Ignition? (4 Viewers)

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5volts seems low to me, and if true likely your issue.

Test the resistance between the distributor case ( ground) and the negative side of the battery - should show as a short.
 
DeskJock said:
5volts seems low to me, and if true likely your issue.

Test the resistance between the distributor case ( ground) and the negative side of the battery - should show as a short.
Click to expand...
Thats what i thought too, so i ran the ohms meter across everything i could think of, and all seems really good. Ineven rannit from the power post of the ballest, and the case of the distributer and that whole lenght has minimal resistance (maybe 2 ohms). The 5v comes when the points are closed and the circut is altered between firing, 10+ comes when the points are open and firing... is this correct or within reason? Or should that not change? My understanding is thats what the points are for.
 
DeskJock said:
Well. That ballast may have degraded and maybe creating too much resistance.

The manual has the resistance value. If you need me to look it up- I will.
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Very good point... i did take it off and spray it with elec component cleaner and hit the posts with steal wool. I didnt find anything in my FSM about the ballest... if you have that number, id love to check! Thank you!
 
Might be time to start looking at the FSM for your year.

With all that you have changed out, there's a chance that something you reinstalled is either not wired correctly or not the right part for your vehicle.

That low voltage reading on your coil (+) (5v) seems suspect to me.

Is it possible you have the wrong coil, ie. one with an internal resistor? Or, you have some other IR drop between the ignition switch and the coil (+)?

To check that 12v line feeding your ballast resistor, with your battery terminals disconnected, check how many ohms you have between your battery positive terminal and your ballast resistor with the ignition switch in the ON position. It should be near zero.

If that checks out OK, that means you have too much current drawn downstream of that point.

I'm not a points guy, but I believe there should be no current draw through your ballast resistor or your coil when your points are open, coil lead out (no spark), and therefore you should have a full battery voltage at your coil (+) with your points open, your coil lead out (no spark) and ignition ON. Is that right?

If you want to start going through the FSM to verify the components in your ignition system, it's a great resource and a great way to learn. You can find the free download link here somewhere.
 
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So as I recall, during start, there's a wire coming off the starter and going to the + side of the coil to bypass the ballast resistor to help in ING start up. Idk, if that's the problem. Just say'n.
 
CruiserInProgress said:
Might be time to start looking at the FSM for your year.

With all that you have changed out, there's a chance that something you reinstalled is either not wired correctly or not the right part for your vehicle.

That low voltage reading on your coil (+) (5v) seems suspect to me.

Is it possible you have the wrong coil, ie. one with an internal resistor? Or, you have some other IR drop between the ignition switch and the coil (+)?

To check that 12v line feeding your ballast resistor, with your battery terminals disconnected, check how many ohms you have between your battery positive terminal and your ballast resistor with the ignition switch in the ON position. It should be near zero.

If that checks out OK, that means you have too much current drawn downstream of that point.

I'm not a points guy, but I believe there should be no current draw through your ballast resistor or your coil when your points are open, and therefore you should have a full battery voltage at your coil (+) with your points open and ignition ON. Is that right?

If you want to start going through the FSM to verify the components in your ignition system, it's a great resource and a great way to learn. You can find the free download link here somewhere.
Click to expand...
I totally get your point "point" and it makes sence. As i understand it, the elec points eliminat the ballest system, is that correct? My father purchased this rig new in 72 and I've been talking to him and as far as he knows... it's original. Could be bad?

I have the FSM and worked the binding off both books haha. but from what I have learned so far from purchasing parts from cruiser outfitters, there was a transition in my year AND month. Makes it so hard. Carb could be next to unique (april 72) and the manufactur month of the rig (May 72). In part of this research in the vacuum system, I've also learned the evaporative control is pretty unique also because of this. I have disconnected and reconnected the vacuum evap system with no change. I feel like the book covers a broader variety of years which is understood, but frustrating for specifics of transition years and months. My book makes little to no mention of vacuum or the parts of the ignition system other then the starter, coil, and basic dizzy (not vacuum retard but maybe vacuum advance with an octane set dial which i dont have). I thankful of those of you with real world, hands-on experience with this model.
 
pb4ugo said:
So as I recall, during start, there's a wire coming off the starter and going to the + side of the coil to bypass the ballast resistor to help in ING start up. Idk, if that's the problem. Just say'n.
Click to expand...

20250626_151314.jpg
 
pb4ugo said:
So as I recall, during start, there's a wire coming off the starter and going to the + side of the coil to bypass the ballast resistor to help in ING start up. Idk, if that's the problem. Just say'n.
Click to expand...
That cold start circuit is, or was, on my 79. When the oem starter is engaged, contacts are closed, providing full battery voltage to the coil (+), effectively bypassing the ballast resistor.

I don't know if that cold start / bypass circuit is part of the earlier 1F design , but if there was a malfunction or miswiring there, that could create a problem at the coil (+). Easy enough to disconnect that wire and measure voltage at coil (+) with ignition ON.
 
CruiserInProgress said:
That cold start circuit is, or was, on my 79. When the oem starter is engaged, contacts are closed, providing full battery voltage to the coil (+), effectively bypassing the ballast resistor.

