Remember when all you needed was an old screwdriver to start an engine from under the hood? Add in a 1/2 and 9/16 wrench and you had your tool kit for any vehicle? My God am I old!
yeah, not to hijack my own thread here, but that brings back to mind the 4runner story because it's a perfect example of the opposite of a vehicle you can fix with a couple of wrenches and a screwdriver.
I learned through this experience that over time, the communication protocols used by OBD2 ports have changed. Most generic OBD2 scanners start with the earliest protocol, and if that fails, they move on to the next, until the find one that the vehicle responds to.
On a 2004 4runner, there is a sequence of short and open across a particular pair of pins that deletes the calibration data for the sensors used by the traction control system, and that sequence also occurs during the connection process for one of the newer protocols than the vehicle uses. As long as the correct protocol succeeds, no problem...but if for some reason the scanner fails to establish communication using the correct protocol, the next one it tries will delete that calibration and cause the traction control light to illuminate and the TC system to deactivate the instant your vehicle moves. I connected to it to clear an O2 sensor code after replacing it, and afterward the TC system shut down. I had to first scour the internet to figure out what the heck happened, find that Toyota had published a TSB for it, and then get a couple of paperclips and made a jumper wire so I could complete the sequence to recalibrate the sensors.