So i've been trying to figure out why none of the grounds to my solenoid rack work. If i check for continuity between the BW (ground) wire of any of the plugs and the batt. i get nothing. At first I thought that I might have a broken wire some where in the loom. Testing it proved that the wires connect all the way to the ecu. Also shows cont. between the pressure sensor ground (its the same BW wire). So with the car off there is no ground from the ecu. With the car on the pressure sensor gets ground but still not the solenoids. this is the weird part. With the car off I check cont. between the BW (ground) wire on the pressure sensor to a solenoid ground. I get continuity between the wires. If i turn the car on, the continuity between the same wires shows no cont. WTF?

Any Ideas. Right now i am leaning twords just running all of the solenoids to the chassis and see if that gets them working right.

 

The Black/White wire is the voltage wire that comes from the Main relay. The second wire, which leads to the ECU from the solenoid, will either have voltage or a ground. When it has a ground as determined by the ECU then the solenoid is activated. When both wires have voltage then the solenoid is not activated but in a dormant state.

 

What do you know. 3I = B/W = main relay. But now I'm really confused. I put a new wire into the b/w on my Fuel Press Reg. If I connect that wire to ground, the solenoid goes "click" and my fuel pressure goes up. Guess I gotta dest the Blue orange wire now.

Crap

Thanks satch.
Aug

 

Oh and who is the idiot that used black for a 12v source?!?!?!
Yes its got a white tracer but come on!!!!!

 

Just wondering if the Rack is attached to the manifold?
Usually the Rat's nest has a couple 10mm bolts near the rear passenger side of the engine.(on a s4 N/a anyways..a real pain).
If the rack is laying loose then it wouldn't get or BE a ground.

 

When the engine is running the Blue/Orange wire has voltage on it. If you supply a ground to the other wire it would make sense that the solenoid would click "if" the solenoid doesn't care which wire supplies the ground and which supplies the voltage.

EDIT: When the valve is on no vacuum is supplied to the FPR and this causes the fuel pressure to increase from about 30 to about 40. Pulling the vacuum hose off of the FPR does the same thing.

 

the main relay supplies power to all the solenoids, and injectors and stuff, and the ECU switches the ground. no comment on the black wire thing, but its rare an automotive circuit doesn't have the ground side switched

foxed.ca has the wiring diagram, if you don't already

 

The solenoids are housed in plastic thus it can't possibly receive a ground or non ground from the mounting rack. The ground for the emission solenoids comes from the ECU and only the ECU.

 

Thanks Satch,I learned something new!