Continuity Testing

[ronskydivepops]

Hey all. Can anyone explain exactly how to use a ohm/volt meter to check for continuity. Level 101 with pictures would really help. I profess I am an idiot when it comes to electrical procedures.

[GTJIM]

Just a slick way of saying that there is a path for the electricity to flow through.
If you put the meter on Ohms and place one probe at the end of the wire/circuit to be tested and the other probe at the other end - then, if the ohm (resistance) reading is very low (usually the left-hand end of the scale is 'zero') then there is a continuous path for the electricity to flow along between the places you have tested.
Can also be done by simply using a 12volt light bulb and torch battery connected between probes - light goes on = continuous circuit!

[jordan]

You use the VOM on continuity (omega) "Ω" and then put either "+' or "-" to ground, it doesn't matter which one and then the other one goes to what you suspect is continious or are testing to see if it continious, if it gives a reading of 1.00 then there would be continuity(depending on what scale you are on like 100k 100k 10000k for example.) This method is testing for straight continuity, to test resistance you would do the same thing but the reading would vary less than 1.00.

[tomking]

You the VOM on continuity (omega) "Ω" and then put either "+' or "-" to ground, it doesn't matter which one and then the other one to what you suspect is hot or are testing to see if it hot, if it gives a reading of 1.00 then there would be continuity(depending on what scale you are on like 100k 100k 10000k for example.) This method is testing for straight continuity, to test resistance you would do the same thing but the reading would vary less than 1.00.
__________________
If you do that while the circuit is HOT, you will blow out the VOM!! You dont test continuity while the circuit is hot or powered up.

[namba209]

Originally Posted by ronskydivepops Hey all. Can anyone explain exactly how to use a ohm/volt meter to check for continuity. Level 101 with pictures would really help. I profess I am an idiot when it comes to electrical procedures.

Here you go, I've got a jumper wire with alligator clips on both ends that I'm ohming out with two of my RadShak VOMs. One is in the OHM mode, the other has a signal setting that sounds off when continuity is detected. You can see that both are indicating very low resistance, indicating the possibility for good current flow. Also note both have a 20 amp connection for checking out hi amp circuits. Without that connection you could smoke a VOM in a high amp circuit. Also it has settings for AC and DC along with milliamp and microamp settings. HTH.

[ronskydivepops]

Thanks for the quick lessons everyone. Now to buy a meter that actually works. In the meantime I've noticed a few things. I replaced my original alternator with a GM 65 amp. At idle it only puts out about 11 amps. When I rev the engine it jumps up to 13. When I hit the horn it doesn't work until I rev the engine. Switch the headlights to high beam and they won't switch back to low unless I rev the engine. Also notice when I use the turn signals, the needles on my gauges move in sequence with the turn signals. If I hit the brakes the same thing happens, I notice the lights dim a bit and the gauges all move downward a bit. Took it for a spin yesterday afternoon and I couldn't duplicate the problem I've been having with the fuse blowing. Fritz the gremlin in my car threw a new twist at me. As I was pulling in the driveway I noticed the light on the alternator gauge came on dimly and was showing a slight discharge. Went to restart the car and the alternator light is not on when I first turn the key. Engine started, only cause I still have power in the battery. Gave up for the night. Don't really want to go thru the hassle of tracing down each wire for a short-but guess I'll have to, might be easier in the long run to just redo the whole damn wiring in the car. I did notice about a year ago that 1 ground wire in my left front lower driving light was actually shorting out that circuit when I tried to use it. Ended up running a new ground and that fixed the problem. BUT-I never did find where the ground was shorting. More later when I get the meter. Thanks again Ron

[Bill Hoffmann]

The first rule of using an ohmmeter is to make sure there is no power in the circuit! Disconnect the battery's negative terminal before doing any continuity test.