I don't know if that cold start / bypass circuit is part of the earlier 1F design , but if there was a malfunction or miswiring there, that could create a problem at the coil (+). Easy enough to disconnect that wire and measure voltage at coil (+) with ignition ON.
Click to expand...
This is a new angle or direction... what is the "cold start circuit?" The choke cable includes a slight throttle advance, and the only elec connections is to a cellunoid on the carb, which clicks with power so I assume thats working.
 
Tigger72 said:
This is a new angle or direction... what is the "cold start circuit?" The choke cable includes a slight throttle advance, and the only elec connections is to a cellunoid on the carb, which clicks with power so I assume thats working.
Click to expand...
I discovered it on my 79 and tried to explain how it works above. If you have a wire connecting the starter to the coil (+), then you have one.

If so, try disconnecting it and see if you still have only 5v on the coil (+). If so, that's not the problem.
 
I know you said your '72 was a strange month, so its hard to see what parts you have. Have you looked at the electrical schematics?

For reference if you don't already have the link to Coolerman's diagrams: Coolerman's Electrical Schematic and FSM File Retrieval - https://globalsoftware-inc.com/coolerman/fj40/schematics/FJ40/

In all cases, I don't see the cold-start wire from the starter motor to the coil, and none of these schematics show a ballast resistor (but this may just be an erroneous omission there, as the '74 diagram does show a cold start wire, but no resistor, which would make no sense). This is not to say that if you have different parts / wiring that the setup won't work, just gives you a few more variables to clear.

If you do have a ballast resistor, there is good sense in having that cold start wire, but I don't think that would be the primary causal factor here. Up until very recently my truck was missing that wire (and it should have been there), but all it did was result in longer/harder starts. Once going, the engine worked fine. I think your t-shooting efforts should clear out the rest of the ignition system first.
 
Ill check my manual at home, I have a 1975 that according to grok is 1.4 to 2.4 ohms

Expected Resistance:

For a 1972 Toyota Land Cruiser with points ignition:
• Ceramic Ballast Resistor: Typically 1.4 to 2.0 ohms.

When I moved off the AFFORDABLE fuel injection and electric ignition last year to the factory setup - I think the voltage after the ballast was close to 10 volts. Middle 9’s or a tad higher.

Moving to Pertronix- to me is highly recommended.
 
I think 10v to the ballast is too low. I think It should be closer to batt voltage and be near 12v or more. 11.7 battery volts is low. It should be over 12volts. Have you tried a jumper wire from the + batt terminal to the input side of the ballast resistor? When you do this, is the output side of the ballast going to the coil higher than the 5v. The ballast resistor reduces the voltage to the points so they last longer. When the points are closed the circuit is energizing the secondary windings in the coil and when the points open the secondary wiring releases high voltage energy. If you go with petronix, it will require 12Volts at the + side of the coil.

I don't think there's a cold start circuit. If you have a bypass wire from the starter to the coil, it supplies 12v to the coil during cranking regardless of the temps.
 
Ok, here is an update. Replaced plug wires. Another improvement, more drivable, but still rough and exausty. I did check the ohms between the ballast posts and got 1.9 ohms. In the window you mentioned @DeskJock . It isn't visably ceramic though, it's metal bodied with some form of spring wrapped wire between posts. (Maybe spring wrapped ceramic?) Then I checked again from top of ballast to dizzy and read 2.1 ohms. That was read when cold. Also, Confirmed no wire between starter and ignition. I did leave the points at the highest dwell i could achieve with .1 mm gap = dwell of 35. Should i change that and go back to .45mm gap as the book recomends, even though i read closer to a dwell of 29?

@pb4ugo i did try the jumper between the battery and the + post on the ballast and there was no change.

Question, if there is another aspect of failure in the distributer its self, would elec points still work. Example... would slightly too much run-out in the armature not allow the pertronix to work appropriately, or is it less sensitive to a slight wobble? The needle on my dwell meter is very stable though so would this mean I dont have the exsesive run-out I think i might have? Another distributer issue?

Thank you all again for the help!
 
Electronic distributors have a reluctor/star wheel and a magnetic pickup. When a point of a star passes by the pickup magnet it fires the coil. The shaft bearings can fail in both types of dist, along with mechanical advance weights and springs, or the points cam can wear. The point gap measurement and dwell angle should net a similar result. Dwell is more accurate. To set the points by dwell it's easier if you have someone crank the engine while you set the points. This video is helpful. I use 2 screwdrivers, one on the adjustment notch and the other on the hold down screw and ready to snug it up once i have my desired dwell reading. .

 
pb4ugo said:
Electronic distributors have a reluctor/star wheel and a magnetic pickup. When a point of a star passes by the pickup magnet it fires the coil. The shaft bearings can fail in both types of dist, along with mechanical advance weights and springs, or the points cam can wear. The point gap measurement and dwell angle should net a similar result. Dwell is more accurate. To set the points by dwell it's easier if you have someone crank the engine while you set the points. This video is helpful. I use 2 screwdrivers, one on the adjustment notch and the other on the hold down screw and ready to snug it up once i have my desired dwell reading. .

Click to expand...

As I think about this more and will definitely try this process and focus on dwell (great video! Thank you!), I have replaced and set the points in past years without this rough running. I do believe that process will be more accurate and excited to try, but unless I magicly nailed the point gap with a feeler gage on the past and then it slipped into a better spot before the issue started (honestly realistic as they got damn near to closing when it stopped idoling and i readjusted.) I still feel like we havnt touched on the root issue. Aside from ignition, what other system could be failing?
 
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