how to test for good earth on the chassis?

[urS6Tom]

Be grateful for a bit of advice with what should be a simple installation. I'm fitting an Autospeed Intercooler Spray Kit and am having real troubles getting it to work properly. It may be that the control box from the kit is f*cked but I think it's more likely to be my wiring. The first thing I need to do is ensure I've earthed the pump properly. I've scratched away the paint underneath a nut that holds the washer bottle in place and attached the pump earth to that point.

My question is - how do I test that this connection is earthing the pump properly? I'm pretty new to electronics. Do I need a multimeter? What do I do with it?!

Cheers,
Tom

[mark_s2]

I would not use the washer bottle - it is plastic and therefore a good insulator.

I would also ensure that all the paint is clear on the chassis and a star washer is fitted between the chassis and crimp.

[urS6Tom]

I would not use the washer bottle - it is plastic and therefore a good insulator.

I would also ensure that all the paint is clear on the chassis and a star washer is fitted between the chassis and crimp.

Hi - thanks for the advice on the star washer. I'm not attaching anything to the washer bottle though, just using the bolt that holds the metal washer bottle mount in place.

But what about testing to make sure the earth connection is good? Is there a way of doing this with a multimeter or other instrument?

cheers,
Tom

[johne]

Connect a multimeter on a low DC voltage scale between any good earth on the car - not the one you've made but like the engine or battery -ve terminal and an earth on or inside the new unit you've fitted. Run the unit and if you get a reading of more than a few millivolts you're new earth is poor. The higher the reading, the worse your new earth is.

John

[urS6Tom]

Connect a multimeter on a low DC voltage scale between any good earth on the car - not the one you've made but like the engine or battery -ve terminal and an earth on or inside the new unit you've fitted. Run the unit and if you get a reading of more than a few millivolts you're new earth is poor. The higher the reading, the worse your new earth is.

John

Great -that's exactly what I needed to know. Thanks!