An ohmmeter measures electrical resistance, and unless it has an autoranging function, you need to select the range for the resistance you expect to measure. If you want to measure something like a wire or verify ground, you would use a low range, like 0 to 10 ohms. If, for the same purpose, you pick a high range, like 10 megohms, you may get false results, because it can measure things like the path across your skin. On the other hand, if you want to make sure you [I]don't[I] have a short circuit, you should use a high range and get an infinite (or very high) reading. For measuring continuity, it's nice to have a meter that beeps when you have a complete circuit.

[bq97]

Originally Posted by ronskydivepops Thanks for the quick lessons everyone. Now to buy a meter that actually works. In the meantime I've noticed a few things. I replaced my original alternator with a GM 65 amp. At idle it only puts out about 11 amps. When I rev the engine it jumps up to 13. :

The amperage rating is the maximum the alternator can deliver so the actual output will range from 0 amps up to 65 amps depending on the electrical load and the input shaft's RPMs. You will never get full output capacity at idle. With every alternator, new or rebuilt, there should be a test card included with the warranty paperwork. On the test card there is a chart or graph that shows the output in amps for a range of input shaft RPMs.

Next time you are at an auto parts store compare the test chart from two different manufacturers but for the same application. You most likely see a difference between the two when the alternator starts delivering and how soon it will reach maximum output. This is especially true if you compare an inexpensive rebuild to a more expensive rebuild. The better choice is a higher output level at a slower RPM. That’s one reason some people still experience headlight dimming at idle even after they have upgraded the alternator to a higher output capacity.

hth

[ronskydivepops]

[QUOTE=bq97;103295]The amperage rating is the maximum the alternator can deliver so the actual output will range from 0 amps up to 65 amps depending on the electrical load and the input shaft's RPMs. You will never get full output capacity at idle. With every alternator, new or rebuilt, there should be a test card included with the warranty paperwork. On the test card there is a chart or graph that shows the output in amps for a range of input shaft RPMs.

I don't remember a test card in the box. So I'm hoping I'm okay with the alternator I have. Now if I can just straighten out the wiring issues. The flutuation in the gauges bothers me now. I always thought it was probably normal-given the age of the car.

[namba209]

Originally Posted by ronskydivepops The flutuation in the gauges bothers me now. I always thought it was probably normal-given the age of the car.

O.K. Ron, which gages, and do they fluctuate in unison? If they do, it's probably a loose or dirty ground wire at the fuse panel hold down stud. If not, it could be nothing more than a loose or corroded spade lug either at the gage or the sending unit. HTH.

[ronskydivepops]

]

Originally Posted by namba209 O.K. Ron, which gages, and do they fluctuate in unison? If they do, it's probably a loose or dirty ground wire at the fuse panel hold down stud. If not, it could be nothing more than a loose or corroded spade lug either at the gage or the sending unit. HTH.

They move in unison. Not much, maybe a 1/16 of an inch. If it's just a ground I'll be amazed. I've cleaned and tightened every ground I could find and still have electrical issues. I think I may be better redoing the whole system eventually, or at least get a new and modern fuse panel of some sort, with blade fuses.

[namba209]

Alrighty there now there then. That could narrow it down some. The gages get power from the 3rd fuse in the group of 4, farthest from the 4 studs in the fuse panel. Then to instrument panel via black connector pin 1, Black/Red wire. From the connector, to a terminal block between the speedo and oil press/amp gage, then to each of the gages. The grounds don't really come in to play in this scenario because the gages use a separate ground or no ground to function. I would suggest checking the fuse connections, spade lug connection, insturment panel connector, and the terminal block for your problem. HTH.

[ronskydivepops]

Thanks Ron. Just what I wanted was more wires to mess with. Only kidding. Feel like I'm talking to myself since we have the same first name. I'll get right on it unless the hurricane takes my GT away. Thanks again Ron

[namba209]

Yeah, I felt the same way when I first responded to this thread. Anyway check the fuse holder first thing. There's not much holding the fuse in place and vibes could get it to make/break in a cyclic or random manner. You'd be amazed how a little play in the holder or corrosion on the bullet ends of the fuse create havoc. Keep dry and warm down there, if you aren't o.k. the GT won't be either.