Troubleshooting electronic ignition ('78 FJ40)

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Still no spark :crybaby:

I went back and rechecked every connection in the harness, all fuses, and everything else I could think of.

Next, I cleaned the bracket for the coil/igniter combo and made sure everything was clean. Swapped in a known good battery, delivering 13.05 volts, clamped the end of a heavy duty stranded copper wire into the negative terminal clamp to insure solid connection, and clamped this wire to the igniter bracket which is also the ground for the igniter. :princess: cranked the engine while I held the HT lead from the coil to the valve cover. Nothing! :frown: Not even the previously noted miniscule yellow spark. Pulled the HT lead and checked it - showing 14 kOhms, so it is good. Re-tested the coil for spark - good. Rechecked the power to the igniter at the connector - 12.4 volts. Rechecked the ground jumper - it was solid. Since I couldn't think of anything else to check at that point, I tried a different battery, delivering 14.05 volts, but the results were the same.

The only differences from previous attempts to get a spark were the total lack of spark and the fact that the coil and igniter both got warm this time - not hot, just warm, which I think must be normal for the electronic components.

I will check with Toyota tomorrow to see if they have the igniter or a substitute. I'll also check a few of the parts shops in Old Town - many of them sell used parts taken from wrecked cars, as well as new, mostly knock-off parts. I might get lucky there. Most wrecks here are rebuilt. Rebuilt rollovers make up a large part of the panel beater business, and vehicles that go to the car breakers are usually quickly stripped of anything that might be reusable.

Wish me luck :)
 
M5driver said:
Still no spark :crybaby:

Re-tested the coil for spark - good.
Click to expand...

Did you hot wire the coil too?

So that tends to indicate that either the ignitor or pickup is bad. Did you check the resistance of the pickup? I think that there is a spec for that in the FSM. You could probably check the ignitor by putting a weak battery (<1V) across the ignitor leads to the distributor and check for a spark.
 
Pin_Head said:
Did you hot wire the coil too?

So that tends to indicate that either the ignitor or pickup is bad. Did you check the resistance of the pickup? I think that there is a spec for that in the FSM. You could probably check the ignitor by putting a weak battery (<1V) across the ignitor leads to the distributor and check for a spark.
Click to expand...

I checked the coil a couple of times using your instructions and it seems to be good. I get the expected spark. I haven't checked resistance in the pick-up. The air gap is good. I will check my FSM to see what it shows on the pick-up and what to test.

The FSM also shows a test for the ignitor which uses a 1.5v battery across the leads, but points out that if this test is not done quickly (<5 sec) it can damage the ignitor. Until I have a replacement unit in hand, I prefer not to try a potentially destructive test :)

Thanks again for the help. I'll post up anything I find out.

:cheers:
 
Stupid question.
Did you check that there is power in both (blk/yel) wires that feed the igniter ,with the key turned ON?
 
Go ahead and do the ignitor test with a battery. The FSM isn't going to tell you to do anything that will destroy your ignitor. You only need to "connect" it for a millisecond to get a spark. Use a "dead" battery if you are worried as you only need a few millivolts to trigger the ignitor.

Knowing whether the ignitor is bad is useful information.
 
bsmith123 said:
I think there is a required air gap on the sensor so check the FSM and make sure that is right

How about the high tension lead itself?
Click to expand...

Forgot to answer this earlier :o Air gap is .012. HT lead shows 14 kOhms, manual calls for <25 kOhms, so these look good. I didn't find anything in my FSM about testing the pickup, so I still don't have any data on that.

Still working my way through this. Just to verify - or discount - my own testing I am taking coil, igniter, and three batteries to the indie I work with here to re-check as much as we can. I'm leaving the dizzy in place, tho. We're looking for a replacement igniter somewhere on this end of the continent. Toyota Malawi doesn't have the part here in Lilongwe, but the GM is checking Blantyre, Lusaka, and Johannesburg to see what might be available. I'm checking to see what I can get from the US, even though it will take several weeks to get here. Checking with the better parts houses here yielded nothing, and the car breakers basically have nothing available from the 70-80s vehicles. It seems there is not that much that can go wrong with this set up, so we'll get it sorted. I may have to ask the Toyota GM to send his auto electrician to check the system with me and see if he can find anything I've missed. His reputation here as an electrical system troubleshooter is formidable.

