I am going to assume that your 115 is set up similar to my 123. The switch under the pedal operates a solenoid at the right rear of the transmission. On my 123 the wire had worn in half and then shorted out to the frame. I replaced about an 18 inch section of wire and put plastic loom around it to protect it in the future. Car will now downshift fine when you floor it. Still slow off the line, but that is the nature of the beast. BTY, the fuse for the downshift was one of two that ran the climate control. I ran the car with the switch under the pedal unplugged for awhile because every time I floored it, the car went into the failsafe defrost mode because the fuse blew.