March 5, 200719 yr Can anyone tell me why the EGR switch drops in and out while engine is running? History; My check engine light came on and the code was EGR Flow. I used a vacuum pump to check the valve and it was working normally. I checked the vacuum from the manifold and it moved with the speed of the engine, as normal. I then checked the vacuum between the switch and the valve and found it going on and off. It does it wether the engine is at lower RPM or reved to 3000 RPM and held. I have the switch bypassed right now so the EGR will operate directly off manifold vacuum and have not gotten the light back yet, although I am expecting it so I can recheck the code. Anyone come across this before?
March 5, 200719 yr Did you check to see if the power and/or the ground was going on/off at the same time ? More than likely it's the valve that is defective . SEA#3
March 6, 200719 yr Author Did you check to see if the power and/or the ground was going on/off at the same time ?More than likely it's the valve that is defective . SEA#3 No, since the wiring goes around and under engine components I could not follow it. I was wondering if anyone knows if the computer operates the switch open and closed or if there is a problem. I checked the valve with a hand vacuum pump and it worked fine, also hooked it directly to the manifold vacuum and it opens when the car is running. If the switch is supposed to operate intermitently, it means there is a blockage between the crankcase and the valve (I did not disconnect the tubing).
March 7, 200719 yr The ECM does operate the VSV (Vacuum Switching Valve) and it is usually on when the throttle is just off idle. you need to check if you are getting an intermittent power and/or ground signal or if its the VSV that is intermittent The Yellow/red wire should have power and the Green/black wire should be ground signal from the ECM SEA#3
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