Author Topic: Multimeter accessories for vehicle testing....any tips from professionals?  (Read 3902 times)

Offline machinisttx

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As much as I hate electrical work on vehicles, I'm finding that I need to diagnose such problems more frequently. I have several good multimeters, but not much more than the standard probes to go with them. Are there brands to stay away from when buying accessories like back probes, etc.?

Offline MontanaBound

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Re: Multimeter accessories for vehicle testing....any tips from professionals?
« Reply #1 on: November 15, 2015, 07:04:05 AM »
I just use T-pins that you can buy at craft store etc. then just hook on to them with alligator clip probes. Im thinking the list of what to stay away from would be much larger than the list of whats good. Really just keep in mind that you get what you pay for.
When using t-pins I don't recommend puncturing wires tho unless its an emergency, use them to back probe. Dont force them into terminals either as this will create more problems than you already had.  :)


Offline Carl

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Offline shadowalker_returns

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Re: Multimeter accessories for vehicle testing....any tips from professionals?
« Reply #4 on: November 15, 2016, 09:36:46 AM »
As much as I hate electrical work on vehicles, I'm finding that I need to diagnose such problems more frequently. I have several good multimeters, but not much more than the standard probes to go with them. Are there brands to stay away from when buying accessories like back probes, etc.?

Hmmm. This thread is old but I feel I must respond.  :D 

Its stated "I have several good multimeters". I must ask do they say Fluke on them? If not then all you have are "several multimeters". Hold on don't shoot me yet.. I don't work for Fluke. I do have 40+ years experience in electronics. I currently own a Field Service company that specializes in the most high end of medical devices and worked on Air Search and Fire Control Radars for much of my career. When a competent mechanic tells me they hate electrical work I always ask to see his/her tools. What I find is they equip themselves with the best mechanical tools they can currently afford and the cheapest electrical/electronic tools they think will get the job done.

Electrical/electronic work is not inherently intuitive even to those who have extensive experience, skills and abilities. Like anything it takes time to gather knowledge and experience. Over the years, I've found that mediocre test equipment has been the primary cause of failure to diagnose for more than a few mechanics. I've also found that overall the absolute best bang for the buck are Fluke Digital MultiMeters (DMM). You can trust their products to perform as stated and you can trust their calibration certificates. Many other brands will not or can not supply calibration certificates for their DMMs. Fluke is the standard I use to evaluate all other DMMs. Most come up short. You can spend $50-100 on a DMM and think you have a good meter or spend $150 on a Fluke and Know you have a good meter (if you only spent $20 or less for your primary DMM, go slap yourself  :P).

On the question of probes. When you purchase a DMM you are in fact buying a test and measurement system. This system consists of the meter, the probes and the cabling. For this reason its best to source all three from the same manufacturer. Its not an absolute but it is the best solution. the next best is to understand the individual components of the system to make an informed choice.

For vehicular service you want four types of electrical probe:
1) Standard Probe (pointed Semi-sharp)
2) Alligator Clip Probes
3) Piercing Probes
4) Back Probes
You will also want an AC/DC current probe and a thermocouple probe.

For Piercing and Back Probes its best to buy a pack of multiple probes. here's why. When you use these probes over time they can develop burrs and rough spots that cause the insulation to be torn through instead of cleanly pierced. Many insulations can recover and reseal when cleanly pierced but will not reseal when torn. The tear creates a point for moisture intrusion and eventual failure. When you purchase cheap probes (or any probe) run your finger along them and feel for the burrs, take the burrs off before you use them. The other problem are cables. The better meters usually are designed to work with certain types (quality) of cables. It seems non-important until you start doing capacitance or very low level measurements. The meter has to be able to compensate for the qualities of the cable. Most all Fluke DMMs can do this. Many of the less expensive meters cannot.

For about $100 you can get into a basic Fluke 101 and a full complement of leads. For about $180-200 you should be able to get yourself into a 113, 115, 117. I consider the 117 as a minimum for the Professional or competent amateur. For about $250-270 you can get Flukes Automotive meter. I swear by the 87 for serious field work (and most lab work as well). The Fluke Back probes were one of the best $35 purchases I've ever made and highly recommend them regardless of the brand of meter you use. Flukes Probe kits and Silicon cables are a bit pricier than the cheap stuff but worth it in the long run (they are also easier to keep professional looking for those in the biz).

Given the nature of modern vehicles its become mandatory for mechanics to embrace the electrical/electronic world. Don't handicap yourself with mediocre test equipment. Get the best you can afford. At this time (nov-2016) Fluke and their accessories are the best for the money (IMO others may vary  :o ).

Regards,
Shadowalker

Offline machinisttx

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Re: Multimeter accessories for vehicle testing....any tips from professionals?
« Reply #5 on: November 15, 2016, 06:37:21 PM »
I could send all the extra micrometers I have here at the house out for certification against traceable NIST standards. I don't because anything I'm doing here at the house isn't worth all the extra expense, and I'm perfectly capable of checking and adjusting them them against certified standards myself. That also needs to be done at least every few months to have any guarantee of continued accuracy. I could print out a certification of accuracy for every part I machine at work. I don't. Are the parts that don't have a fancy piece of paper with them any less "good" because they lack that piece of paper? No.

If you haven't had(and continued to have) your DMM checked against certified, traceable standards at set intervals of time then you have no basis to claim any other meter is less accurate, or less able to maintain that accuracy over it's lifespan. Also, I trust no instrument to be totally correct unless I verify it myself, nor would I trust their certificate....I'm pretty sure I've seen some of those guarantee certificates in with $5 chinese DMMs too. Yes, I hate electrical work. It's not because of tools, it's because it's so damn frustrating in general to spend a bunch of time trying to isolate a problem, which is often intermittent and not repeatable.

http://eu.flukecal.com/blog/understanding-basics-digital-multimeter-calibration