I'll post whatever we discover.

:cheers:
 
Coolerman said:
Any chance you could scan that page or at least post the text from the FSM? I would like to add that to my knowledge base. :idea:

Hope you can get a replacment for it!
Click to expand...

I'll see if I can scan the page before the weekend and post it up here for ya. :D
 
sensor pickup

You could try shooting the pick up for shorts and continuity anyway.

If it is in MEGAOHM range I would think that would be bad too
if it is shorted to case or through the wiring you can see that and if it reads open you'll know its bad for sure eh?

Post up the ohms you read and maybe someone can check theirs for comparison

I wouldn't recommend shooting into anything electronic unless you have a schematic cause you can screw up components but this should just be a coil and I have seen specs for other pickups

If it is shorted or open you dont really need the specs for that

Best of luck and send us some out and about pics once you get her going!:steer::steer::steer:
 
Coolerman said:
Any chance you could scan that page or at least post the text from the FSM? I would like to add that to my knowledge base. :idea:

Hope you can get a replacment for it!
Click to expand...

Coolerman - here are the pages I am working from in my FSM.
FJmanual_ign2.webp
FJmanual_ign1.webp
 
To my amazement - and perhaps good luck - Toyota Malawi had an igniter assembly in Blantyre that might work. It was sent here to Lilongwe; I picked it up today.

The GM thinks I can just wire it up and go. It will require cutting and replacing plugs, tho.

I decided not to jump right into it until I get a little advice here. The wiring on the new box is virtually the same as the old one, but not quite. I took some photos to try to show what I am looking at and my hesitation to cut wires without first asking the experts here :)

The first pic is the old box installed with my ground jumper to the battery negative.

Second pic is the new box and the old box.
Old-box.webp
Old-and-new.webp
 
The leads to the coil are a bit different on the new box. The black lead to the negative coil terminal looks more or less the same, but on the old box (right side) it looks like there was a double black lead and one is cut off. FWIW, I did not change the box myself when the old one croaked; I had it done by a mechanic in Sofia, BG, since I couldn't get off from work to take care of the problem. The other leads are a bit different also. The light yellow lead on the old box goes directly from the power plug to the positive terminal on the coil. It feeds from the heavier gauge black/yellow lead from the wire harness.

Looking at the leads on the new box, it looks like the black would go to the neg terminal, and the double tan lead to the pos terminal?

The pink & white leads to the distributor are the same. The power leads are the same, but the light yellow and tan wires that come off it don't exactly mirror that on the old box. Next set of pics shows that.
Coil-leads.webp
Distro-wires-old-new.webp
Power-Plugs-old-new.webp
 
Last edited:
Old box wires

Light yellow from power plug heavy gauge line to coil +
Black to coil -
Tan from power plug light gauge black/yellow to box
Green from box to ground on the box case
Pink and White to distributor
Old-box-wires-1.webp
Old-box-wires-2.webp
 
New box wires

Tan from power plug (heavy gauge or light gauge black/yellow?) to coil + to box (doubles back from ring terminal)
Light yellow from power plug (which wire?) to box
Black from coil - to box
Pink & white to distributor
No green wire
New-box-wires-1.webp
New-box-wires-2.webp
New-box-wires-3.webp
 
So here are the questions:

1. The power wires both carry 12 v, but from different gauge leads. On the old box, the light yellow lead goes from the heavy power lead to the coil + and stops there. The tan power lead goes into the box. On the new box, the yellow goes from one of the 12v power leads to the box; the tan lead goes from power to the + terminal on the coil (?) and back to the box. Why the difference? If I cut the plug off the new box, should I wire the tan lead (goes to coil +? ring terminal) to the yellow lead from the old box plug (goes from power to coil +)?; and new box yellow lead to the old box tan lead on the plug? (both go from power to box).

