Help me with this electrical problem...

woodlandfarms · Jul 27, 2015

I could run a long list of issues with my PT and electrical. Seems like you got yours fixed and not an uncommon issue (PT should have a better wiring system, it would not cost them a penny more). Grounds are my biggest issue, part of my yearly mantenance it to pull and clean as much as many as possible.

I had a weird one this spring. My guages were all over the place, temperature was running low then high, then low, voltage same. Knew it was electrical but not sure how. Eventually left the engine tub and went to the guages and switches. Found that the clamp that holds the main guage cluster had cracked (I think a branch hit the guage and caused the plastic to crack) anyway, it was not grounding correctly. Ran a heavy ground from the engine to the front tub and then up directly to the guage. Now no problems.

marrt · Jul 27, 2015

k0ua said:
To troubleshoot these types of problems. Place negative lead on battery post. Measure with positive lead along circuit path. You would have found the voltage drop across the fuse holder quickly by measuring one side and then the other side and noting the voltage drop with a load placed on the circuit.

What do you mean "place negative lead on battery post"? You're talking about the multimeter lead, correct? Also, in your example, I assume you'd want the circuit under load? Just trying to visualize your troubleshooting procedure since it seems like a way to use voltage, instead of current, to get a better sense of what's going on.

k0ua · Jul 27, 2015

marrt said:
What do you mean "place negative lead on battery post"? You're talking about the multimeter lead, correct? Also, in your example, I assume you'd want the circuit under load? Just trying to visualize your troubleshooting procedure since it seems like a way to use voltage, instead of current, to get a better sense of what's going on.

Yes and yes . look for the voltage drop. As in the example of the high resistance connection. There will be a voltage drop across it. Ask yourself the question should I have a voltage drop across a fuse? No of course not at least not much of one, so if you measure a large voltage drop across a component like a fuse or piece of wire or a battery clamp connection etc. Then investigation why this component under test and under load exhibits this unusual behavior. The answer is this component under test and under load is exhibiting a high resistance.

marrt · Jul 27, 2015

Got it. I was aware of the "risks" of using voltage to test the integrity of a circuit. But your approach offers a good work around that will come in handy. Thanks.

BobRip · Jul 27, 2015

I had that fuse holder become erratic. They use insulation displacement connections inside the fuse holder, A very bad design.

k0ua · Jul 27, 2015

BobRip said:
I had that fuse holder become erratic. They use insulation displacement connections inside the fuse holder, A very bad design.

It is for anything that needs to pass much current. we use them all the time in the telecom industry, but typical loop currents are about 20 to 25 milliamps. Not much. Also telecom wire is solid wire. Insulation displacement does not work worth spit with stranded wire.

BobRip · Jul 28, 2015

I think telecom has a low vibration environment. Power Trac is not.

k0ua · Jul 29, 2015

BobRip said:
I think telecom has a low vibration environment. Power Trac is not.

good, point. But in any case, Insulation displacement connectors are not the greatest for your automotive uses.. Yes people use them, and cuss them sometimes too.

BobRip · Jul 29, 2015

Exactly. I did not know about solid better than stranded. I fixed a neighbor's camping trailer just last month with these. They are just not quite good enough for this.