Timeline for How to test a bolted-in heavy duty 50a / 80a / 100a fuse with a multimeter without removing it?
Current License: CC BY-SA 3.0
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| May 3, 2016 at 14:18 | comment | added | cdunn | Yes, but you can test for that by grounding the negative cable of the tester and making sure there's voltage. Bottom line, it's about understanding what you're doing and why, not following a script. Fred is right on about testing for voltage. There are several ways to do that, and as long as you understand how it works, you'll do the right test. | |
| May 3, 2016 at 13:20 | comment | added | Dan Ross | @cdunn mind you, if the fuse isn't getting any voltage in the first place because of some other problem, even with the battery connected, then a bad fuse would look the same as a good fuse: ~0 volts across it. | |
| May 3, 2016 at 3:54 | comment | added | Cort Ammon | Agreed. There are some annoying circumstances where there could be a short across the fuse via the body of the car. Usually that's not the case, but not surprisingly, the presence of a short across the body of the car has a curious tendency of blowing fuses.... testing voltage when the power is on will not be fooled by this second path between the two sides. | |
| May 2, 2016 at 20:49 | comment | added | cdunn | I agree, testing the voltage on the fuse is the best way to go here. You can even put the positive on one leg of the fuse, and the negative on the other with the meter in the volts position. If the fuse is good you will get a very small voltage across it. Much less than one volt (millivolts to maybe a tenth of a volt). If you connect it this way and get + or - 12ish volts, the fuse is toast. | |
| May 2, 2016 at 19:26 | comment | added | Ben | @user568458 it won't damage the fuse but voltage drop is a better indicator of fuse health and doesn't require removing the fuse/disconnecting the battery to test. | |
| May 2, 2016 at 19:15 | vote | accept | user56reinstatemonica8 | ||
| May 2, 2016 at 19:15 | comment | added | user56reinstatemonica8 | Great, I was really hoping they were designed for the purpose! I can see the advantages of using voltage but is there any reason to not use Ohms if the battery is disconnected already? e.g. Could it damage the fuse? | |
| May 2, 2016 at 19:11 | history | answered | Fred Wilson | CC BY-SA 3.0 |