Continuity Testing made easy.


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FNQ Australia
Disclaimer. I will not take responsibility for any one cutting of their finger, when eating a banana while using a power-tool and reading this article.

I understand the complexities of my brain trying to cope with learning to read an electrical wiring diagram and then applying them to the bike................... Why couldn't i.............. i could read building and piping plans!!!!...........I found visually they don't relate as a picture on the diagram to what i was looking at on the bike.

You need to learn to use a reasonably good Volt meter. Buy one with heavy duty testing leads, (quality testing leads are the single most important part of a tester, IMO).

NOTE; All good volt meters have a good basic instruction manual supplied. These are a must to read..........learn about your Meter.

Continuity testing.
Volt meter Turned on, set to 200 Ohms, (I'm set on 2K Ohm's. That will work),....the lower the setting the more resistance it will pick up and show on the meter ........Digital and analogue........Purpose of this test is to get all 0000 on the screen.
Analogue meter needle will shoot to the hard left. If it wavers more than a small bounce once, then resistance is detected, the further back to the right the needle moves, the more resistance found.
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Pic shows meters on and full resistance, (no continuity).
Resistance of any kind = less volts.
No resistance = Full continuity, (full power), supplied to the circuit
The more connectors there are in a circuit there is a chance they can cause a small loss of power, (some resistance). This is normal.

Test the meter for any resistance there may be in your leads......Any numbers should be written down for later reference.........In pic 1, i have a .000 resistance when i connect the probes together. I am Holding them firmly together, at a 90 degree angle, in the groove near the tips....................

In these pics I moved the probes around as i was shooting a burst, and as you can see Continuity changed, this can also be caused by some slight oxidizing on a part of the probe, or movement causing a bad contact. The probes have to be used properly or your final conclusion could be compromised.
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When the probes are held steady, (Pic 1), and the lowest no is steady on the screen, this number is then carried over to your continuity test Number, (when wire testing), and subtracted from any resistance number on the test screen............ If your probes read .002 and your final Test screen has .002 then your resistance is infinity, (full continuity) .............This is what your aiming for.........any number higher than your probe number, means you have resistance in the wiring circuit your testing.........The larger the number = more resistance = less continuity, means less power is getting through the circuit

I chose the Lg wire from the bucket to the Reserve lighting Unit for my test due to the wire being exposed beyond the plastic protector. ..........
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How the circuit is completed...........Red probe cannot touch any of the other wire colours in the connector
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All up this was a 20 shot burst from the first pic till last............(Had to connect probe and shoot the camera simultaneously)...........
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First pic. No contact. Full resistance, no continuity

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Second pic shows contact...........extremely high resistance, some continuity. If your circuit showed this it means there is a circuit but very little power is getting through........ Conclusion would be....Broken wires, some still connected or very bad corrosion around the connector area.

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Third Pic. If you get this reading the circuit is broken = Broken wire in the loom or at the connector. If wire is broken in the loom leave the meter connected and wiggle the loom or wire and pin point where the problem is

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Stabilized .002 and dropped to .001 just as i stopped shooting. ................This would be acceptable as a good circuit. the difference could be due to the connectors being dirty...............

Conclusion..Good continuity but the connectors are dirty and some wire is exposed. I thought the exposed wire might show some resistance, it had broken a couple of strands by the time i tested...........
Solution; Disassemble and clean connectors, replace connector where the wire is showing, make as new.

Test a circuit to a switch............. Then after the switch to its destination............ If both are good now do a full circuit including the switch. ...........doing this procedure, (excluding the switch first), pin points any problem area in the wire or connectors............... if resistance is found, when testing through the switch, then the switch needs to be disassembled, contacts cleaned and wiring checked for broken wires or bad soldering.............always retest after any cleaning of connectors/contacts, or fixing of any problems found.

You need to go through this process, one colour at a time. .............Indicator circuits are a good one to start..................Don't move around the loom, work on one circuit at a time. You will find out when you get to problem areas.

I found buy doing this and cleaning and retesting after a clean up my figure's improved. When power was finally supplied, the result through the indicators was very noticeable, the flashing was quick strong and regular, this was off a properly charged battery without the engine running.

By the time your finished you know your loom....... mark any differences found or changed for future reference

ome pics of before and after cleaning bullet connector with my Dremel drill with a small ball bit. This was an old loom i cleaned up.
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Dang Skull - bloody well done! It's almost like you're a toaster (EE). ;)

This is a very useful document for newbies. As you say:
  • Get a decent meter;
  • Sit down with a coffee and your meter and your wiring harness (loom);
  • Work your way through Skull's post;
  • ....and when you're done, you will know a HECK of a lot more about electrical systems than you did before - and likely a lot more than most other people.
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I had an inspection job random testing mobile homes for electrical quality problems, after they had passed the government required tests. I used a $10 Walmart Ohm meter. I could find problems that could not be found by using AC power connected to the home. If a manufacturing problem was suspected I could dream up tests to check for these errors. I was the most hated person in the plant, they hated my ohm meter just as much, but I saved the owner many dollars in service calls after these homes were delivered. I shouldn't comment any more about the quality of those homes.

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As much about what i got from the camera doing this, as it was about putting it together. In the last 6 frames they are only a part of 20 continuous shot burst 18-55mm lens set on 18mm, F-stop/35, 1/25 second shutter speed, iso 3200.
Fairly new to me Cannon 550D. Has factory lenses, adequate but the budget set.