Here is the deal I have converted an 87GT to MAF using parts from an 89GT doner car. We used the ECM harness, MAF and ECM. After installing the new harness to our suprise we had no fuel pump. After a bit of digging we found that we had no power to the realy got that fixed added the moniter wire for pin 19 and both of the wires from the speed sensor. We then found that the harness that goes to the drivers side of the car (entering the car) is pinned differnt. I have gotten all of the gauges working but still have a few problems. The trans sensor will not work properly ie: will only start in reverse and back up lights are on in park. and car will not do a KOER test. (using Snap on MT2500. Runs like crap at idel loading up and now getting a code 63 but the voltage is with in range with a perfet slope. (vantage meater) any Ideas????????????

 

The car won't run the KOER until the 63 is fixed. It won't let it run it until then. The 63 means the voltage is low or the TPS sensor is unplugged. If it is has the correct voltage, then I don't know what to tell you. Other than not to drive it until you get it fixed. I attached a diagram for this. 26,46, and 47 are the wires for the tps.

http://www.veryuseful.com/mustang/te...ng_Diagram.gif

The problem with the back-up lights and safety switch both come from wires on the transmission. All I can tell you is to look at a diagram and chase wires to see where they are crossed.