Has anyone done this on a B5 A4? I've done it on my Z, and all it requires is some wire, some connectors, a switch and a good hiding spot; you simply wire it in before the fuel pump relay, making the closed circuit to the fuel pump open whenever you flick the switch. It's a very good theft deterrent because your average thief will not be expecting a fuel cut-off switch or even know where to find it if you hide it well, and it is also useful when you want to relieve fuel pressure in the fuel lines: instead of having to get to the relay and unplug it, you can simply flick the switch.

Before I go digging around, does anyone know physically where the fuel pump relay is? And has anyone done this on their B5? I assume the wiring to the fuel pump is pretty straight forward, anyone know otherwise?

 

yeah its a great idea and hide the switch in a really cool spot like one of the useless buttons on the radio or around the radio it would be cool

 

Bumpity bump.

 

I did the exact same thing on my Z (1990 converted 2+2TT) - hid it in the feed vent on the side of the dash where it fed air to the door vent. I tapped into the fuel pump relay ground wire though. I haven't done it on the A4 yet but I plan to. I sure as hell won't put the switch on the dash though - like turtleboy said, hide it or what's tge point? Definitely a worthwhile thing to do though.

 

Do you happen to know if our A4 wiring system is similar (been too busy to take a look myself lately). I know it "should" be, but on a lot of cars the manufacturers like to wire in a lot of "unnecessary" components. Or where the fuel pump relay is located.

@ImTheDevil, Out of curiosity, are you on 3ZC.com or twinturbo.net?

 

It should be tge same - after all, a relay works the same way regardless of the car and the fuel pump relay should trigger from the ignition switch to prime the system. I'll look more into it in the upcoming little while here and will post up what I find and do. There are likely more components on the Audi that could be disabled by security switches since these cars are newer and under the control of more electronics. Still, I'd rather shut the pump down than anything else - with OBD2 it seems likely that killing the coils or other parts would be a lot more likely to trip a CEL. And my 300 is long gone - sold it a few years back since with two toddlers at the time (they're school-age now), a Z was pointless. I used to scroll through the tech section of TT.net on occasion but I haven't gone there for several years now. There are times that I miss the car but I guess I've just changed focus since my Z at 50mph in 5th gear could've wasted my Audi at the same speed in 3rd gear and 99% of the time it doesn't even bother me. I certainly wouldn't be against another one at some point in the future but I think if I was going to angle for another Japanese sports coupe I'd probably hand the money to someone selling an NSX (I've had an NSX-shaped hole in my garage since they came out...and still do ).