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

TEST 4: EGR Solenoid B Performance Test

You'll test solenoid B in the same manner as solenoid A, the difference being that you'll Ground a different terminal (to activate solenoid B).

Specifically, you'll connect terminal D to power and terminal B to Ground. These connections are made to the same 9 Volt battery you used in TEST 1.

Connecting solenoid B terminals B and D to the 9 Volt battery should open the port labeled with the letter B in photo 2 of 2.

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, let's get testing:

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 B.

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 B should open.

6. 6

   Disconnect the 9 Volt battery from the black jumper wire.

7. 7

   The EGR valve port B 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 B. This is the correct test result and confirms solenoid B is functioning correctly.

Let's move on to the next and last test section and test solenoid C: TEST 5: EGR Solenoid C Performance Test.

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

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

TEST 5: EGR Solenoid C Performance Test

For your final test, you'll check that solenoid C is opening/closing the port labeled with the letter C.

You'll connect terminal D to power and Ground terminal C to your 9 Volt alkaline battery.

If solenoid C functions correctly, you should see port C open/close as you activate/deactivate it.

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, let's get testing:

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 C.

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 C should open.

6. 6

   Disconnect the 9 Volt battery from the black jumper wire.

7. 7

   The EGR valve port C 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 C. This is the correct test result and confirms solenoid C is functioning correctly.

If all three solenoids tested OK (and all three ports opened/closed), you can conclude the EGR valve itself is functioning correctly and isn't behind the EGR diagnostic trouble code.

The most likely cause of the EGR valve trouble code (illuminating the check engine light) is one of the following:

• Carbon buildup blocking the EGR port in the intake manifold.
• Carbon buildup blocking the EGR passage in the EGR adapter to exhaust manifold pipe.

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

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

More 3.1L Chevrolet And Pontiac Diagnostic Tutorials

You can find a complete list of 3.1L Chevrolet and Pontiac tutorials in this index:

• GM 3.1L Index Of Articles.

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

• How To Test The Fuel Pump (1990-1994 3.1L V6 Chevrolet And Pontiac Vehicles).
• How To Test The TPS (1990-1994 3.1L V6 Chevrolet And Pontiac Vehicles).
• How To Test The Alternator (1990-1994 3.1L V6 Chevrolet And Pontiac Vehicles).
• How To Test The Engine Compression (3.1L V6 Chevrolet And Pontiac Vehicles).