alkaline battery (like the one you find in a smoke detector) to solenoid A (we'll test the others in the following TEST sections).

With power and Ground applied to EGR solenoid A, the port labeled with the letter A (see photo 2 of 3) should open.

NOTE: We won't use the vehicle battery (for power or Ground) to actuate any of the EGR valve solenoids for test safety reasons. The 9 Volt alkaline battery I'm referring to is the one that's used in smoke detectors and other small portable appliances (see photo 3 of 3 in the image viewer above).

IMPORTANT: To accomplish this test without complications or a 'false-positive' test result, you'll need jumper wires with insulated alligator clips. You can buy these at your local auto parts store or purchase them online here: Jumper Wires With Insulated Alligator Clips (at: amazon.com).

Alright, these are the test steps:

1. 1

   Connect one end of the red jumper wire to the positive (+) terminal of the 9 Volt battery.
   
   NOTE: This test is done with the EGR removed from the engine.

2. 2

   Connect the other end of the red jumper wire to terminal D (see the illustration above).

3. 3

   Connect one end of the black jumper wire to terminal A.

4. 4

   Connect the other end of the black jumper wire to the negative (-) terminal of the 9 Volt battery.

5. 5

   You should hear an audible click and the port labeled with the letter A should open.

6. 6

   Disconnect the 9 Volt battery from the black jumper wire.

7. 7

   The EGR valve port A should close.

8. 8

   Repeat steps 4 thru 7 several times to make sure of your test results.

Let's take a look at what your test result means:

CASE 1: The solenoid 'clicked' and opened port A. This is the correct test result and confirms solenoid A is functioning correctly.

Your next step is to test solenoid B. Go to: TEST 4: EGR Solenoid B Performance Test.

CASE 2: The solenoid DID NOT 'click' and DID NOT open port A. This test result confirms that solenoid A is bad. Replace the EGR valve.

CASE 3: The solenoid 'clicked' but DID NOT open port A. This test result confirms that solenoid A is bad. Replace the EGR valve.