I Recently purchased a 1973 240z, which had been stored for may years. After doing all the necessary things before I could fire her up ( runs strong buts need fine tuning) , it was on to electrical.

I had working

headlights

reverse lights

left signal

left brake ( heavy draw)

front parking lights ( right side dim and heavy draw)

left rear parking light

My marker lights have been removed?

I did not have working

right rear parking light

brake lights

licence plate light

dash lights

After cleaning every switch, socket and checking every wire from the front to the back the only thing I had found was when the front parking lights had been removed someone pluged the front right wires together. Unfortunately that only fixed the front parklights front signals and dash lights.( when the rear harnesses were un pluged) Thus confining the problem to the rear. I started re traceing the harness back over the wheel well, removed the expansion thank and pulled the speaker in right rear corner......at sometime someone had installed a drywall screw to attach the bottom right of the speaker, peircing through the wiring harness causing all my problems ( and yes I did the victory dance). Fixed the 2 damaged wires and every light on this car glows to perfections .....or as close as they can get until I buy my PLH and HLH from zs-ondabrain.

Moral........it is usually the things touched by man that go wrong, so look there first!

The only bonus of me starting at the wrong end is that the entire electrical system has all been cleaned, greased and inspected

If it weren't for all the excellent info within these posts, who knows how much longer this would have taken me.

Thanks to all those that don't even know they helped

This is a motivating post!

I find there are times when tinkering with / working on my '73 240z (Layla) it can be a morale / mood booster, or a frustration inducing mess.

I like to stick to the first one. Wiring is a facet of autos I haven't gotten skilled at. I might pick up a book on Amazon.

I know my bracket in the rear for the speaker was removed; I have speakers in the back panel now. And a 1980s antenna booster box mounted to the antenna.

Thanks for the tip.

The electrical systems in 40 year old cars is not that complicated. Most ever potential in the car is 12 VDC. A notable exception is the primary side of the coil when the car is running & has a ballast resistor. The chassis is negative in most cars, including our Z cars. Stock black wires are paths to ground/chassis. Wires are color coded in the wiring diagrams in the FSM.

You can buy a reasonably good multimeter for not too much money. Learn how to measure voltage and resistance, and you can trace most any circuit in the car and know how it's doing.

You can also post questions here to get you on the right path.