Actually, it only took a half-hour to fix switch, but it took two hours to finally decide that that was the problem, remove it, and then reinstall it after the rebuild. When both the gas gauge and the wiper stopped working, I jumped to the conclusion that GM’s construction of the switch uses a pot-metal (soft) housing retaining the plastic, copper, and steel of the switch’s internals, contacts, and connectors. The basic function of the switch is to connect combinations of blade connectors to the housing, and, thus, to ground. This completes different 12 volt circuits running through the wiper motor causing it to spin slow or fast. As I posted before, when I was installing the clutch pedal, I had to undo all the wire bundles under the dash. I surmise, then, that I yanked on the wires going to the switch, causing the contact-to-housing connection to fail. I ended up removing the switch from the dash, disassembling it, cleaning the contacts, coating them with di-electric grease, stacking all the pieces back into the housing, and then crimping the housing to the insulator making sure I caused the housing to touch the correct contacts within the switch.
With the switch back in place and the wipers wiping again, I turned my attention to the other dash-mounted failure – the gas gauge. I removed the screws retaining the heater controls and pulled it out of the way to give me access to the back side of the gauge. I then pulled off the connector, turned the key to ON, and measured the voltage at the tan wire – 12.4 V which just happens to be the reading on the voltmeter that’s bolted under the dash. Therefore, the sender is still connected to the gauge, but providing no resistance to the electron flow, indicating – to me – the float is on the bottom of the tank even though the tank is full of gas.
Given all the time I wasted on these two projects, I didn’t have time to do anything more on the car that evening.