Car Electrics. Stumped beginner.

[leadfootlydon]

I have a voltmeter aka DMM. I understand amps and watts. What I cannot understand is what to do when there is no exposed bit of metal for me to put the probe on.

I am wondering if you are supposed to pierce the insulation with the stupidly sharp ends of the probe, or is that a no-no?

Or maybe there should always be a way to insert something compatible into the female part of a connector (after struggling mightily to get it apart without breaking it). But then again, the fact that the component is no longer connected has changed the circuit anyway. So...

What's the trick to tracing a voltage level or continuity down a grimy old set of wires?

[Penelope Stopit]

You've got it, no prodding of the insulation

insert something compatible into the female part of a connector, is the way to go when all else fails, using a jump cable to keep the circuit complete

The thing is, older cars don't have sealed plugs, measurements can be taken from the rear of loom plugs/sockets, at fuses and relay sockets to name a few

Good innit

[GreenV8S]

Insulation piercing probes do exist, but you'd only use them as a last resort and would need to repair the insulation afterwards to avoid corrosion damage. There are various back probes designed to be inserted into the back of a connector in the gap between the wire and the housing. Sometimes there's enough space to put an ordinary contact probe in there.

[Mroad]

T pins into the back of the connector is the 'official' way (or metal paperclip) if your meter probes won't play ball. Obviously make sure anything stuck in a connector doesn't short to other circuits or the body after inserted.
Don't jam probes into the front of disconnected connectors as it can spread/bend the clamping teeth too far apart leading to problems when it's reconnected later on.

You can pierce the insulation if there's no better way, you can get piercing probes specifically for that but really need to seal holes afterwards to prevent moisture ingress and corrosion. Liquid Tape is an easy fix for sealing up holes in insulation and won't fall off like normal electrical tape.

[leadfootlydon]

Ok. Good. I understand that piercing the insulation is a last resort. I will look harder for ways to get access to the conductors/connectors.

Thanks for the clarification.