The Stovebolt Site Forums The Shop Area Interiors Windshield wipers

Hello all. I have a 56 3100. When I use the windshield wipers and then turn them off, they don’t. I thought there was an electrical switch in the dash and it was loose, allowing the switch rotate instead of switching to the off position. Needless to say, almost lost a finger. So now that I know it’s a mechanical switch, can anyone tell me how it works and ideas on how to fix the problem? How does the steel cable coming off the switch activate the wipers? Where does the electrical portion of the switch come in? Thanks. Thomas

Thomas,

I have moved your post and question to the more on-topic Interiors forum where folks can reply and offer some help and info on your question.

Pretty sure someone will come along and reply soon!

Dan

Thanks Dan.

IF you have an original electric wiper motor, the switch is inside the motor control, I thought 1/2 and 3/4 tons had vacuum wipers, was your truck changed to electric before you acquired it?

Original 56 and 57 wiper motors were vacuum per the parts listing. It also lists an electric motor specifically as a replacement. But even if it were originally electric or replacement electric, it would have a "park" switch inside the motor itself. The dash switch overrides that "park" switch to operate the wipers, and when the dash switch is turned off the "park" switch should interrupt power to the motor as the blades reach the park position.

Sfizio, you'll need to get under the dash and smack that the wiper motor. Percussive maintenance might fix it, but likely it'll need to be repaired or replaced, as the switch contacts may have welded closed or the linkage broken.
BTW, I like your signature. Molto bello!

My '57 LCF has electric wipers as that was original equipment for the big bolts. The knob on the dash has no electrical components, it is a cable from the knob that actuates the electric switch in the motor, all electrical components are integral to the motor. The 1/2 ton replacement motor might be different than mine.

I figured the electrical motor may have been something dealerships could swap. We lived in a mountainous area and a friend's father had one in a 1956 1/2 ton which had the electric wipers from when he bought it new. Good luck...buona fortuna! Much better than vacuum in the hills/mountains.

Sfizio:

What little there is about electric wipers in GMC trucks of the TF era starts on this page of the Maintenance Manual. It includes "wiper stopping operation".

I replaced the vacuum wiper motor in my '57 GMC with an electric Chevy motor. I think they are the same and know they mount and work the same.

Thanks all for the replies. Sorry for the delay, I’ve just seen them! Kind of lost track of the thread but found it today. I don’t think it’s a vacuum set up. The motor is strong and the wipers work well on either speed. If I rock the switch back and forth I can get the switch to contact the off position. I’m worried that contact position will fail eventually. It’s hard to get my head under there without taking out the radio, which I’m trying to avoid. (Why anyone one would cut a dash is beyond me). I can feel with my hand there is a switch component directly behind the knob with a steel cable jacket coming off it. The cable goes somewhere off in the direction of the wiper arms mechanism so I am assuming the motor is mounted directly behind the dash switch. Doesn’t seem very big. I’ll start searching the manual, thanks Bill, but if anyone can use my description to come up with any other ideas, I’d greatly sppreciate it.

tri five cars and trucks had vacuum wipers with electric as optional sharing the same cable operated switch. not sure the last year for vacuum.