Series 1 Ignition Switch Problem

[EarlyZed]

I have a series 1 (8/70) with some starting problems. The start position does not provide any spark! The starter motor is healthy, but the car will not start until I drop the key back to the run position. A couple attempts and it zooms to life.

I have tried a second ignition switch (junkyard replacement) to no avail.

It's possible both switches are bad. Does anyone have a reliable test method for these? I ran the switches through their positions and got the following closed circuits.

Switch 1)

ACC: WR LR

__ __ __

RUN: WR LR

__ BW __

START: WR __

BY BW GW

Switch 2)

ACC: WR LR

__ __ __

RUN: WR LR

__ BW __

START: WR __

BY __ GW

Everything made sense; switch 2 was missing BW on START! Funny thing though, the symptoms didn't change. Neither switch will fire the car in the START position.

Is this a proper test for the switches? Can someone confirm which line runs 12v to the coil? Is this line fused? Is there another component in the line that might be causing this grief?

I'm at a bit of a loss as to my next diagnosis step. Any suggestions would be appreciated.

Thanks,

Randy

[Arne]

So are you saying that in the start position that it cranks, but won't catch until you release the key? If so, there may be something wrong with the wiring to the coil. In the Run position, the switch sends power through the ballast resistor to the coil. In Start, power is sent through a different wire directly to the coil.

[EarlyZed]

Yes. It only catches when the key is released.

I reviewed my wiring diagram and I messed up a bit on my original post. Switch 2 looks good. Switch 1 has contact on BW which doesn't match the wiring diagram for the START position.

I am using the Haynes wiring diagram. The diagram shows the Run and Start circuits recombining before being routed through the tach. Does it make sense that I have a problem on the start circuit before this join? (BW wire)

[Arne]

Yes, it sounds like a problem between the switch and where the to coil feeds join on the coil feed in the Start position..

[geezer]

See if this is a different diagram than you have.

[geezer]

Here's another you will have to piece together. Hope they help.

[EScanlon]

The SECOND switch has the proper connections in all three positions.

The First switch has an extra and not correct connection with the BW wire in the Start mode.

Your assesment that the wiring goes through the tachometer before it gets to the coil is correct, and you've apparently picked up on the extra BW contact.

Arne's description has it correct except that it omits the tachometer. Unless something has been disconnected or removed, both the Tach and the Resistor are required to have the engine start and run.

(Note on edit: you CAN remove the resistor and tach both, you just need to properly connect the removed wires to finish the proper circuits.)

Power to the coil starts with the W/R wire coming into the ignition switch. In the START position, the power is connected to the BY wire to energize the starter solenoid and also to the GW wire which then connects directly to the Tachometer. At the tachometer the return path for the power then exits via the BW wire which is then connected to the positive post on the coil.

In the RUN position, power from the ignition switch goes to the BW wire which connects directly to the Ballast Resistor in the engine bay THEN it goes to the Tach via a GW wire and finally to the coil via the BW wire previously mentioned. This seemingly "recombined" circuitry is a simple bypass circuit. Your assesment was right, except that you had the power flow going backwards.

Note that there are TWO BW wires. One connects to the resistor and one connects to the + post of the coil. The GW connects to the resistor.

That you're not Starting, but you it does RUN, tells me that the Ballast Resistor is disconnected and now you have the BW wire going to the resistor mounted directly to the coil's + post. This being the case, I'll bet that your tach isn't working either.

FWIW

Enrique

[EarlyZed]

I'm starting to understand it all.

I'm thinking both switches might be good. Geezers file Lastscan.jpg looks to show the BW connecting in the start mode. The genesis of this switch is a little shaky. I was originally thinking my switch was bad and went to a locksmith to get a key cut for a later model lock/switch combo and he pulled an old lock with switch out from the parts bin in the basement. Someone had labeled it Mazda but he swore it was an early Datsun set. It is oh so close but not quite. The lock fits a steering column perhaps 1/8 inch larger than the Z’s. The switch is physically interchangeable. This raises an interesting idea, if indeed it did come from a Mazda, might old Mazda ignition switches be available to fit a Z?

I will go with Switch 2 and start tracing/testing my wires. I’m not sure if I can get an evening in the garage this week so I may not be able to do much until Saturday.

This car has been a work in progress. New floorboards, paint and interior were finished late last year. Starting and rough running problems vexed me so I took it to a mechanic who diagnosed a few issues, not least of which was a worn distributor that would spin in and out of true. He installed a Mallory electronic distributor and as I understand things, bypassed the ballast resistor with a jumper wire. He also diagnosed my START problem as the ignition switch.

The tach does work.

Thanks everyone for the guidance! I'll keep you posted.

[geezer]

Someone will probably clarify this for you, but I remember reading something about the slight difference in the early switches and what was done to make it fit. Also I came across an NOS early switch listed on Ebay only yesterday, but did not put it on my Watch List. If I see it again I'll put up a link.

[EarlyZed]

The switch!

I walked all the circuits and they tested fine. I tested the switch in-situ with some jumpers and sure enough, it was bad. Using my replacement switch it went vroom on the first try! So with much embarrassment I have to admit I messed up in my original post; I must have tested the same switch twice! (They sort of looked alike until I got out the paint stick and labeled them!!!)

Thinking forward to the day when my junkyard switch fails, I took a handful of parts along with me to a machinist I know. He figures he could put together an adapter to fit between the Series 1 lock (1 1/8" diameter) and the later ignition switch (1 3/8" diameter). You could then buy an ignition switch to fit your original ignition lock rather than the ignition and lock. He wasn't too interested in spending the time to AutoCAD the design to spin 1 out, but figured if he did 10 or so he could save on his set-up time and do them for about $50-$60 each. If there is enough interest he said he'd run one up for me to ensure it will fit. Might anyone have an interest in such an adapter?