Ford EGR Valve Vacuum Solenoid Circuit Descriptions
The EGR Vacuum Regulator Solenoid is the second electrical component of the EGR system of your Ford (or Mercury or Lincoln) car or truck that you'll be diagnosing with the help of this article.
The EGR Vacuum Regulator Solenoid is the same no matter what type of DPFE sensor your Ford vehicle is using.
- Circuit labeled 1:
- Power (12 Volts) Circuit.
- Circuit labeled 2:
- Solenoid Control Signal from PCM (Powertrain Control Module=Fuel Injection Computer).
The color of the wires on your Ford vehicle will not match the ones in the photos in the image viewer, this is no cause for concern. The circuit descriptions are the same no matter what the individual color of the wires on your Ford (Lincoln, Mercury) car or truck.
Safety Precautions When Testing
Most of the tests that you're about to do are done with your vehicle's engine running (idling). Therefore, it's important that you stay alert, use common sense and take all necessary safety precautions to keep yourself safe.
Also, the EGR valve can get very hot and so you must take care not to burn your hands or fingers.
TEST 1: EGR Valve Vacuum Pump Test
IMPORTANT: To success-fully use this info and correctly diagnose the EGR valve system on your Ford (or Lincoln or Mercury) car or truck do not skip from test to test on your own. Follow the indicated flow of test steps that each test recommends.
The very first thing that we'll do is to verify that the EGR valve itself is working. You'll need a vacuum pump for this test.
This test is done with the engine running, so take all safety precautions.
- Remove the vacuum hose from the EGR valve.
- Connect a vacuum pump, using a vacuum hose, to the EGR vacuum hose nipple on the EGR valve (see photos in image viewer).
- Have an assistant crank up the car (or truck).
- Once the engine has started and is idling, apply vacuum with the vacuum pump.
- As you apply vacuum, the engine should start to immediately idle very rough and possibly stall.
- Now, apply vacuum again with the vacuum pump and hold the vacuum for about a 20 second count.
- The vacuum pump gauge's needle should stay steady at whatever number of in.Hg (or kpa) vacuum you have pumped it up to.
- If the vacuum pump gauge's needle does not hold steady, but starts to go down to 0 (zero) in.HG, check that the vacuum hose that is connecting the vacuum pump to the EGR valve is making a tight connection on both the EGR valve and the vacuum pump.
- When you are sure of your result, turn off the engine.
Let's find out what your test results mean:
CASE 1: If the engine idle grew worse as you applied vacuum with the vacuum pump and the vacuum pump's gauge needle stayed steady, then this result indicates that the EGR valve is working correctly and that the EGR passages in the intake manifold (and in the EGR valve itself) are not blocked with carbon. The next step is to verify that the DPFE sensor is working correctly. Leave the vacuum pump connected to the EGR valve and go to: TEST 2: Testing The DPFE EGR Flow Signal.
CASE 2: If the engine idle grew worse as you applied vacuum with the vacuum pump and the vacuum pump's gauge needle DID NOT stay steady: Verify that the vacuum hose you have connected to both the vacuum pump and the EGR valve is not leaking vacuum and re-do the test.
If after verifying that the vacuum hose is making a tight seal and the vacuum needle on the gauge still drops (after applying vacuum to EGR valve with the engine idling), then this result indicates that the EGR valve's inner rubber diaphragm is torn and leaking vacuum, although the EGR valve is working correctly. Replace the EGR valve and road-test the car or truck.
CASE 3: If the engine idle DID NOT CHANGE as you applied vacuum with the vacuum pump, this indicates one of two things either that 1) the EGR valve is BAD because its rubber diaphragm is torn, or 2) that the EGR exhaust gas passages are blocked in the EGR valve itself, or 3) the inlet EGR orifice on the intake manifold is blocked with carbon. The next step is to remove the EGR valve and bench test it, go to: TEST 3: Bench Testing The EGR Valve.