ECU test connector added
 

I had a few burned resistors in my ECU and fixed them the other day. While I was in the area, I decided to do a few other mods. One was to add (2) 10ga ground wires to pins 3A, 3B, 3C and 3D according to the link below. FYI....before I did that I measured 0.2VDC on one of the ground leads at idle.
http://home.earthlink.net/~burntoast/3700.html

Next, I went to Radio shack and bought heatskrink, molex 12 pin and 9 pin female connectors, a roll of 20ga wire, spiral wire covering and flux cleaner. I cut 21 wires going to the ECU that I was interested to monitor with the car cold, at idle and under load according to the manual F1-79. I made up the molex connector in the house (about 1 hour) and labeled the end of each wire with the ECU pin number that I wanted to connect it to (so I wouldn't screw up when I got under the dash).

I spliced into each wire, cleaned it and then put heatshrink over it (about 3 hours). The entire bundle was then wrapped in aluminum foil tape because I noticed the old wires were covered in a copper foil. This was probably done to eliminate EMI interference into the ECU control signals. FYI.....DON'T RUN YOUR STEREO OR AMP WIRES BY THE ECU CONTROL WIRES! The plastic cover was installed back over the entire bundle and tie wrapped securely.

The bundle of 21 wires was covered with the plastic spiral covering and positioned so it would be accessable with everything back in place. See pic below. This enables me to sit a DVM on the floor and monitor various ECU inputs and outputs with the car running or under load. I can now see exactly when the 6PI and VDI is being told to open and all the thermo sensor inputs that may be screwing up my idle.

FYI...the square thing you see tie wrapped above the connectors is a laminated pin out of the molex connector and corresponding ECU terminal.

If you do not have a patent on this, I'm going to copy cat it. I have bought those devices at Radio Shack that you can patch a wire in to an existing wire. I then put a banna jack on the other end and monitor the signal. What you've done is superior. I know of the plugs you are using. I splice the whole engine harness on the salvaged turboii that I have. I never thought about using the female part of the connector in the fashion that you are using it. The throttle position sensor, 2g, is an interesting one to watch. Should be 1v at idle. I took my water thermostat out and noticed that the thermowax never lets the fast idle cam come completly off its ramp, which results in the 1v out put at idle of the tps to always read high. Even here in Texas where the temp is 100 degrees. Kudos for the break out plug that you made.

It's been very interesting to watch the voltage levels on a DVM while driving around town. The first one I've found that looks bad is the engine thermosensor. It constantly sits at 3v, with the key on, at idle or after a hot run in the FL sun. It should vary based on temp and according to the manual should be between 1v to 2v with the engine at idle (176F).

I've been going through each pin and looking at the input or output voltage and comparing it to the chart in the manual. I'm determined to find out why the car stalls with the AC on. Interestingly enough it was fine since installing this connector and cleaning things up...but it's too soon to celebrate. I need a warmer day to be sure.

Here's a pic of the harness before it was installed in the car. The spiral wrap is really nice because it lets you pull wires out at any location and is reversable. I was only intereted in 18 signals, so I have a few spares in the connector.

I took this picture before I undid all the spiral wrap and added the aluminum foil tape as an EMI shield. I put the wrap back over the foil taped wires.