Intermittent ignition help

Datsun78 said
'69 Barracuda convertible, 318, auto trans, Pertronix ignition module. Have intermittent problem where car won't start. Have lights, horn, etc, but no click or starter engagement. Shifting trans, repeating turning key, tightened positive battery cable has no effect. If left for a few days or weeks, will start up and run fine, until happens again. Replaced neutral safety switch and connector, but no change. No discernible pattern to issue, other than has always happened in the garage(fortunately).

Any guidance to what to check?

Thanks!

Mark

Go over to MyMopar and download a free service manual. You may have to settle for Dodge vs Plymouth. I realize it may not have "rally" cluster wiring included. Also go to their wiring section and get the 2 page aftermarket diagrams. For some reason these are now zipped, often into a big package of several

You need a meter, test lamp, and some alligator jumpers if you don't have

Pull the dark wire coming off the starter relay which goes down the firewall to the transmission safety switch. Clip your meter, on DC volts to the now bare starter relay post (from which you just removed the wire) and ground the other probe. Twist key you should have voltage. If so, ground the post to which you connected the meter, make SURE the trans in in P or N and see if it cranks.

If not and if you had voltage to the meter in the first test, the relay may still be defective. With the NSS post still grounded pull the other flag terminal off--yellow goes to key "start" signal, jumper power from the "big stud" on the relay to that post. It should crank. If not

jumper directly from the "big bare stud" to the other "big square and bare" post and it should crank. if not you have a problem at starter/ starter wireing, bad wire from starter relay "square post" to the starter, or possibly a battery cable problem