No power to starter

[Drewfrazier]

I am having intermittent issues getting electrical power to the starter on my ‘72. I drove it this morning without issue but when I went back in to start it this afternoon, nothing worked, starter or headlights. Battery (new) is holding a charge of 12.79 v, there’s no clicking noise and the ammeter doesn’t jump when I turn the key. This happened only once before, but the ammeter showed a strong draw at the time, and the situation corrected itself. I am aware of no starter interrupt switch unless clutch is depressed or tranny is in neutral. Reading from the Unfused circuit on the Fuse Block to metal is -125 mV. Reading this over, it sounds like a faulty ground or a short circuit between battery post and ignition switch but that doesn’t explain the headlights out. As a side note, there is a trace of thin oil appearing under the ignition switch (also new, see attached). My question is, what should I check and in what order? Thanks, folks!

 

[HankScorpio]

If there is no power at the large battery cable where it attaches to the starter then there is likely corrosion inside the insulation on the battery cable. Check the battery cables closely, it can be difficult to see corrosion inside the wires under the insulation.

 

[6872xtc]

The oil seeping from the switch isn't a concern to me. At least the switch has some lubrication inside it.

You should be able to use a voltmeter across the battery terminals and battery cable ends. I start with the ground cable and terminal. If you put a test lead on each side of a connection, you should see 0 volts on a good connection.

As Hank said, corrosion can hide.

 

[ashman]

Also, check the fusable link wire. If your wiring is stock, it's a wire that runs from the battery (positive) and across the top of the radiator. It might also go to a junction on the fender, but I can't remember for sure at the moment. If that is corroded, you won't get power to anything.