professor229

I will try to keep this brief... 1971 240Z....looked at it to buy and owner was not home, but his wife said we were free to try to start it... not much luck.... in storage for 15 years etc... he had it running a few days earlier.. We shot some fresh gas in the carbs and it did not fire at all when the key was turned to engage the starter... just no fire... UNTIL you released the key from start, to run... then you would get a hit....

Picked up the car, and the owner had had it running that morning, and clicked the key without getting in and the car started up... running rich though, but running... he drove it on the trailer, we got it home three hours later, and pushed it down the ramps to the road... it would not start... seemed like no spark???

So pulled the cap and the low tension lead wire seemed "burned" and perhaps even in two pieces... so pulled the wire.... and tried to find a new one... (suggestions there welcome too!!) Wound up repairing the wire with a copper strand splice and checked it for continuity.... fine... no problem, so I reinstalled and tried to start the car.... nothing... same symptoms... no spark it seems..... pulled the plugs, and fuel on the plugs.... meaning, no spark...

Friend and former Ford mechanic/parts man stopped over... and helped... Pulled a plug wire, put a new plug on the end... grounded it and I turned the key.... as predicted.... no spark...

Test light came out... checked the ballast resistor and both sides lit as they should.... Test light on the coil... one side was very bright, other side noticeably dim....

Next, pulled the cap.... and with the test light checked the feed coming into the low tension wire.... turned on key..... bright light.... checked the other end of the low tension lead, where is goes to the points and turned the key to start and no spark to the points.... but wait!!!

When the key was turned to start.... no electricity to the points.... but, when the key is released from start to run, there is a short burst of light to the points side of the low tension lead... we confirmed this several times... turned the key to start, nothing on the points side... then, when releasing the key to run, every time, the test light flashed.... hmmmmmmm

Theories?

I have a couple... the Ford mechanic said that at one time, there were some Ford cars that had an adjustable switch in them.... could it be the 240Z has an adjustable switch? and if so.... tell me more...

Also, we had a rather large Kohler motor, that used a special coil... 12-14 volts when the key was clicked for a burst of electricity to the motor, but as soon as the key was allowed to return, the voltage on the coil dropped to 10 volts to prevent damage to the points....

There.... read the manual on troubleshooting, can't find an definitive answer there, and tried to find a section telling about the switch... nothing... so here I am....

Any help/ideas welcome... PS... As bad as this is, we had a good day in that at least we know generally why the motor won't run... now just to find the reason and fix it... Again... thanks...

Steve260Z74

Advice:
Go to the Xenon S30 reference page and download the 71 supplement and 72 FSM.

Technical explanation:
When the key in is the ON position, the ignition switch completes a circuit going through the ballast resistor to the coil. Since the coil is in series with the resistor, the voltage at the coil is dropped to about 9 VDC or so.
When the key is in the START position, the ignition switch completes a circuit that bypasses the ballast resistor, giving a full 12 VDC (or so) to the coil.
My guess is that the circuit to bypass the ballast resistor has been broken. When trying to start the car, the starter spins the motor, but there is no spark. When you let the key go to ON, the motor is still spinning due to intertia, but now you have voltage to the coil. That is what allows the car to start as you let off the key.

professor229

Steve....you have more/less confirmed what we thought... We did argue with it again today for a bit.... and at the coil and ballast resister. We followed the book to make sure that when the key was turned to start, that there was a strong electrical flow from the coil wire to ground. The first time we did it, we struggled to get any spark from the coil wire to ground... then I cleaned up the to connections ( plus and minus) to the coil.... and put new ends on that fit tighter as well.... Then we ran the coil wire to ground and this time we got decent spark... You know, I never thought about it, but we should have tried to start that car right then and there!!! We didn't.... GETTING OLD!!!

PS... to the positive side of the coil, is hooked a little circular device that is attached to the coil support bracket... is this a noise suppression unit or something and would it have anything to do with this car not starting?

PPS... Have you ever pulled a switch on the 240Z and it doesn't seem that tough to do... I think I would/might feel more comfortable starting there with cleaning up some connections..... If you were doing the diagnostics on your circuit idea, where would you begin?

Again... thanks for confirming what we were guessing as well....

Dennis

Steve260Z74

It is a condenser. You can take it off without it adversely affecting performance. It just might cause some noise in your radio.

