Yeah, I forgot to mention that part. Sorry about that.
See, what they do is actually plug a scanner into the OBD port and drive the car around. The shop that I have dealt with the most uses something like the Snap-On MicroScan, but it is a little different. Sorta looks like an older model, but all that is besides the point.
The point is, they will plug this thing in and drive. They wait for the car to exhibet any problems, such as your O/D Light blinking, and the system will actually record all readings from the ECM for the last 15 seconds or so of operation. They can then, once back at the shop, see what the code is and check out what was going on at the time the malfuction occured.
Thing to keep in mind here. This could take some time. They will actually have to record something before they go tearing into it. I hope they would anyway. One time I had to leave my car at the shop for three days before the symptoms returned. As a matter of fact, I actually had to tell them what I would be doing and how I was driving for the symptoms to show themselves. They actually used my car to shofure customers around town and to run erruns. Like if someone needed to go get lunch or something, they would take my car. So keep all that in mind with this and good luck.
