Power to Windshield Washer Pump

[rickmraz]

The two wires that power the windshield washer pump in my 1972 240Z are always hot. Voltmeter reads about 14v. Pressing the washer button on the multi-function switch doesn't change the voltage.

Suggestions on the source of the problem?

- Bad multi-function switch?

- Short in the wire harness?

- Is 14v the correct voltage to power the pump?

-rick

IZCC #7509

1972 240Z

1982 280ZX

[MikeW]

The two wires that power the windshield washer pump in my 1972 240Z are always hot. Voltmeter reads about 14v. Pressing the washer button on the multi-function switch doesn't change the voltage.

Suggestions on the source of the problem?

- Bad multi-function switch?

- Short in the wire harness?

- Is 14v the correct voltage to power the pump?

-rick

IZCC #7509

1972 240Z

1982 280ZX

I would guess there's a problem in the switch. The washer part of the switch is quite simple. I can take and post some pictures if it would help you.

There's really only one voltage level in the car and it should be around 12 volts. What does your meter read right across the battery? Is this with the car running on not?

[EScanlon]

Mike makes a good point on the switch, but it could also be related to the Map Lamp, the Dome Lamp and switches as well as the wiring for the "room lamps" (courtesy lamps not installed originally, but wiring is there) as well as the Glove Box lamp. Interestingly enough the Key In Buzzer and Switch are also on this circuit.

But you DO have a problem, as continous power to the WW pump will not only burn out your motor, it will also empty your tank quickly....and we don't want your Z weeping all over the road. ()

E

[rickmraz]

Mike, E,

thanks for the help. The ~14v at the plug was with the car running. I will check the switch. I pulled a switch from a '72 from a junk yard a few months ago so I might do a quick swap to see if the problem remains.

I will post an update after my troubleshooting.

-rick

[Arne]

But you DO have a problem, as continous power to the WW pump will not only burn out your motor, it will also empty your tank quickly....and we don't want your Z weeping all over the road.

No fears about killing the pump, he mentions he has power to "both" leads. The washer pump is not grounded to the body. One of the two leads should supply power, and the other ground. (Can't remember which is switched in this case, the power or the ground.) If both are powered, the pump ain't gonna do nuthin'.

On further thought, it seems to me that my washer pump has a black ground wire and a second wire that is only hot when I press the button. Can't say for certain though - I'm at work, the Z is at home. (Motorcycle commuting! woo hoo!)

[EScanlon]

Arne;

He didn't mention if he was checking each wire's voltage to ground, so I presumed he was checking them against each other, that being the "obvious" test. Not too many people would know to check each wire against ground, as that is a bit more advanced electrical knowledge. That's why I presumed that he'd have continuous power. But...you may be right, in which case he has some SERIOUS wiring issues.

E

[rickmraz]

I spoke with Todd Wagner from TideWater Z. He said the pump has continuous power and the ground is switched.

We looked at the simple push button switch. Looks like two copper strips are grounded to the steering column when you press the button.

I already think I know what my problem is....

- I could not get the turn signal switch and multi-function switch to tighten against the steering column. They seemed to have a little play.

- I cut a piece of closed cell foam to act like a spacer or gasket so I could tighten the switches against the steering column.

- I bet the foam blocks the push button, copper strips from grounding against the steering column.

I am traveling this week. I will post another response when I get home.

-rick