How to troubleshoot my oil temp gauge/ground problem

Discussion in 'Electrical' started by Dr. Dolittle, Feb 27, 2009.

  1. Dr. Dolittle

    Dr. Dolittle Experienced Member Staff Member Moderator Contributor

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    OK - earlier thread about my oil temp gauge being erratic led the vast majority of you to suspect a grounding problem - that's why I'm posting this in the Electrical section.

    I'm totally brain dead when it comes to troubleshooting electrical problems. My problem is so basic I couldn't even find any tips in the Self Help Tips section.

    I found a very basic Sperry brand multimeter in my toolbox with markings for OHM, ACV, DCA, B.TEST, and DCV and the red and black probes coming out of the front.

    When you're all done laughing, can you point me in the right direction as far as using this thing to track down my gauge problem? Do I need a different instrument/tool? Does the bike's ignition have to be on or is this multimeter self powered? In other words does it send out its own current to test the continuity of the circuit being tested? What indications am I looking for, good and bad? Hard to believe my Dad was an electrician - he simply never shared any of his knowledge with me and I was too young and stupid to ask. :(

    Thanks, everyone.
     
  2. M' one.

    M' one. Active Member

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    A quick continuity test will tell you if the electrical circuit is intact. The meter should have an internal battery to power the meter itself . All you have to do to test if there is a good Gnd to the gauge is set your meter to the OHM setting, take a rough guess to what OHM range is required ( that is if the meter has different ranges ), connect one of the probes to the +ve input of the gauge and then connect the other to an other Gnd point on the bike, away from the gauge. If the needle on your meter indicates any value then your gauge has a Gnd , if there is zero movement then there is no Gnd. Thats a quick and simplified test, without knowing the correct resistance values its hard to take the test any futher. Beware your fault may be intermittent and that makes it a difficult fault to find. You do'nt need a power supply on to the gauge to carry out this test.
     
  3. Dr. Dolittle

    Dr. Dolittle Experienced Member Staff Member Moderator Contributor

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    Thanks M' one. Unfortunately, I do have an intermittent problem but this will be a good starting point.
     
  4. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Look around and see if you can find the instructions that came with that multimeter, or hit the internet and google the make and model and see it you can download some.

    Very simply, here is what all those letters are:

    OHM: just that. You are testing the resistance between the two points you touch with the red and black probes. If you touch them together, you will get "0" - no resistance. If you touch two other points and the needle (or is it digital?) goes to "the infinity symbol", you have infinite resistance, or an open circuit (like no ground!).

    ACV: this is AC (alternating current) volts. You can use this to check how many AC volts your alternator is putting out.

    DCA: this is DC (direct current) amperage. Be carefull with this. A normal multimeter can only measure milliamps (so don't try across your battery terminals on this setting).

    B. Test: I am guessing, but probably "battery test". This may be the condition of the internal battery needed to check for "ohms".

    DCV: DC (same as above) volts. You can use this to check how many volts your battery is putting out. Remember, it is polar so if the needle goes the wrong way, switch where the red and black leads are touching on the battery or whatever.

    See here to test your charging system (I know you are looking for a good ground on your oil pressure sending unit, but this will let you practice with your multimeter):

    Testing The Charging System - Harley Davidson Community

    TQ
     
  5. M' one.

    M' one. Active Member

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    I suppose it depends on the meter your using, in all of mine the needle moves to the zero when you have good continuity, ie: a closed circuit. If the circuit is broken the needle dos'nt move.
     
  6. Dr. Dolittle

    Dr. Dolittle Experienced Member Staff Member Moderator Contributor

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    Might have to find a different way to practice with the meter - that might as well have been written in Chinese as much as I understood it!
     
  7. M' one.

    M' one. Active Member

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    Doc, if you can operate an FMC, you can easily carry out the continuity test:D:D.
     
  8. STEVE07

    STEVE07 Well-Known Member Staff Member Super Moderators

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    Grab an old fashioned 12v. test light and put the alligator clip to a powered connection and use the probe end to test your grounds,If it lights up you have a ground.
     
  9. glider

    glider Veteran Member

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    Make sure when doing the above that the clip is on the POS terminal, not ground.:D

    You use a POS feed when testing for ground and a ground when testing for Battery with the test light.
     
  10. STEVE07

    STEVE07 Well-Known Member Staff Member Super Moderators

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    I didn't think I had to add that!:newsmile100: