What did I disconnect?

[amr0510]

New here and this is my first post as well as my first 964. It's a 1990 C4 Coupe with 68k miles and I absolutely love it. Have been wanting one for years and finally pulled the trigger. Being eager to start updating it, I started with the interior. The previous owner had a digital race monitor and a bunch of messy wiring behind the gauges. I cleaned it up and removed the DRM. He also had the fog light relay sitting behind the dash and being used as a bridge back to the DME port in the fuse box. I cleaned all that up and plugged the Hello fog light relay to the correct port. I purchase a new DME relay (German made) and plugged it in 41 where it belongs. The car cranks but does not start. I ran the 3 prong jumper and it starts and runs perfectly as it did when it arrived but the fuel pump continues to run of course.

I tested the coil pins in the fuse box for port 41 and I'm not getting either ignition or ground. I'm wondering if somehow the fuse box should be getting power and/or ground from something behind the dash in a daisy chain.

Any help would be greatly appreciate. I'm at a loss. Thanks.

[teeitup]

You may also want to post this on the Rennlist 964 Forum.

[amr0510]

Originally Posted by teeitup

You may also want to post this on the Rennlist 964 Forum.

I did!

[bazar01]

DME relay has two 12V outputs.
1 - fuel pump power
2 - injectors, DME term 37, 2 ignition control units and 2 ignition coils, O2 sensor, etc.

Since it fires up with the jumper, then you are missing the control voltage to the DME relay at terminals 85 and 86.
This 12V signal at 85 and 86 is present when DME control unit is powered up at terminal 18 (permanent 12V) and terminal 37 when DME relay is energized while starting and rpm is seen by flywheel sensor.