1969 Windshield Wipers

[Bill Stephens]

I recently changed the blower motor and heater core on my 69. When I was testing to be sure everything worked on reassembly, I discovered that my windshield wipers no longer worked. I don't know whether they were working before I changed the blower motor because I haven't used them in several months. They were working the last time I used them.

When I hit the wiper switch I get a clicking in the relay, but the wiper door doesn't open and the wipers don't work. If I use the vacuum switch below the steering wheel to open the door, the wipers still don't work. The center knob below the steering wheel that cuts power to the wipers is open.

The ground that the wiper motor shares with the blower motor is connected and the blower motor works fine. I've tested the connections with a test light, and the yellow and green wires going into the wiper motor three connector both have current. The light blue does not. The two prong connector with the yellow and dark blue wire is not connected to anything, although the yellow wire has current. The washer was removed before I bought the car and I suspect these are supposed to go to that, although it is impossible to tell for sure from the wiring diagram.

I think I may have some kind of ground problem because I got a small spark when the metal centerpiece of the dash rested against the shifter knob. The problem is that the ground wires seem to be connected.

I'm running out of things to try. I don't seem to have disconnected any of the wires when under the dashboard. Is there anywhere that describes how the system works to help troubleshooting or are there common problems with these systems that I should check? Any suggestions would be greatly appreciated.

[Jack H.]

Re: 1969 Windshield Wipers

Try reading your copy of the '69 Chevrolet Chassis Service Manual. There's a nice section there on windshield wipers and it specifically makes address to the Corvette with it's wiper door system.

Basically, the system is part vacuum and part electrical and there are safety interlocks. Power is prevented from being bussed to the wiper motor until the wiper door raises to its up/open position. On shutdown, the vac actuated wiper door is prevented from closing until the wiper motor has shut off and the wiper arms are in down/parked position.

Under the steering column there are over-ride switches. One forces the headlight doors up to facilitate changing headlamp bulbs. The center turn knob cuts power to the wipers allowing you to 'halt' them in mid-sweep to change the blades. The other vac switch forces the wiper door up as a convenience feature for driving in mist conditions (why open/close/open/close the wiper door to sproadically wipe the glass?).

Last, if memory serves, there's a Jim Dandy troubleshooting chart in this section for the windshield wiper motor allowing you to troubleshoot both on the car and on the bench based on failure symptom.