Multimeter leads won't reach opp. sides of car - PeachParts Mercedes-Benz Forum

Fritz · #1 02-15-2006, 03:06 PM

Hi, everyone.

I suspect I have a few bad glow plugs and am trying to diagnose the problem.

I need to connect my multimeter leads to the neg. battery terminal and the glow plug relay. However, the leads that came with the multimeter are too short.

I have found lead kits online, but many don't specify the length of the leads, and they also seem very expensive ($20 leads for a multimeter that cost $15). Can anyone recommend local chains where I can find longer leads?

#2 02-15-2006, 03:10 PM

The negative battery terminal is ground. You can connect your lead to most anything metal that you can find in the engine compartment and it will be the same reference point.

Good luck,

rhodes2010 · #3 02-15-2006, 03:11 PM

Why not use any kind of wire ?
I needed the same thing last week and used solid copper 4 strand
phone wire.
A different time I used some speaker wire.

Especially for really long runs, like when I want to read the meter
while sitting in the car.

You can choose to alligator clips if you plan on doing this a lot.

Fritz · #4 02-15-2006, 03:37 PM

Thanks, Larry. I'd forgotten this from physics class... I believe I need to refresh my basic knowledge of electricity.

rhodes, that's a good idea as well. I'll probably just fashion something out of regular copper wire if I need this kind of application in the future.

Mike Murrell · #5 02-15-2006, 06:18 PM

I'm curious.

If you were to lengthen the leads, would you now create more resistance(ohms) and skew the readings?

Been a long time since my last physics class as well.

#6 02-15-2006, 07:31 PM

Lengthening the wire the distances we are talking about here will not create an appreciable resistance.

Have a great day,

bhatt · #7 02-16-2006, 02:49 PM

Test the wire for resitance from one end to another. Then just subtract that number from each of your meter readings.

For example, if you measure the wire as having 10ohms resistance and then test out a glow plug and get 50 ohms, the actual resistance of the plug is 40 ohms.

Neal