1979 FJ40 no spark issues (I have read all the threads on this issue) What am I missing or failing to check

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The 1979 will have the built in Yazaki resistor wire instead of a ballast resistor. Make sure you are not using a separate ballast resistor as that would reduce the voltage to a point the ignitor/coil would not fire. Other than that I would start looking for continuity in the wires from the ignitor to the dizzy. If they are broken, no signal will get to the ignitor for spark. This can be hard to do. I use sewing needles to pierce wiring insulation so readings can be taken if there is no exposed way to get to the connection.
 
Not sure how the igniter could be wired wrong. However i do feel it must be a wiring issue. Also I upgraded the alternator.

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You don't need to run a high tension wire to the center post of the distributor cap. Eliminate the possibility of a shorted rotor or dizzy cap and just put a grounded jumper wire near the coil tower and see if you get at least a 1/2" spark when you crank the engine.
 
IT'S ALIVE! It does not make any sense to me but with another set of eyes it was suggested that I try another igniter (even though I tested the original one in a different FJ40).
I did try that before but had the plug with the yellow wire hooked up (for some reason that plug cancels power). With that plug unhooked (I think it goes to the emission box and I do not have emissions so do not need it) it has spark and fired right up.
So even though it worked on another vehicle something has to be wrong with the original igniter.

Thanks to everyone for your help with this!!

Chris..
 
FJ40Jim said:
The 2 wire plug is 12V to ignitor and ballast Voltage to coil. Both those need power to make spark.
Click to expand...
I’m replacing an HEI with a rebuilt 78 distributor/igniter. This two wire plug with a large Black/yellow stripe wire and a small black/yellow stripe wire has me confused. I thought the big wire went to the starter motor and the small one was connected to the ignition??? o_O I don’t want to damage my new old Jim C rebuilt unit
 
‘78 has a large (8ga) pink Yazaki Resistor spliced into the large (8ga) BY wire. The Yazaki replaced the ballast resistor 1978.

The small BY is full battery voltage... the large BY is < (resisted) full battery voltage.

I installed DUI a while back and no longer have the 8ga BY... it wasn’t needed for DUI.

Perhaps someone else can verify the routing for the large and small BY wires.

Here’s @Coolerman ‘s ‘78 wiring diagram... but IIRC, there are a few issues with wire colors... and I don’t think you can determine which BY is large and which is small.

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Wadesters said:
IT'S ALIVE! It does not make any sense to me but with another set of eyes it was suggested that I try another igniter (even though I tested the original one in a different FJ40).
I did try that before but had the plug with the yellow wire hooked up (for some reason that plug cancels power). With that plug unhooked (I think it goes to the emission box and I do not have emissions so do not need it) it has spark and fired right up.
So even though it worked on another vehicle something has to be wrong with the original igniter.
Chris..
Click to expand...
The yellow wire is tach signal output. If it is grounded, there is no spark. Sounds like there is a ground fault in the tach wire in the truck.
 
Slow Poke said:
I’m replacing an HEI with a rebuilt 78 distributor/igniter. This two wire plug with a large Black/yellow stripe wire and a small black/yellow stripe wire has me confused. I thought the big wire went to the starter motor and the small one was connected to the ignition??? o_O I don’t want to damage my new old Jim C rebuilt unit
Click to expand...

On a 78-80 ignitor unit:
The 2-pole chassis connector is 2 power inputs.
One is ballasted (reduced voltage) to the ignition coil.
The other is full 12V to power the ignitor itself.

The single wire is tach output.

And the long harness goes to the pickup unit in the distributor.

The whole assembly is grounded through the monting bolts, so make sure the fasteners aren't too rusty.
 
Reviving an old thread...

I have a '79 with a no spark issue too.

It started after replacing plugs, wires, cap and rotor. It just quit running after about 30 minutes.
I checked the coil and it was at @1.5 ohm on the primary coil and 13.0 ohms on the secondary. The primary was out of spec per the FSM value of 0.5-0.7 ohm so I bought a Napa coil and it ohm'd out to 1.5 and 9.5 so I bought another 90919-00823 coil from the dealer and it to is ohming the same as my original Toyota coil at 1.6 & 13.0.

I also ohm'd out a half a dozen other coils at several parts stores and couldn't find any the ohm'd between 0.5-0.7 ohm on the primary + & - posts.

I am wonder if the factory USA spec is wrong in the FSM or all of these coils are bad.

After reading through the thread I checked the vehicle side of the 2-wire plug to the ignitor both ground out with a continuity test.
I get 5.9 volts on the single wire plug.

I did the checks in the FSM and wrote the results in red.

I have also checked the wires for the ignitor for continuity and have no broken wires between the ignitor side of the plug and then ignitor circuit board.

Do you all have any suggestions?

Thanks
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Here is the body side of the wiring going to the ignitor. From left to right is the single Yellow wire from what I believe is the emissions computer and it was showing approx 6 volts with the ignition switch in the ON position.
The next 2-wire plug with a thin & thick Black/Yellow wires shows continuity with the block ground both with the ignition switch ON & OFF.
The last single wire bullet style connector goes to the condenser that grounds to the forward block lift hook.
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The other issue I found was with the electrical schematics. The 1979 shows a ballast resister and two + symbols on the coil. Wonder if that was a mistake or a carry over from the early '78's that had points.
So I looked at the 1980 and it appears to show the electronic distributor. Should I be using the later 1980 schematic to trouble shoot this?
 
Perhaps the coil is damaged from running for 30 mins on full 12v because the ballast was wired incorrectly. Have you tried other coils?

Edit scratch that , I see you have tried other coils. You could try a dedicated 12v coil and don't use the ballast.
Also I think the igniter needs full 12v? I had a chinese dizzy that I wired wrong . The module was getting the ballast voltage [approx 7v] and it used to run for a while and then conk out. Full 12v fixed it.
Edit again doh. If the igniter needs full 12v , but you ran it for a while at 7v , the igniter might be damaged.
 
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Thanks, @pithicus . I'll check the ignitor again.
I just put in a new ignition switch. The old one had a ton of copper dust in and around it. With the new ignition switch in, I am getting 12v on the black/yellow wires that were grounding out earlier. I'll hook up and test out the ignitor again tonight.

Hopefully, it will match the FSM tolerance and I can get on the restoring the AC.
Pictured are the readings with the new switch installed and the old switch with copper dust and old internals. I think the old switch is shot based on the new readings.
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That copper dust looks a bit strange. plenty of short circuit potential there lol.
With the ignitor possibly needing 12v, it might pay to wait for others to chime in. It may need lower voltage, so best be sure first , in case you damage it.
cheers.
 
Yeah, I cleaned all of that dust up after I removed the old switch. The old switch wires had been tapped into by a previous owner at some point using scotch loc fasteners. I soldered them up and heat shrunk them when I first bought it. Maybe that changed the resistance in those ignition wires. Who knows? It was a 41 year old switch. It was probably due for replacement.
 
I have 12v going to both B/Y wires to the 2 pin plug & confirmed continuity on the ignitor side from the plugs to the ignitor circuit board.
Does anyone have a 1979 specific manual to confirm the checks as it looks like the '80 manual I have been using is for the later style ignitor.
 
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