Back probing
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From: Seattle
Back probing
I remember what I wanted to ask you all. I came across it when testing the DPFE sensor the first time way back when. The manual indicated that when testing the voltages to the DPFE sensor I should back probe so that the circuit can still function during the test. Is a there a good way to do that, my buddy and I resorted to using alligator clips and jury rigged tab connectors and frankly I doubt we got a good accurate measurement.
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From: iowa
I don't use sewing pins, or other sharp objects to puncher the insulation, by doing this you are providing a place for moisture to get to the copper and begin corroding it, within a short time you may end up with a electrical gremilin, and when you trace it down you will find the wire is broke right were you probed it. If your going to back probe that means at the connector alongside the wire, most of the connectors have a rubber piece around the wires that will reseal itself to some extent or can me moved out of the way.
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From: Durham, NC
Originally Posted by monsterbaby
I don't use sewing pins, or other sharp objects to puncher the insulation, by doing this you are providing a place for moisture to get to the copper and begin corroding it, within a short time you may end up with a electrical gremilin, and when you trace it down you will find the wire is broke right were you probed it. If your going to back probe that means at the connector alongside the wire, most of the connectors have a rubber piece around the wires that will reseal itself to some extent or can me moved out of the way.
If you search the literature, there are lots of articles on probing through wire insulation, here is one for your reference:
http://autospeed.drive.com.au/cms/A_...popularArticle
Last edited by Bob Ayers; Aug 4, 2006 at 06:06 PM.
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From: Seattle
Thanks for the link.
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Originally Posted by monsterbaby
I don't use sewing pins, or other sharp objects to puncher the insulation, by doing this you are providing a place for moisture to get to the copper and begin corroding it,..............
Last edited by CowboyBilly9Mile; Aug 4, 2006 at 09:02 PM.
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Originally Posted by monsterbaby
I don't use sewing pins, or other sharp objects to puncher the insulation, by doing this you are providing a place for moisture to get to the copper and begin corroding it, within a short time you may end up with a electrical gremilin, and when you trace it down you will find the wire is broke right were you probed it. If your going to back probe that means at the connector alongside the wire, most of the connectors have a rubber piece around the wires that will reseal itself to some extent or can me moved out of the way.
jd
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From: Connecticut
I'd have to say that, if backprobing can be done by virtue of getting a probe inside a connector and making good contact with the wire end, then that's probably the preferred method. But in my experience with automotive electrical testing, it's not always possible to tap into a circuit at a chosen connector or location. More often, your options are limited.
I also have a Fluke meter and have the accessory sharp probes that Bob mentioned (I previously used large, straightened paper clips sharpened at one end and clips). I have no reservation about sticking the probes into wires pretty much anywhere I think is the best spot. I also do what Billy suggests (add a dab of clear silicone sealer to the puncture "hole") but I'm also overly **** when it comes to stuff like that.
I also have a Fluke meter and have the accessory sharp probes that Bob mentioned (I previously used large, straightened paper clips sharpened at one end and clips). I have no reservation about sticking the probes into wires pretty much anywhere I think is the best spot. I also do what Billy suggests (add a dab of clear silicone sealer to the puncture "hole") but I'm also overly **** when it comes to stuff like that.
Last edited by Rockledge; Aug 5, 2006 at 12:01 AM.
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From: Durham, NC
Here is the URL for Fluke's automotive test leads. Obviously, piercing wiring insulation is not a problem, or a company as reputable as Fluke would not
design/build test probes for doing it:
http://us.fluke.com/usen/products/Ac...keUnitedStates
design/build test probes for doing it:
http://us.fluke.com/usen/products/Ac...keUnitedStates
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From: iowa
Bob I am going to respectably disagree with you, they will do it because people want the probes and it makes them money to sell them. Maybe it's just the way I was trained, but I have seen teh end results from people even using the small probes from fluke, they can and do allow moisture into the wiring. The putting a dab of sealer on there is a good idea, and would most likely seal it 99% the time, but I just like the idea of not piercing the insulation at all.
Here is a little test for you take a piece of wire say 14 ga. cut a couple of 1ft pieces off, then pierce the middle one with the fluke, one with a needle don't seal them, but tie them up under your truck somewhere like maybe the rear bumper or something (am saying under the truck for max exposure to elements since this is a test too see what can happen) leave it there for a year and then strip the insulation off and see how much if any corrosion you have in the copper, I think it will amaze you.
Here is a little test for you take a piece of wire say 14 ga. cut a couple of 1ft pieces off, then pierce the middle one with the fluke, one with a needle don't seal them, but tie them up under your truck somewhere like maybe the rear bumper or something (am saying under the truck for max exposure to elements since this is a test too see what can happen) leave it there for a year and then strip the insulation off and see how much if any corrosion you have in the copper, I think it will amaze you.
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From: Durant, OK (SOSU)
I also apply silicone or the like to seal a hole I make in wires. Even those that will be inside where "supposedly" moisture can't get.
I'd rather be safe than sorry, not like I'm going to screw something up by sealing it. And it's hardly a waste of time by any stretch.
I'd rather be safe than sorry, not like I'm going to screw something up by sealing it. And it's hardly a waste of time by any stretch.
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I don't care what Fluke's advertising/sales says, I have seen too many wires with punctures to know better. I do ton's of trailer wiring. Pins are very small also, but they still tear the insulation.
Say, Bob Ayers, do you know there is a member on the Ranger Power Sports board that has the exact same cars as you do. Modle T, Galaxie, Ranger? Amazing coincidence. jd
Say, Bob Ayers, do you know there is a member on the Ranger Power Sports board that has the exact same cars as you do. Modle T, Galaxie, Ranger? Amazing coincidence.
jd
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From: Durham, NC
Rob, and Jim, check out this URL. I did some testing today, and it might be of interest to you, if you probe through insulation with the Fluke probe, or a straight pin, the hole in the insulation closes up, not allowing any leakage to the conductor:
http://bob-ayers.smugmug.com/gallery/1742406/1
http://bob-ayers.smugmug.com/gallery/1742406/1