It's been a while since I've been able to post. I have several to post and I'll start with this one. This is a 1994 Ford Taurus Wagon with the 3.8. The customer brought it in after working on it himself since before Christmas. Basically, after many repairs and swapping parts, the original concern was still present. He gave me a list of all the parts he had replaced: fuel pump, fuel pressure regulator, ECM, CCRM, Coolant Temp, Ignition Switch . . . etc. He had tested the grounds several times and had found no problem.
The symptoms were when he would turn the key on, the cooling fan would come on immediately and the fuel pump would run continuously and not cycle after two seconds, and he could not get his code reader to communicate with the ECM. From that description, I felt something was going on with the grounds: either with the ECM or its contacts or a ground on the vehicle.
I knew from other repairs a common problem on these was the ground connector located between the battery and the radiator. Often times, when you unplug this connector (a two wire connector) it will be corroded. When I unplugged this one I saw no corrosion.
However, to be sure I jumpered the two wires (harness side) straight to the negative battery post. When I turned the key to the on position, the cooling fan did not engage and the fuel pump primed for two seconds and shut off. Also, my diagnostic machine would now communicate. Presto!
I tested it some twenty times or so and each time it worked as designed.
I spliced two good wires together and drilled a new ground contact on the body and put loom around it.
I again tested it several times and each time it worked properly.
Here is a look at the orignal connector.
Apparently, the wiring on the ground side (in the picture the longer wires) was faulty and not allowing the ECM to have a good ground; hence, the running of the cooling fan and the fuel pump without cycling off after its prime.
Again, sometimes it's the small things that make a big difference. After telling the customer of the repair, he told me he had probably unplugged and plugged in that connector numerous times. It did look okay, but upon testing it was faulty.