keep frying wire from starter

[DOHCD15]

.1971 240Z. the keys were not in the ignition. i wiggled the wire to the oil pressure sensor and then the wire that goes directly from the starter to the wire harness melted. i then noticed smoke coming from the back of the ammeter. once the wire to the harness melted i removed the battery, attached a jumper wire and then reattached the battery, imediatly that wire began to smoke. help, i am not knowledgeable at electronics, how may i find a ground. i do know how to use a multimeter and where the cable wire disconnects between the starter and ammeter. am very willing to learn

[70 Cam Guy]

If you fried your fused link, the wire from the starter into the thick wire harness, something has shorted to ground. I would no recommend using a jumper in place if there's a short.

If you were jiggling a wire, and the fusible link blew at the same time, I might start looking there. If insulation has melted or worn away and wires cross, this could be a source for your short.

I have used these sites for help with my car.

http://www.atlanticz.ca/zclub/techtips/

The electrical section has a tips link, which is actually pdf instructions for a multimeter.

If you really want to familiarize yourself with automotive testing, that may be a good place to start. You have a good project if you were seeing smoke under your dash. The burned wires will need to be identified and fixed. It may be a matter of identifying which wires are supposed to have voltage but have continuity to ground. White wire with a red stripe on our cars are power wires. If you get continuity to ground or zero resistance to ground, you know you need to take a close look at that section of wire

[Mikes Z car]

Is it possible that the fusible link is missing? Wouldn't the fusible link normally blow before making wires smoke?

[EScanlon]

The wire you mention going to the Oil Pressure switch may have NOT been for that purpose.

You may have been inadvertently connecting one of the + connections to the alternator directly to the oil pressure switch and thereby grounded the battery's + post via that wire. That would cause both the fusible link and other wires to melt.

Was that wire ALREADY connected to the oil pressure switch, or did you just see it loose and thereby connected it?

But, you definitely melted the Fusible Link, that IS what they're supposed to do when faced with a major short. You do NOT want to replace it with plain old wire... unless you want to burn up the car.

FWIW

E

[DOHCD15]

once i disconnect the link for the white wire under the glove box i should put one test lead to ground and another test lead to the end of the connect going to the starter. then i am supposed to read an overload of resistance if the wire is good, correct? if i read a low level of resistance then it means that i am completing the circut between the wire and vehicle body( ground) therefore causing the excessive current draw? so in the short and simple question, am i supposed to read overload in every point of the circut when the key is not in the ignition for every section of wire tested after it leaves the starter? and is the ammeter a resistor and if so, for it to still be good i would need to read some resistance across it's terminals? when i test the at the fuse box i should disconect the red and white wire and then test it to ground otherwise i would read the resistance across the fusebox because it is grounded??

[DOHCD15]

the oil pressure switch is a known good switch since it has been working flawlessly since i purchased the car, i didn't disconnect any wires or plugs, i merely jiggled the wire while it was still connected. if i grounded the + wire to the starter should't i have just popped a fuse first.

[EScanlon]

I'll let someone else decipher your prior post.

But in reply to your last one, if the wire you jiggled crossed or short circuited a circuit that isn't protected by a fuse specifically, it would probably cause the fusible link to blow if there is a MAJOR current draw because of the short.

Oil pressure switches are pretty much bullet proof, but they CAN go bad. Granted, it's a simple resistance switch and failure is an extreme possibility but by your statement, simply "jiggling" the wire connected to it shouldn't have had this major a result.

Before you go boning up on how to use a multimeter, use a plain old set of eyes to examine the wiring and connections.

If, as you describe, the car has been performing flawlessly, then you may have a problem that is easily detected by simple observation.

My 2¢

E

[70 Cam Guy]

I have to agree with E, use your eyes and maybe nose to look for anything apparent.

To answer your question about the meter, the resistance may not be overload but it should have some value. I'm honestly not sure how to test the ammeter for function. I imagine it will have a resistance as most components would.