Screen Washer Pump Problem

[Chuffer]

I have an electrical problem on my 1980 C3 that is driving me nuts . The screen washer pump packed up , so first I tested out power supply from wash / wipe switch and got 12 .5 volts at terminals with engine running and washer switch activated . Removed pump and tested out with `fly leads` made up and connected direct to battery . Pump was `dead` .
Bought new pump and checked it worked before installing . Connected to wiring and still will not work . Re checked power supply and still had 12.5 volts .
The multi function switch operates wipers in all modes including sweeping screen when washer mode is activated but get no squirt ! Any suggestions please .

 

[curious bystander]

Bad earth?

 

[Chuffer]

As one of the two wires must go to earth somewhere , my thinking is it`s not an earth problem as I get full voltage reading across the terminals or am I wrong ??

 

[curious bystander]

Are the wires connected to the pump the wrong way round? Clutching at straws here Mike

 

[Chuffer]

I am still hanging on to my straw to no avail , It is connected right way round but on test pump works either way round , I guess it just blows instead of sucks !
Thanks anyway Bill.

 

[kentvette]

Not sure how simialr the opperation is by 1980, but on our '78 the switch closes the earth connection, so I'm assuming the power supply to the pump is "hot" all the time the ignition or "accessory" is switched on. But, it seems to be the same actual earth route as the rest of the system and goes via the instrument lights earth.

As Is ay, that may not be relevant by 1980, as I think your wash/wipe/delay module is all different!

 

[Chuffer]

Power supply on a 1980 is `hot` , its the yellow wire on mine and my understanding is all the functions on wipers are activated via earth . I replaced the old wash / wipe / delay relay about two years ago because it was giving trouble and fitted updated pulse unit instead and washers worked then . I just can`t understand why I get full voltage when switch circuit is `closed` ie : operational but nothing happens when pump is connected.

 

[teamzr1]

Power supply on a 1980 is `hot` , its the yellow wire on mine and my understanding is all the functions on wipers are activated via earth . I replaced the old wash / wipe / delay relay about two years ago because it was giving trouble and fitted updated pulse unit instead and washers worked then . I just can`t understand why I get full voltage when switch circuit is `closed` ie : operational but nothing happens when pump is connected.

Can you post here a wiring diagram for the WW ?

 

[kentvette]

Power supply on a 1980 is `hot` , its the yellow wire on mine and my understanding is all the functions on wipers are activated via earth . I replaced the old wash / wipe / delay relay about two years ago because it was giving trouble and fitted updated pulse unit instead and washers worked then . I just can`t understand why I get full voltage when switch circuit is `closed` ie : operational but nothing happens when pump is connected.

Could it be a break in the wire close to the pump? Are your testing by connecting to the actual "spade" connectors that would attach to the pump?

 

[Daytona Vette]

I have not quite followed all this, but if you are saying pump is not jetting water but elec connections are sound - could it be that you have a one way non return valve in the supply tube that is in the wrong way round.

 

[Chuffer]

Hi Guys , thanks for all the comments and suggestions . To answer the last three posts : (1) I don`t have a wiring diagram I have just researched feeds and cable colours from the internet.
(2) I have been testing at connector terminals to get 12.5 volts reading so it`s not a break in cables.
(3) No one way valve fitted in supply tube as they used to work . The pump will not even spin over .

 

[67HEAVEN]

...I don`t have a wiring diagram...

You do now...

 

[teamzr1]

Maybe this will help though may be different if the car has the pulse delay wiper design

 

[curious bystander]

Well that should sort it easily enough Mike
Or maybe Halfords have a toggle switch - one wire to the pump and the other side to earth?
More seriously is the dashboard multi function switch working correctly? When you switch on the washers does it complete the earthing circuit?

 

[Chuffer]

Thanks teamzr1 , that is a great help now I`ve realised its not a map of the London Underground ! Time to start more investigations .
And yes Bill ( curious bystander) I did considder the Halfords toggle switch route .
Hopefully my next post will be on of great joy and celebration .

 

[Nick B]

I've always admired people that understand wiring diagrams!

 

[teamzr1]

Chuffer
You need to state which W/W system your Corvette has
The 2 wiring drawing I show are for each

You need to know if yours has the intermittent wiper or
the delayed pulse ( has a slider switch on dash to adjust)
and then use only that drawing

How many wires plug into the washer pump ?

 

[Chuffer]

Hi teamzr1,

I have intermittent wipe operated by rotating the up / down switch lever for mist, normal , fast wipe functions .
The plug has two wires.

 

[teamzr1]

OK so now knowing which your Corvette has
I made the wiring drawing easier to follow

1. Not think it is the problem but check both fuses.
2. Disconnect the wiring connector from the washer pump
3. With ign switch in ACC mode, use a multi meter on volts and check pink wire for 12 volts other side of meter to chassis ground
4. Now switch meter to OHMs
5. With ign key off
6. Check white wire with meter to ground, if ign key off then ground (I set in green) should be open
7. Now with meter still connected as #6 push washer switch and meter then should show going to ground

If there is 12 volts to pink wire going to pump then somewhere from chassis ground to ground to pump is the issue
could be the washer switch so check for ground between washer switch (pink wire) and the controller
and then white wire from controller to washer pump

 

[Chuffer]

That`s brilliant Thanks a lot . I will give all a try when I get the chance.