'78+ wiper switch in a '77 ???

[SkinnyG]

1977 switch seems to be a unicorn.

Is there any reason why I cannot adapt a 1978 and up switch to my existing 1977 truck wiper system?

[ray_mcavoy]

The 73 - 77 wiper motors have an internally wired park switch. In 78, GM changed to a permanent magnet wiper motor that has an externally wired park switch.

As a result, the truck's wiring and the electrical contacts inside the 78+ wiper switches are configured differently to work with the externally wired park switch on the 78+ motors. I don't think you would be able to keep the parking function if you were to adapt a 78+ switch to a 73-77 wiper motor. Without that, the blades would stop the instant you turn the switch off ... you'd have to time it carefully to get them stopped at the base of the windshield.

There are some NOS (new old stock) 75-77 wiper switches still available. Here's an example --> http://www.ebay.com/itm/NOS-75-76-77...-/272066235155

The other alternative would be to convert everything (switch, motor, and wiring) over to the 78+ setup.

[SkinnyG]

I see. Alrighty.

Thanks for the link - I'll look into either NOS switch, or hunting down 78+ with interval wipers.

Thanks.

[mcmlxix]

Will a newer wiper motor bolt up? Can you can upgrade the switch and motor?

[USSkoval]

You can swap to the newer style, but you basically need everything from a donor truck including the harness. I spliced in the correct pigtails and ran the needed extra wiring, but swapping the harness might be easier for some people.

[SkinnyG]

Modifying the wiring is no problem for me. I just like to explore the easy/cheap fixes first.