I don't think it's the coil,igniter,or pickup. Am 99% sure A 12v coil test won't hurt anything , and will tell you if it's a ballast problem. If it still won't run after the test, my next guess would be pickup.
1979 FJ40 no spark issues (I have read all the threads on this issue) What am I missing or failing to check
- Thread starter Wadesters
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I ohm'd it at 177. Tolerance is 150-180. Seeing as it was near the upper limit and the accuracy of my multimeters is suspect. I think you're on to something.
Luckily I have a newly rebuilt distributor that has a new signal generator (Pick-up) that ohm'd at 155. Looks like I'll be replacing the distributor tomorrow.
I will check that before I swap the distributor out.
If the pickup coil is OK, then maybe there is a fault in the wiring harness somewhere between the ignition key and the distributor. It is possible that you could have doinked it while replacing all the other stuff. Try hot wiring it from the battery + to the igniter and coil to rule out the power side of the wiring.
Ok so when I jumper the + coil post to the battery +. The Ignition switch turns on, with no key in. So this is indicative of a wiring short?
When I do this, I hear the carb idle solenoid click, the starter solenoid and the seat belt warning buzzer.
When I do this, I hear the carb idle solenoid click, the starter solenoid and the seat belt warning buzzer.
Ok. So I went through the schematic. The ignition circuit coming ON when I jumped the Battery and Coil + posts is normal & makes sense as the two wire plug that supplies 12v to the coil and ballast is grounded when the ignition switch is in the off position.
I then jumped the battery and coil + posts and she fired right up and I let her idle for about a minute.
I am getting 12v at both terminals on the two pin plug at the ignitor with the ignition ON but when the thicker of the two Black / Yellow wires i.e. the one that goes through that plug and goes directly to the + coil post, is connected to the coil, the voltage at the + coil post only shows 7 volts. However, as soon as I remove the one and only wire to the + coil post it shows 12v again.
Also, in examining the wiring diagrams posted here and on Coolermans's site, I do not have a bypass/exciter wire going from my starter to my coil. There is not a any unattached wires by the ignitor or starter. Is this an area of concern
I then jumped the battery and coil + posts and she fired right up and I let her idle for about a minute.
I am getting 12v at both terminals on the two pin plug at the ignitor with the ignition ON but when the thicker of the two Black / Yellow wires i.e. the one that goes through that plug and goes directly to the + coil post, is connected to the coil, the voltage at the + coil post only shows 7 volts. However, as soon as I remove the one and only wire to the + coil post it shows 12v again.
Also, in examining the wiring diagrams posted here and on Coolermans's site, I do not have a bypass/exciter wire going from my starter to my coil. There is not a any unattached wires by the ignitor or starter. Is this an area of concern
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The voltage at the + side of the coil always oscillates between 12 and about 7 V during operation. When the igniter is grounding the coil - to energize the coil, it will read 7V. When the igniter interrupts the - side ground the magnetic field in the coil collapses to make a spark, then it will read 12V. Repeat for every spark. During running you would need an oscilloscope to see this fluctuation.
If it runs when you hot wire the + side of the coil, but not without the jumper, it suggests that the power feed wires have a bad or high impedance connection that does not let enough current flow. Go through these connections one at a time and shine them up and tighten the all the way back to the key and see if your problem goes away.
Do you have two small wires connected to the starter solenoid or only 1?
If it runs when you hot wire the + side of the coil, but not without the jumper, it suggests that the power feed wires have a bad or high impedance connection that does not let enough current flow. Go through these connections one at a time and shine them up and tighten the all the way back to the key and see if your problem goes away.
Do you have two small wires connected to the starter solenoid or only 1?
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Thanks. I will go trace dow the wires/connections to the starter switch.
I only have one Black and white wire going to the starter.
I only have one Black and white wire going to the starter.
So where does the black wire with the yellow stripe end up that looks like it is going under the starter? This may be the resistor bypass wire. Do you have a loose black wire with yellow stripe wire near the coil?
Since you get 7V at the coil + when everything connected, it suggests that the large power wire is OK. If it dropped to 0, then it would be a problem. Check the voltage at the smaller wire connector with everything connected and with the key on. It should not drop much below 12V. If it drops below 10 V, the igniter won’t run. If it drops, then the wire or its connections upstream are bad. Check this smaller wire before you fool with the ignition switch.
