Hello all

The windshield washer has stopped working and I've already ordered a replacement washer pump, but out of curiosity and green thinking and also worried that maybe the issue is somewhere else, I wanted to check if there is more that I can do.

I've connected a multimeter to the plug from the battery and it correctly shows 12V when the ignition is on and I pressing the lever to spray water. When I do it with the pump connected it makes no sound however.

Is there a possibility of another issue somewhere? Can I open up the old pump to check what's up inside?

Thanks. 

fit a light bulb to the wiring socket...does it light when you operate the stalk ?

 

if yes its the pump at fault...theyre very cheap to buy

I haven't tried with the light bulb, but it shows 12V on a multi-meter when operated 

try a pump then...the light bulb test proves the wiring can carry sufficient amps to work the pump   

It will take another week or two for it to arrive. I'm trying to expedite the diagnosis in case it isn't solved with a new pump

It is a common misconception, that if a voltmeter or multimeter show 12 volts, then the wiring must be good.

The problem with using only a voltmeter/multimeter, is that, if there is high RESISTANCE in a circuit, then the meter will still read 12VOLTS (or more correctly, battery voltage)

Having battery voltage there is good, BUT - if there is high resistance, then the CURRENT (AMPS) will be restricted and the pump (or whatever unit is connected) will either not work at all, or will not work efficiently.

 

It is for the above reason that Steveo has suggested that you use a bulb (test light)

I would recommend that you use a fairly large bulb such as a 21 Watt bulb (brake light bulb or direction indicator bulb) - A very small bulb might not put enough load on the circuit.

Before you check the pump circuit with a bulb, connect it to the battery and note how bright it is - When connected in place of the pump, it should give about the same brightness, anything less would probably indicate high resistance in the circuit.

 

You can prove the above for yourself with a simple calculation, known as Ohm's Law:

Imagine a 12v system with a current of  (say) two Amps flowing through it. If you divide 12v by 2Amps, it will give you 6 Ohms (resistance)

If you were now to double that resistance to 12 Ohms you would cut the available current in half to 1Amp.

Corrosion or a dirty connection in the circuit would have exactly the same effect on your pump.

 

Regards

Thank you for the reply. I have replaced the pump and it works now.