From what I've read, to take off the switch, you'll need to get the ignition switch off of the steering column. That means cutting slots into screws since they had break-off heads. Common wisdom says to do that with a dremel until you can get a screwdriver on it.
I would do as you think and first clean up connectors. There can be corrosion within the crimped ends. Then pull the wire off of the coil and check voltage at the positive terminal of the coil while someone is holding the key in the START position. You should have about 12 volts at the coil. If you don't have voltage at the coil with the key in START, then move your testing to the ignition switch. Look for contintuity between the proper pins with the key in start. If the switch is good, it's in the wiring harness.

If you are desperate to get it running, you could run a hot wire from the battery to the coil for starting. I would put in a fuse, crimped connectors, or something into the circuit so you can break the circuit if you need to. Do NOT drive the car like that, though. It is for a short-time run only. You only put 12 VDC on the coil to start the car unless you have a coil with the proper impedence.

professor229

Wow..... last night I sat down dead tired from body work all day.. and read and read some more and then thinking about the couple of tests we did to try to figure it out... since the coil wire grounded yielded just about nothing, even with the terminals cleaned up and/or replaced, and we know the problem is not low tension, but high tension, the focus was on the switch... ebay... found "several" but I don't quite understand the spade connectors on it until I get a good look at the existing switch... and I think there are five... diagram??? which is which? they are sometimes labeled... and deduction will tell you a few of them and then the process of elimination should get to the one that should light up when the key is turned to start.... BUT, it looks like it is pointing at the switch.... I run a golf course, and some of our older equipment has this same problem as time goes by.... and, the switches look "similar"... the difference is, I have a complete manual and the switch is labeled anyway..... Again... this appears to be the next step.. but Jerry, my retired parts man, is going to take the Haynes manual over to a mechanic at the dealer where he works part time, and bend his ear... Betcha he comes back with... replace the switch.... Thanks again.. will post when I get one in, but with the Christmas rush now, that might not be until after new years....

Dennis

Steve260Z74

Dennis,
Would you do a compression test on the engine just by putting your finger over the spark plug hole? Probably not. Test the electrical system with a meter, doing as I described.
Also, put the Haynes manual aside. Use the factory documentation. Using the 71 supplement and 72 FSM will get you further than the Haynes. Keep your eye on eBay. The FSM for a 71 will pop up from time to time. It's worth the money to pick one up.
How can you tell about which contact is which? Use the wiring diagram as your guide. (See the attached picture.)
The white/red supplies the voltage to the switch.
The first row shows the contact positions for accessory. So you have the blue/red wire taking the voltage out of the switch.
The second row is Off. Notice that there are no lines or dots.
The third row is On. You have the blue/red wire in contact with the white/red again, and you have the black/white wire for the ignition.
The fourth row is Start. You have the green/white wire in contact with the white/red for the ignition. It bypasses the ballast resistor. You also have the black/yellow wire that goes to the starter.
When you take the cover off of the steering column, you'll see the wiring harness plugging into the switch. You can identify the wire colors and know what pin does what.

Color guide for wiring S30 wiring diagrams:
B - Black
W - White
Y - Yellow
G - Green
R - Red
L - Blue

By the way, you can get the replacement switch from Rockauto or Amazon. The Beck Arnley part number 2011174 will work. You can even get the full ignition key lock with new keys via Amazon if you want, especially if the tumblers in the ignition lock are worn to the point that the key comes out when the car is on.

professor229

Hi Steve.... again, thanks for the information and you anticipated all the questions I was going to ask but need clarification on one... is it the green/white wire in the fourth row that bypasses the ballast? I assume that is right.... and that is the circuit that I am 99% sure is not right.... now, whether it is in the switch, a broken wire along the way, or a badly corroded connection is debatable. I have a young mechanic reviewing the wiring diagram, theory, and what we will use as the next diagnostic test. Simply, either the coil is bad, or the switch is bad.... however, we know the low tension circuit works. So to test the high tension circuit, we will by pass the switch and hot wire the car. If it starts, the problem is narrowed down to a switch or broken wire.... If it does not start, we can assume that the coil is probably had a good life but seen better times. I did research switches and Rock Auto has the best prices, but, after shipping, it is a wash with O'Reillys. Advance and NAPA are a little high... I did take off the doors today (complete rebuild) and studied the area where the switch is. I have seen a lot worse. Hope that is it... As far as Haynes manuals etc... I know they are a little light in some areas for information, but this one is the English version and has 99% of the information I will need for this build.... Tomorrow, we may try to hot wire the car... and will let you know what happens... Thanks again for the wiring information... it is in the Haynes manual, BUT I would need to copy it and blow it up on a copier or buy a pretty good magnifying glass.... Dennis