Is this confusing?

2. Why is there no green lead on the new box (on the old box, it exits the box and is attached to the box housing (ground?)

What am I about to screw up? I only get one chance at this. There is apparently no other igniter assembly available, at least from Toyota, at this time.
 
M5driver said:
Is this confusing?

.
Click to expand...

Yes.

The ignitor needs 5 connections.

1. 12V power (usually from the + side of the coil)

2. A ground (often the case is the ground, but it may be a wire)

3. - side of the coil (to trigger the spark)

4, 5. 2 distributor pickup leads

It may also have an optional wires for a tachometer.

How do you know the ignitor is bad?
I have seen 3 bad pickup coils and 0 bad ignitors.
 
isolated

Earlier we told him to hot wire the coil with the other wires removed and check for spark by the wire touch from the - coil post

That should rule out the pickup although i did suggest ohming for shorts and opens anyway----since we dont know the spec for the resistance--- and he checked the air gap too
 
Pin_Head said:
Yes.

The ignitor needs 5 connections.

1. 12V power (usually from the + side of the coil)

2. A ground (often the case is the ground, but it may be a wire)

3. - side of the coil (to trigger the spark)

4, 5. 2 distributor pickup leads

It may also have an optional wires for a tachometer.

How do you know the ignitor is bad?
I have seen 3 bad pickup coils and 0 bad ignitors.
Click to expand...

1. 12V power (usually from the + side of the coil)-- OK, this would be the tan wire that goes from the power plug to the + coil to the box?

2. A ground (often the case is the ground, but it may be a wire)-- The entire box is cast metal... it appears the ground may be the case itself. I do not see a ground wire like the green one on the old box that goes from some internal connection in the box to the case. So I vote for the case being the ground.

3. - side of the coil (to trigger the spark)-- I would say the black lead that goes from the box to a ring connector. I am guessing this is the - terminal connector for the coil.

4, 5. 2 distributor pickup leads-- This would be the long pink and white wires, the same as the old box, right?

This leaves me with the light yellow lead that goes from the power plug to a mystery connection in the box, right? So as I see it right now I have tan wire from power to + coil to some mystery connection inside the box; black wire from inside the box to - coil; white and pink to distributor, and yellow wire from power plug to another mystery connection in the box. Ground is probably the box itself.

So, if I decide to do the $300 experiment, will it make a difference whether I have the tan wire going to the smaller or larger of the black/yellow power leads in the harness; ditto the yellow wire?

How do you know the ignitor is bad?-- I don't. The only thing I know with any certainty right now is that I am not getting a spark from the coil when I pull the HT lead and check for spark. I do not see the voltages the FSM says I should get at the coil terminals. And, I have had ignitors fail before, on this and other vehicles.

This morning, I will replace the battery with a better battery, since during the week, I had the chance to recharge and test the existing battery; it is weak and cannot handle a full load. Then I will test the coil by hotwiring the + terminal and momentarily grounding the - terminal. If I get a decent spark, then I can assume the coil is good. If not, then I will see if I can find another replacement coil and go from there. I will check the distributor connector to see what sort of readings I might get from the pickup. It is still possible that this is the bad component. This is not something I have been able to locate here yet. Stuff to fix old petrol engines is hard to find; this is essentially a diesel-driven country. If the coil is good and the pickup appears good, (the magnet part works - my feeler gauge sticks to it :) ) then I will try again with the old igniter. And so on. The last step will be to cut plugs and install the new igniter box.

Thanks for putting up with me and all the questions. I'm really out of my depth with non-points ignition.

:cheers:

Dan
 
For $300, I wouldn't experiment with an ignitor that is not plug compatible and does not have a schematic diagram with it so you can stop guessing about what the wires are. I would do the battery test on the ignitor and ohm out the pickup coil. You should get a spark when you put a battery on the pickup wires with the ignition on. There must be a resistance spec for the coil.

There is no way I would know which wire is which without a schematic.
 
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