This tutorial will help you to test the EGR vacuum solenoid on the 1994-1995 2.2L Chevrolet S10 (GMC Sonoma).
I think you'll be surprised at how easy it is to determine if the EGR vacuum solenoid is good or bad.
I've also included the links where you can save a few bucks on its purchase.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Solenoide De Vacío De La Válvula EGR (1994-1995 2.2L Chevrolet S10, GMC Sonoma) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 2.2L Chevrolet S10: 1994, 1995.
- 2.2L GMC Sonoma: 1994, 1995.
EGR VALVE TEST: You can find the EGR valve test here:
Symptoms Of A Bad EGR Vacuum Solenoid
Depending on the nature of the EGR vacuum solenoid fault, you may or may not notice an engine performance problem.
Generally, you'll see the EGR vacuum solenoid fail in one of two ways:
- The EGR vacuum solenoid stops working. In this scenario, it does not supply vacuum to the EGR valve when the computer commands it ON.
- The EGR vacuum solenoid becomes stuck in its open position. In this scenario, it allows vacuum to the EGR valve at all times.
If the EGR vacuum solenoid is stuck open, the engine will suffer a rough idle condition.
This is the OBD I EGR system diagnostic trouble code you'll see when an EGR system fault occurs:
- Code 32: EGR System Problem.
How The EGR Vacuum Solenoid Works
The EGR vacuum solenoid acts as a simple ON/OFF switch that allows/cuts off vacuum to the EGR valve.
In a nutshell, this is how the EGR vacuum solenoid works:
- The EGR vacuum solenoid receives 12 Volts DC as soon as the engine is started but remains OFF (does not allow vacuum to pass thru it).
- Once the engine has reached its normal operating temperature and it's under load, the fuel injection computer commands the EGR vacuum solenoid ON.
- The fuel injection computer commands the EGR vacuum solenoid ON by internally grounding it.
- In its ON state, the vacuum solenoid will allow vacuum entering its inlet port to pass to its outlet port. Since the outlet port is connected to the EGR valve, vacuum now reaches the EGR valve.
It's important to note that the EGR vacuum solenoid is normally closed. In other words, it does not allow vacuum to pass from its inlet port to its outlet port (until commanded ON).
Where To Buy The EGR Vacuum Solenoid And Save
The EGR vacuum solenoid on the 1994-1995 2.2L Chevrolet S10 (GMC Sonoma) isn't an expensive emissions control component. The following links will help you to comparison shop for the EGR vacuum solenoid of known Automotive brands (avoid knock off parts).
TEST 1: Is The EGR Vacuum Solenoid Stuck Open?
To get your EGR vacuum solenoid diagnostic underway, I'll ask you to check if the solenoid is receiving vacuum with the engine idling.
As I mentioned before, the EGR vacuum solenoid should not provide vacuum to the EGR valve when the engine is idling.
If your test result confirms that vacuum is present at the EGR valve's vacuum line, you can conclude that the EGR vacuum solenoid is stuck open.
You can also conclude that the EGR vacuum solenoid is behind the EGR system diagnostic trouble code that's lighting up the check engine light.
NOTE: You'll need a vacuum hose to attach to the EGR vacuum solenoid's inlet port.
These are the test steps:
- 1
Disconnect the EGR vacuum solenoid from its electrical connector .
- 2
Remove the EGR vacuum solenoid from its place on the intake manifold.
- 3
Connect a vacuum hose to its inlet port .
- 4
Blow air through the vacuum hose. You can use your mouth to blow air into the vacuum hose.
- 5
Air should not pass to the outlet port .
NOTE: Air may pass thru the solenoid (its vented to atmosphere), but it should NOT come out of its outlet port.
Let's take a look at what your test results mean:
CASE 1: Air DID NOT pass through to the outlet port. This is the correct and expected test result.
The next test is to apply power and Ground directly to the EGR vacuum solenoid. For this test go to: TEST 2: Applying 12 Volts And Ground To The EGR Vacuum Solenoid.
CASE 2: Air passed through to the outlet port. This test result confirms that the EGR vacuum solenoid is bad.
Replace the EGR vacuum solenoid.
