Ground side switch ok for washer pump?

[Creedmoor]

68 Fastback, 2 speed wiper motor. Never had working washer pump in the 15 years I’ve owned it. Never needed it. Got a bee in my bonnet to make it work. Don’t know if it used to be manual foot pump or electric. Going to go electric. For a variety of reasons, wiring would be way simpler if I just make the momentary push button I’m installing switch the ground side. Any downside to doing it this way?

Since the car has a 2 speed wiper motor, I’m assuming the wiper switch was never set up to control a washer pump. It does push in slightly though. Any way to tell if it functions as a pump switch?

Appreciate any thoughts or advice.

Thanks.

 

[Mattax]

Heck everything is probably there from from the W terminal to the whatever cavity it goes to in the multi-connector. If there is continuity from the B terminal to the W terminal, or if the switch feed is hot thensee if there is power (12 - 14 V) at the W terminal when the button is pushed. If so its ready to go.

One way to know if the car was originally foot pump or electric is look at the plastic plugs in the firewall.

According to the diagram its a brown or brown striped wire and goes to cavity M.

 

[Creedmoor]

Appreciate the advice. But....

There is no W (washer pump?) terminal as there is no washer pump. I want to install a washer pump. Cavity W on the bulkhead connector is empty.

So back to my original plan and my original question:

Any issues to wiring a washer pump with a ground side switch?

Thanks!

 

[Mattax]

That switch doesn't have the W terminal then it doesn't have the push in feature.
2 speed '68 with foot pump. 2864415
Cavity W on the bulkhead is not for the Washer. Cavity M was.

Theoretically there shouldn't be an issue using a momentary push button the ground side. Issues I would think more will depend on where power is being drawn from.

 

[Creedmoor]

I guess I'm dyslexic or just retarded. I meant the M cavity is empty.

I haven't been able to get a needle twitch or a test light glow from any wires associated with the wiper swich. Sigh. Running my own wire then.
Yeah, I can't think of a reason a direct path power circuit would care at all if it was switched from ground or power. I'll fuse the ground side too. Just to be consistent.

Thanks!

 

[67Dart273]

I normally don't care much for ground leg switching, but now that we have all these EFI toys, ALL of them so far as I know use ground leg switching, because of the way the switching transistors are wired. Of course your dome lamps are ground leg switched. LOLOL BREAKER points are ground leg switched. AND, the 70/ later voltage regulator is ground leg switched.

 

[Mattax]

Should be info in the FSM on the two speed switch and wiper operation.
Using wiring diagram - whichseems to match the positions:
B is hot with key in run or accessory. That's power in.

A is armature
F is field (H for High)
P is park but whether that is useful requires looking at how that wiper system works. It may be hot whenever B is hot.

Wiper motor wiring


There's other people who have done what you want to do.

Post in thread 'Get rid of the manual washer pump'

Aug 10, 2020

I converted a mechanical foot pump bracket for my sons car. Removed the cup, cut out the bracket center, flipped the cup over upside down and tack welded it on from underneath. Then added a heavy duty pushbutton starter switch. Didnt even have to open up the center hole in the cup for the switch.

Running a stock A body electric pump and reservoir. Its only a 1 wire circuit. Run a single wire from the pump and pin it in at the stock bulkhead connector. Run it to the foot switch, and up to the fusebox for ignition switched power. The pump motor has 1 power feed, and is grounded to the...

• moparmat2000

 

[Inertia]

Yes. You can install switch on the ground side, like the horn.