Stumped with No spark - distributor pick up ?

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I have a 1983 Toyota Cressida (5MGE) with about 200k miles and it was running fine. However when my wife went to get the kids from school it wouldn't start at all. The engine is turning over just fine but no ignition/starting. It has fuel and the timing belt is intact and was verified by watching the cam turn via the oil fill hole.

I cannot get any spark from the plug wires or the coil wire so I'm working up stream to try and figure out why not.

Since it isn't producing any sparks or fire at all I figured the
ignitor had failed as this has been somewhat of a common problem with the older Toyota's. I had picked up a spare ignitor and coil a few years back at a salvage yard. I changed out the ignitor/coil assembly thinking how impressed my wife
was soon going to be when I fixed it but much to my surprise there was no change - still no spark to be found anywhere.

So I humbly pulled out my Toyota factory manual and started testing to try and figure out why there is no spark all of a sudden.

Here is what the factory manual recommends and what I've done.

1. Verified that there is 12 volts getting to the ignitor with the key in the on position - - OK here as I'm getting the 12 volts.

2. Checked that the "power transistor (whatever that is)" in the
ignitor is working by putting 3 volts to one of the wires coming from the ignitor and the other to ground while the key is in the on position. This is suppose to result in a burst of sparks, within 1 second, at the end of the coil wire tip that was disconneted from the distributor cap end. It worked perfectly, as the open coil wire end started sparked almost immediately. I believe this confirms that the ignitor and coil are working OK and not the problem.

3. Next step, per the manual, is checking out the distributor "pick-up coil" by using a multi-meter to check the ohms. I got 153 ohms across both terminal ends (I think one was called NE and the other G) at the end of the wiring connection which is spot on according to the factory manual.

That is the end of the factory manual diagnostics so am trying to think of where to go next. The plug wires are almost new but I cannot get any spark from the coil wire so it appears to be in the primary ignition system. The car has been a daily driver and
was starting and running normally until this happened.

One thing that I have read from other web locations about other makes of cars is that some have mentioned that there should be continuity between the two leads on the distributor "pick-up coil" but the Toyota manual doesn't address this test. I went ahead and did it since I was already there and I did note that my test showed an open b/t the two terminal ends - or no continuity. I don't know if that is pointing to the problem or not since Toyota didn't mention this at all.

Also, I've read about pulling the distributor cap and checking the air gap. However since there is no contact with the pick up coil assembly I don't see why the gap would have grown over time?

I have read that the ECU (computer) is almost never the problem and the manual doesn't even address testing it so I'm hoping that isn't it and I'm trying to rule out the distributor first.

Should I just buy another distributor or is there other test to confirm that the distributor (and pick up coil) is operating properly and sending the signal to the ignitor?

Any thoughts or ideas of what I may be overlooking would be ppreciated.
 
1983 Cressida shall have one of those individually operated electronic ignition which comprised with a pick up coil/hall effect coil or similar built in to distributor unit, an ignitor module + a transistorised ignition coil pack. It is not monitored/controlled by ECU.

So there you have it! look for broken/burnt coils, open resistance in coils and also possibly (and highly likely the primary cause)a bad ignitor.

Mind you though: I tend to fault the high tension ignition coil packs and ignitors for these units may fail due to moisture/corrosion, and as for ignitor modules, they have a built-in service life to them.

Q.
 
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I recommend checking that ECU. I think if it doesn't ground properly you don't get spark. The ECU might not usually be the problem, but then again, it's 25 years old.
 
put a voltmeter from that 3 volt ignitor wire to ground, then crank the car. The meter should bounce from 0-3-0-3-0-3-... quickly (likely won't register a full 3 volts). If it does not, then go upstream to the ECU.

You might want to repeat the test, measuring V across the hall effect sense. MUST use a digital VM for this since they are more sensitive and don't impose as much of a load on the tested circuit. You should see flucuation accross the hall sensor.

