Wiring to the Porsche Shut Off Valve - part no. 996.605.201.01

[evetselous]

My 2000 Boxster (2.7 liter, Tiptronic) has developed the howling, moaning sound at the air intake under the fuel filler door that has troubled other owners. The noise comes on at idle and disappears once the throttle is opened.

I blew out the lines (none were obstructed) and replaced the Carbon Control Valve 996.605.213.01, the Fuel Vent Valve 996.201.143.01 and the Shut off Valve 996.605.201.01 without any change in the sound.

The sound comes from the Shut Off Valve, which is open at idle and, I think, should be closed. One terminal on the switch is connected to a wire that carries 12 volts when the car is at idle. The other terminal appears to have 3.5 volts, although the body of the switch has a molded icon indicating that it is to go to ground. I tested the Shut Off Valve that I removed. With the ground terminal connected to ground and the postive terminal connected to 12 volts, the valve snaps shut and stays shut.

I think that this switch is supposed to stay shut until the engine comes up to part throttle and that there is something wrong with the ground, but would like to know if anyone has a wiring diagram to let me know where the two wires to the terminal come from, if one of them is supposed to go to ground and if I am right about how and when the Shut Off Switch works.

[tony_986]

My 2000 Boxster (2.7 liter, Tiptronic) has developed the howling, moaning sound at the air intake under the fuel filler door that has troubled other owners. The noise comes on at idle and disappears once the throttle is opened.

I blew out the lines (none were obstructed) and replaced the Carbon Control Valve 996.605.213.01, the Fuel Vent Valve 996.201.143.01 and the Shut off Valve 996.605.201.01 without any change in the sound.

The sound comes from the Shut Off Valve, which is open at idle and, I think, should be closed. One terminal on the switch is connected to a wire that carries 12 volts when the car is at idle. The other terminal appears to have 3.5 volts, although the body of the switch has a molded icon indicating that it is to go to ground. I tested the Shut Off Valve that I removed. With the ground terminal connected to ground and the postive terminal connected to 12 volts, the valve snaps shut and stays shut.

I think that this switch is supposed to stay shut until the engine comes up to part throttle and that there is something wrong with the ground, but would like to know if anyone has a wiring diagram to let me know where the two wires to the terminal come from, if one of them is supposed to go to ground and if I am right about how and when the Shut Off Switch works.

I tried looking for a wiring diagram and no luck, one of my PDF files are corrupted.

I do not see a fuse or relay associated to that circuit, unless its associated with the fuel pump circuit.

Did you try running a ground jumper wire to it on the car?

Weird that a grounded terminal is reading 3.5 volts.

Sorry not much help

T

[evetselous]

Thanks for checking up on it. I will run a ground wire to the switch and see what happens. Funny how complicated the EVAP system is on the Porsche isn't it?

[evetselous]

I am getting codes P1124, P1126 and P0466, which I think are because the shut off valve is open at idle. Am I off base here? I don't want to rewire the switch if it is operating correctl.