What is the voltage at the + lug of the coil during engine cranking?
Since you get 7V at the coil + when everything connected, it suggests that the large power wire is OK. If it dropped to 0, then it would be a problem. Check the voltage at the smaller wire connector with everything connected and with the key on. It should not drop much below 12V. If it drops below 10 V, the igniter won’t run. If it drops, then the wire or its connections upstream are bad. Check this smaller wire before you fool with the ignition switch.
What is the voltage at the + lug of the coil during engine cranking?
the 7v is just coil run voltage supplied by ballast. It's 12v when cranking to aid start.
You have to find the inline ballast and replace it or short it out. That's all the issue is most probably.
All the ignition lights and carb solenoid coming on is normal with the original wires still connected to the coil +
You could disconnect it/them and do the bat-coil test and it should still run.
good luck
You have to find the inline ballast and replace it or short it out. That's all the issue is most probably.
All the ignition lights and carb solenoid coming on is normal with the original wires still connected to the coil +
You could disconnect it/them and do the bat-coil test and it should still run.
good luck
The black/yellow wire under the starter is the starter ground to the frame. There is no loose wire near the starter neither black/yellow or black/white. The only wire there is the black/white from the ignition switch that is attached to the starter tab.
The coil + remains 7v constant when running with a healthy ballast. Remember the ballast's only function is to protect the coil. When cranking the circuit flips to 12v to aid starting.
If the ballast is dodgy, the voltage can drop lower when running becase of heat build up. I think this is what has happened to yours.
Your wiring is probably a-ok.
The new coil you fitted probably draws a bit more current and over-stressed the ballast. The running for 30 mins only points to this as a possibility.
If you try a coil with that draws the least current [highest resistance primary, or highest ohms] it might even run with your “Yazaki” wire setup .But I would be replacing the “Yazaki” all the same. Are they available?
If the ballast is dodgy, the voltage can drop lower when running becase of heat build up. I think this is what has happened to yours.
Your wiring is probably a-ok.
The new coil you fitted probably draws a bit more current and over-stressed the ballast. The running for 30 mins only points to this as a possibility.
If you try a coil with that draws the least current [highest resistance primary, or highest ohms] it might even run with your “Yazaki” wire setup .But I would be replacing the “Yazaki” all the same. Are they available?
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You probably mentioned these items earlier but I just wanted to ask, does your A/C work and do you have all your emission components in place and working?
Chances are that the black/yellow stripe wire under the starter is the resistor bypass wire and it should not be grounded. The PO may have changed the starter to the type that does not have the bypass connection. There should be another black/yellow stripe wire near the coil that ends in a ring terminal.
The ballast resistor is built into the wire in ‘79. It is the so-called “Yazaki” wire for the name labeled on the wire.
You don’t need the bypass circuit, especially if you don’t live in the snow country.
You do need to check that the voltage at the igniter does not fall below about 10V when engine cranking.
The ballast resistor is built into the wire in ‘79. It is the so-called “Yazaki” wire for the name labeled on the wire.
You don’t need the bypass circuit, especially if you don’t live in the snow country.
You do need to check that the voltage at the igniter does not fall below about 10V when engine cranking.
There are no other connectors near the starter. The black and yellow wire is the bonding strap to the frame. I think I may have found my issue, I went to check the connections of the fusible link and a link pulled right out of the terminal.
The AC does not work but I do have all of my emissions components. I even swapped in a different emission computer with no change prior to noticing the broken fusible link.
I have a spare harness to dig into to find the pink Yazaki resistor wire. Unfortunately there is no fusible link on it. Guess I'll have to order one from @Coolerman
As soon as I get a new fusible link I'll be able to check the B/Y wire to ballast to see if it drops below 10v
Either you or I may be a little confused. The large black/yellow wire is the ballast resistor. There should be no other ballast resistor.
The small B/Y wire is the power to the igniter. You should check the voltage on this wire during engine cranking.
The small B/Y wire is the power to the igniter. You should check the voltage on this wire during engine cranking.
Good find. That could certainly explain your problems!