Installing HFS-5 in 1998 VW Jetta. ECU switches ground?

[tsa1982]

Hello,

I have continuously had a problem with my HFS-5 install. The install was performed by a qualified shop in Connecticut USA, Sleepers Performance.

The correction of this install has been left for me to figure out though...

From my research it appears my car has a NEGATIVE switching ECU. The Aquamist DDS3 is wired to the ground side of the #1 fuel injector at the ECU. The positive side of the fuel injector lead on the DDS3 is wired to the positive circuit that runs the injectors, but this was done at the fuse box because it was the least intrusive way to connect to the positive lead without splicing another wire at the ECU plug. This is possible because the + circuit that runs the injectors is the same circuit that runs the fuel pump relay. It is a constant power source if the ignition is switched on.

The HFS-5 system is injecting mixture when the car is set to accessory and engine not running. This is a problem.

What is the wiring configuration needed in order to control the DDS3 with a ground switching ECU?

Thank you for being here to help!

Ted Anderson
CT USA