Steve260Z74

Yes, the GW wire bypasses the ballast resistor.
You can test the wire easily by using an ohmmeter. You will need to use a long lead or attach a wire to one of the leads. Touch the leads together to get a baseline resistance. (This is very important to do if you attached a wire to the lead of the ohmmeter to get it to reach.)
Unplug the harness from the ignition switch. Attach one lead of the ohmmeter to the positive on the coil. Attach the other lead to the GW wire. You should have less than 1 ohm resistance. (Be sure to subtract your baseline value.)
By testing this way, you are testing the actual wire and not a surrogate. You can confirm with the hotwire. However, from what you described, I feel fairly confident that you will discover that the switch is the culprit.

professor229

Steve.... thanks again... I got another suggestion from the local young mechanic... he understood the whole concept after looking at the schematic diagram of the two circuits.... and said we didn't really need to hot wire... can if we wanted, but his suggestion was to run a hot wire from the battery to the positive side of the coil, skipping the ballast resister of course... The hook up a voltmeter on the negative side of the coil... if 12 volts, the coil is good and the switch is probably shot... or corroded; whatever... or if less than 12 volts or non existent voltage, the coil is bad.... I think you are right though... switch... simply because it started as an intermittent problem.... Think at that time I will dig in and take a look at the green white connection on the spade terminal... and go from there.... Only other thing that cross my mind was the possibility of a fuse between the switch on the GW wire before it gets to the coil??? Could it be that simple? Will check the fuse panel too.... just in case...Thanks again...

Steve260Z74

There is not a fuse between the GW and the coil.
You can also measure resistance on the coil to determine health. If it is very high, it's broken. If it's too low, it's shorted. I might take a reading myself on one out of the box to see what it is.

professor229

I still think it is going to be the switch or a connection........ but if that does check out, the coil is only about $11 locally for the 240.... Don't comprehend too well at night so I will read more about procedure to get to the switch... I have read it once or twice... Big snow storm tonight too so I will be moving some snow tomorrow too.... take care....

professor229

Hey... just wanted to run the probable solution by everyone and thanks for the help... Finished working on the floors today, and had a few extra minutes so looked at the wire again and common sense says to follow it back but since it is encased in an electrical tape wrap from around the coil area, it was one of those take it apart deals... so I unraveled several feet of old electrical tape and there it was... probably the solution... It is obvious that someone has cobbled this all in and did not have the correct schematic... so the wires are there, but in the wrong place for sure. Tomorrow, I will have my friend come over and we will run the switch but five will get you ten that the black unknown wire is the "run" wire that sends 12 volts on run to the ballast resistor... Why someone wired it in the loom all the way to the distributor, and then letting it hang there, is a real mystery.... Thanks for all your help!!! Dennis

professor229

I thought I had a handle on the starting problem, until I ran into a disconnected black wire in the harness near the distributor. Well, after downloading a simpler schematic to the car, and discovering a red black wire spliced into the wire from the negative side of the coil to the distributor, it prompted more research. In the diagram, it shows a black/red wire connection spliced in to the negative side of the coil to the distributor. Further, that black/red wire leads to a thermal relay that works off a temperature sensing switch on cars with automatic transmissions. My car does not have an automatic transmission, but, from the extra drive shaft I found and the fact that this car has a five speed, it is an obvious conclusion that the transmission was replaced. I will check tomorrow, but the manual shows where that loose black wire is supposed to be connected and I hope to find a spade terminal at that location to plug it in and in a perfect world the car should start. The manual does suggest manual does have a procedure for checking this device, and it involves manually "bridging the harness plug." However, I prefer to take this thermal relay completely out of the circuit. Has anybody had any experience with this relay or the changes required to swap a five speed into a car with an automatic? Any ideas appreciated.