Stupid Q amnesty - using a voltmeter to test a connection

[Paul]

Stupid Q for those in the know I'm sure...

My washer jets have packed up on my non-retro Corsa...no noise from the motor...fuse fine...

So I've unplugged the bottle - presumably I can test the plug to see if power is getting to the motor...?

What am I looking for on the multimeter? And should I have someone in the drivers seat turning on the jets?

[colnerov]

Hi, Yes...12V...and yes.

Colin

[fad]

^that^

Test at the socket using the "Volts" setting with someone operating the switch. NOT the end that goes to the washer pump (folk have done that before, disconnected and then tested the wrong bloody connection).

If you get nothing there, then (assuming a 2-prong plug) test between each pin and a GOOD earth on your chassis or engine somewhere with someone operating the switch for the pump (you can test for a good earth by setting your meter to read resistance (Ohms) and test from whatever you select as your earth and the battery negative post - if it reads 0, then that's a good earth, If it reads a number (say 500 Ohms or so), it's a dirty earth, if it reads a very high number (mega ohms), find somewhere else - scratch at the point you have selected with the prong to create some fresh metal on both the battery post and the point you select as earth).
If you still get nothing, then you know that there's no power getting to it. If you get +12v between one of the pins and chassis, but not between the pins, then it's a bad earth or a buggered connector.

I am going to say, without looking, that your pump motor is likely the culprit. To test this,improvise, adapt and overcome a wire bridge between the pins in the plug that go to the washer pump. Identify which is + and which is -. Stick them on your battery. If the pump fires up, the problem is obviously inboard. If the pump does nothing, then you know it's the cable or the pump.

*NOTE* DO NOT USE THE CURRENT (AMPS) SETTING DURING ANY OF THESE TESTS. Also, there's no need for someone to operate the switch when checking for a good earth, and when you are checking for the earth please don't stick the meter on the positive post of your battery.

[Paul]

That's really helpful...can you believe I have an 'A' in GCSE Electronics :-)

[fad]

Jan 30, 2017 13:55:38 GMT Paul said:

That's really helpful...can you believe I have an 'A' in GCSE Electronics :-)

No. I can't. LOL

[ChasR]

What year is the Corsa.

If it's pretty new beware that modern CANBUS stuff will shut things down if it feels there is a short present.

It may be worth testing the motor itself (with care) from a 12V power source.

[Paul]

It's a 2002 if memory serves...not that modern. I'm swamped with work ATM so have already gone ahead and bought a spare motor (they're about £6) - although I'd much rather take a systematic, logical and thorough approach to the problem ;-)