Hi all - I've successfully been running Option B mod for several months, but recently got a Shuttle Valve Switch Electrical Failure code that won't go away. I pulled the SVS and checked the wiring, and removed and re-crimped all connectors. Since Option B changes the wiring, I'm having trouble understanding how to apply the diagnostics here to the Option B setup.

I did notice that there was no electrical continuity between the positive and negative sides of the SVS leads. Does this indicate a dead SVS that I just need to replace with a new one? The current SVS is a cheap $25 no-name brand.

 

The 8 valve solenoids inside the modulator have the continuity resistance to chassis as sketched here; remove the plug and probe the terminals to confirm :

Post #2 at ----> https://landroverforums.com/forum/di...-sound-119576/
If you feed 12V to each solenoid terminal, should hear them click.

 

You're saying that valve solenoids can cause Shuttle Valve Switch Electrical Failures? Strange...I'll give it a shot.

 

Am not saying other than the solenoids resistance continuity are readable at the terminals shown, and I do not see any "positive side" anywhere. There is only loads to the Wabco compfuser to be read/probed at pins 1, 2, 4, 5, 10, 11, 12, 13. and the resistance at pin 9 changes if pedal is pushed.

Compfusersends+to------------------------------>solenoid--------------------------------------chassis pin8.

 

I don’t understand anything you just said, or how it would address the problem.

 

Verify you have a good ground. Most important step when performing the update/bypass.

 

Damn! Seems like it was the ground connection, loose screw on the AC line holder. Not sure how I missed that, thank you!

edit: jk still have problems

 

Well it got weirder…no codes and no lights, but ABS and Hill Descent do not work.

 

I replaced my SVS with a fresh one, did Option B to that one, and still get Shuttle Valve Switch Electrical Failure. My ground is good, so I have no idea how this is possible at this point.

 

How did you erase ABS error codes ?