Ingition switch wiring... (1 Viewer)

[Maestro]

I've been working on getting the old 40 back up and running. I have another thread detailing a bit of trouble with my stuck steering wheel. I haven't updated that thread because I'm trying to get the truck running so I can drive it down to a buddy to help get the steering wheel unstuck.

Onto today's problem, the darn thing just won't start. I rebuilt the carb many weeks ago. It fired up perfectly, first try, only to find a fuel leak I wasn't confident in fixing myself. Sent the carb (quadrajet on 350 swap) to get repaired and it got tested thoroughly before I got it back. Today I tried to figure out the problem and found a few issues. First, the wire leading into the coil is fried, it arced into the distributor. But looking closely, it doesn't appear to be damaged, other than the melted jacket. I haven't tested it for continuity yet, but I will. I've insulated it and will give it another try, at least just to try it before I buy a new coil. But this brings me to my next problem. I put a multimeter on the 12v input into the distributor. I swear I got 12v with the key in the start position one time today. Saw it with my own eyes, swear it happened. Now, I can't replicate it. Now I get nothing with the key in start position, and less than 1v during cranking.

I have a toggle switch start, so I am not using the starter pole on the ignition switch. On my truck, the distributor is wired to the accessory pole on the ignition. I put the key in the accessory position and hit the toggle switch to start it. In my limited knowledge with every car I've owned, the accessory pole gets very little to no power during cranking, which is why the radio and other accessories stop working when the engine cranks. But since my truck keeps the key in the accessory position, I suppose this doesn't apply.

Now, bypassing the fried wire on my coil, I have tested the 12v lead. Like I said, I swear I saw 12v today, but can't replicate it. What I see now is basically less than 1v when cranking and nothing when the key is on. I have no visible spark and I'm not about to lick my fingers and stand in a puddle. This 40 has always been finicky to start. If the battery isn't fully charged, it needs to be jumped, even with a new battery. But it did start first try after I rebuilt the carb. So now I'm trying to figure out which poles I need to be using, how to test with a multimeter and also figure out why it started right up after the rebuild but it won't now.

Can anyone shed a little light on how I should be wiring or testing my ignition? if I am starting in the accessory key position, how do I test voltage and troubleshoot this? Any help is appreciated.

 

[ToyotaMatt]

- Replace Your Glass tube Fuse or Fuses

- Don't Bother testing a 10 cent part like this

- I have had in the past several FJ's Glass Tube Fuses start and stop working or have a " Intermittent " working Non working issue

This happens because the thin TIN fuse element inside becomes detached from the inner part of the Chrome end cap where U

cant see it , sometimes I was able to twist off the chrome end cap after pulling the fuse out of the fuse box

I can only Speculate that Ambient temperature & or Vibration has caused this , and Temperature Heat buildup at a point of high

resistance ( The detached Fuse element ) causes it to stop and start working Intermittently

 

[ToyotaMatt]

I've been working on getting the old 40 back up and running. I have another thread detailing a bit of trouble with my stuck steering wheel. I haven't updated that thread because I'm trying to get the truck running so I can drive it down to a buddy to help get the steering wheel unstuck.

Onto today's problem, the darn thing just won't start. I rebuilt the carb many weeks ago. It fired up perfectly, first try, only to find a fuel leak I wasn't confident in fixing myself. Sent the carb (quadrajet on 350 swap) to get repaired and it got tested thoroughly before I got it back. Today I tried to figure out the problem and found a few issues. First, the wire leading into the coil is fried, it arced into the distributor. But looking closely, it doesn't appear to be damaged, other than the melted jacket. I haven't tested it for continuity yet, but I will. I've insulated it and will give it another try, at least just to try it before I buy a new coil. But this brings me to my next problem. I put a multimeter on the 12v input into the distributor. I swear I got 12v with the key in the start position one time today. Saw it with my own eyes, swear it happened. Now, I can't replicate it. Now I get nothing with the key in start position, and less than 1v during cranking.

