I have a friend who is getting on the older side. He was taught by his uncle to flip a switch on the dash to put it in overdrive. This isnt the normal way to connect an overdrive. Fords have a switch on the accelerator pedal. Chevys have a bracket on the carb actuating when the accelerator linkage hits the switch. Normally anyway.
So my friend has this problem. He forgets to flip the switch! No big deal you say? When you put it in reverse with the switch activated, it ruins the transmission! I hope Fred or someone can explain what happens. Its a very expensive fix. So, please hook it up using the correct wiring diagram or you will be at the trans shop more than driving the vehicle! I call him about once every few months offering to fix that. He says I will be there, then a few trans fixes later, I call again.