I have a toggle switch start, so I am not using the starter pole on the ignition switch. On my truck, the distributor is wired to the accessory pole on the ignition. I put the key in the accessory position and hit the toggle switch to start it. In my limited knowledge with every car I've owned, the accessory pole gets very little to no power during cranking, which is why the radio and other accessories stop working when the engine cranks. But since my truck keeps the key in the accessory position, I suppose this doesn't apply.

Now, bypassing the fried wire on my coil, I have tested the 12v lead. Like I said, I swear I saw 12v today, but can't replicate it. What I see now is basically less than 1v when cranking and nothing when the key is on. I have no visible spark and I'm not about to lick my fingers and stand in a puddle. This 40 has always been finicky to start. If the battery isn't fully charged, it needs to be jumped, even with a new battery. But it did start first try after I rebuilt the carb. So now I'm trying to figure out which poles I need to be using, how to test with a multimeter and also figure out why it started right up after the rebuild but it won't now.

Can anyone shed a little light on how I should be wiring or testing my ignition? if I am starting in the accessory key position, how do I test voltage and troubleshoot this? Any help is appreciated.

.

 

[Maestro]

I did test all my fuses for continuity, and they all passed. The only one I was considering as being part of the problem was the "engine" fuse, although I don't really know what it is really connected to on my truck. My electrical is an absolute disaster from the previous owner. Maybe you're right that my fuse is causing intermittent problems, but I will need to verify that my leads are even fused before I blame that. I can try bypassing the fuse to see if I am getting voltage loss there.

 

[Maestro]

If it's not the fuses, and it's just the wiring, what are my diagnostics to test the electrical? Should I be getting 12v to my switched circuit on my distributor during cranking? Just to reiterate, my key only turns to the accessory position and starts with a toggle switch from this position. I need to know how to diagnose a no start issue, but I don't know what voltage is supposed to be going to the distributor during cranking. If I'm not getting 12v, do I have a problem? If I turn my key to the start position, I do get 12v on the starter pole, but I have nothing connected there, everything is wired to run on the accessory position. While my key is in the starter position, I get less than 1v on the accessory pole, which is what I assumed to be my problem.

 

[Maestro]

I know I definitely don't know what I'm doing. All I know is I'm not getting a spark. I put a screw in a spark plug boot and tried to spark it to ground while cranking and I get nothing. I am calling it a night for now, but I will try again tomorrow. Hopefully someone can see through my ignorance and maybe figure out what I'm doing wrong! Catch y'all tomorrow!

 

[ToyotaMatt]

- Post some Spec's or facts about your truck like the Year , what engine U have , are U running a OEM Toyota stock set up or

Aftermarket Upgrade one Etc.....

- Post some pics also of Your Ignition set up & the whole toggle switch bypass thing U have going on

 

[Maestro]

I spent some time collecting data today. In my original post, I did mention it has a SBC 350. Anyway, here's all the info I have tonight.
The vehicle is a 1966 FJ40 with a SBC 350 and HEI distributor. But all my trouble seems to point toward the ignition switch. The ignition switch is the original Toyota. The way this thing was wired up worked fine before, but all of a sudden it won't run now.

The current wiring from the ignition switch is:
1) Batt to battery
2) IG to distributor
3) ACC through toggle switch, then to starter
4) ST has nothing connected because you never turn the key to the start position. The key goes to ACC or "on" and you hit the toggle switch to start

With the key in the on position, I do have 12v going to my starter from the accessory pole and it cranks fine. But the ignition pole on the switch only has about 0.1v with the key on. When it cranks, the voltage goes up to about 0.5v. I am 99% sure the above details is how it was wired when it ran. i suppose I could have gotten confused and accidentally taken wires off and forgotten where they were, but I really don't think so. The only explanations I can come up with is that the starter and the distributor were both wired to the ACC pole of the switch and I took the toggle switch lead off and forgot where it was. Or, the ignition switch was working fine a month ago and has since stopped.

So, I guess the question here is... Should my ignition switch have 12v on both the accessory and ignition poles when the key is in the on position?

 

[Maestro]

I need to add my latest finding. Unless this is an intermittent problem and it was just coincidental, I got a 12v reading twice on my ignition pole with the 12v lead disconnected from the distributor. I also tested twice with the 12v connected to the distributor, and both times it reads zero volts. Could a bad coil turn 12v into 0v all the way up the circuit at the ignition switch?

 

[Maestro]

Okay, I have isolated the problem. I wired up my distributor to the accessory pole on the ignition switch, where I knew I had a good 12v. It started up and ran perfectly. I used the same wire that normally goes to the distributor, so that wire is not the problem. It appears the only thing left it could be is the ignition switch. So I have a temporary fix that at least gets it running. Now I need to look around to see how to either repair or replace my ignition switch. Thanks for at least trying to help Ragingmatt. If you have any recommendations for repairing the ignition switch, I'm all ears. I really want to keep it original as opposed to going aftermarket.

 

[Solace in Solitude]

I’d place a “wanted” ad in classifieds and find a usable ignition switch.

Perhaps @Living in the Past can tell you what years’ ignition switch will keep your ‘66 as original as possible.

If you had fried insulation on a wire from the coil, you really need to be sure you don’t have a short somewhere.

 

[Maestro]

I just checked SOR to see if they are available, and they do have a bunch of options at reasonable prices. I suppose if I could open this one up, the problem may be obvious, but I haven't gotten that far yet. I'm hoping I could possibly just put my cylinder in a new housing so I could keep my original key working, but I'll read up on that.

As for the fried wire, here is a pic below. It looks like it could have been mechanically damaged by the plastic keeper just enough to let it arc, but I don't know. One thing I have been reading up on is that leaving the key on with power to the coil can fry the coil. My ignition wire did have a momentary switch in line, but it doesn't appear to be working and it lets 12v through any time the key is on. I'm wondering if the PO used to start it by holding that switch down to let power go to coil when cranking and once it was running it somehow got power in another way. It was also running through a ballast resistor, which I have temporarily bypassed because everyone I asked says you don't need a resistor on an HEI. Back to the fried wire. Since I got this truck, I never knew leaving the key on could be bad for the coil and I probably had the key on countless times to let the radio play while wrenching on it. Could it be that leaving the key on could have heated the wire enough to melt that? Ooooohhhh, wait a minute! Now that I think about it, I accidentally did leave the key on overnight right before the trouble started. The next day I pulled it out and didn't think anything of it because I had a trickle charger on the battery anyway. So maybe I fried the wire then. It makes sense because it fired right up the last time I had the carb on it and this was right before I got the carb back from the shop while I was working on turn signals. oops.

I wrapped the damaged wire with 130c splicing tape and it seems to start up and run just fine now, no arcing. Although, I haven't let it run for more than about 30 seconds so far because I am still working on some things. So did I do this that night with the key on? Still doesn't explain why I don't have power from the ignition switch, unless something in there shorted that night too.

 

[Living in the Past]

My guess the ignition switch changed in 7/70 with the 71 model. Biggest difference is this was not separate wires but instead a plug. 9/72 the switch moved to the steering wheel and completely different. When I bought my 68 back in 1974 the ignition switch had been replaced with another OEM switch. The driver's door and and rear hatch were one key and ignition switch was another. I lucked out and the original bad ignition switch was in the glovebox. The key tumble was the same and was able to switch the old key tumbler into the other switch so all keys matched until I installed front door off a 79 in 1983. Gain a lock on the passenger's door but now needs two different keys. If you can find a old used ignition switch may be possible to switch tumblers to match the driver's door and rear hatch if yours is a original hard top.

 

[Maestro]

Like yours, my door key and ignition are different keys. I don't even have a key for my door, so maybe now would be a good time to sort this out properly so I can lock the door too! I don't have a cylinder on the passenger door and my rear hatch is a tailgate with accordion type doors which also have no lock. It's such a pain to open, I never worried about anyone actually being able to open it. It may have had an interior locking mechanism that is gone, but that's a problem for another day!

Whoa, sorry for the giant photo.