M
 
The problem you describe sounds exactly like the way my old '78 Cadillac acted when its distributor pick-up coil went out. How did I know it was the pick-up coil? I didn't; my neighbor down the street is a GM master tech electronic brain. He did all the troubleshooting and then showed me how to remove the coil after I took out the distributor myself and took it down to his house. I reinstalled the distributor and the big 425 fired right up.

As I remember, the first thing you do is punch out the roll pin that holds the distributor gear on; then there's some kind of snap ring that goes around the distributor shaft that gets removed too; then the pick-up coil slides off the end of the distributor shaft. I'm just going by memory because I don't have the car anymore. The pick-up coil is one of those kind of parts that will look perfectly fine and then stop working all of a sudden.
 
Thanks for the idea's!

Today I tried to get a voltage reading coming from the distributor pick up coil as Meep suggested. First I confirmed the same leads (NE to G and G1 to G) that gave me the spot on Ohm readings again. This the same 153 Ohm reading as yesterday which are on spec and seem to indicate no problem.

However I could get no DC voltage reading (not even a flucuation) from these leads while using a digital meter with the car cranking over at normal speed.

I think that points to either a too big of air gap or bad distributor despite the correct Ohm readings? I don't know why the air gap would have changed though.

Is it time to get a new or salvage distributor or can an alternator shop replace the pick up coil?
 
you are not supposed to get a dc voltage big enough to register on your digital voltmeter, so long as you have a proper resistance reading (in terms of ohms), you are fine.

Don't tamper with the magnetic air gap on your distributor or you may screw things up even further, unless your distributor shaft bearings is bad, causing the gap to vary (happened once to one of the Honda civic dist I serviced, but rarely)

Don't delay. Go find a used ignitor and swap out your old one and see.

Q.

p.s. your pick up coil inside the distributor is fine so no need to fiddle with it for you need something more sensitive than ordinary digital voltmeter in order to pick up that minute pulse. Don't just assume things here....
 
I think he said he swapped the ignitor already.

It's possible that the ignitor he used was bad. He did say it came from a salvage yard...
 
Ignitors are the first thing to change, and most will do this automatically when there is no spark.
Yes, the 'new' one may also be faulty;
 
I thought it would be the ignitor too so, yes I did change out the ignitor and coil assembly with one from the salvage yard. It made no difference.

So I tested the ignitor as per my factory manual by applying 3 volts to it (with a DC battery) while the key was in the on position. This immediately caused the end of the coil wire to make lot's of sparks. (The end that normally would attach to the distributor). So that seems to confirm that the ignitor and coil are able to produce sparks if they get the proper imput signal??

I assume this is supose to be similar to the voltage input that ends up coming from the distributor pick up coil when the engine is turning over ? - as I don't think the ECU produces the raw input - - only somehow controlling the timing of it) I guess that is why I'm trying to rule out the other parts before pointing the finger at the ECU. If the on spec Ohm readings tell me that the distributor is OK - even though I can get no signs of any DC signal coming from it when cranking - is it time to go to the ECU or is there another test of the pick up coil on the distributor?

I think I'll try what Meep said and see if I can get a reading:

"put a voltmeter from that 3 volt ignitor wire to ground, then crank the car. The meter should bounce from 0-3-0-3-0-3-... quickly (likely won't register a full 3 volts). If it does not, then go upstream to the ECU."
 
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First of all. . .

Do you know how to position the engine at #1 TDC on the compression stroke before pulling the distributor out?

Do you know how to hook your ignition wires up by firing order?

Do you know whether your distributor turns clockwise or counterclockwise?

I had already given you the benefit of the doubt and assumed you knew this stuff.


It's either the primary/secondary coil, the ICM, or the pickup coil; with the pickup coil being the only thing you'd have to pull the distributor out for changing.

Being that I forgot what my neighbor told me as far as determining which one is at fault, I'd probably start throwing parts at it until the engine fired up.
grin2.gif
 
SOLVED...

It was the ignitor.

I'd pulled the 15 amp fuse going to the fuel pump so as to not keep pumping gas into the cylinders when I was test cranking. Turns out that fuse was also supplying power to the ECU and as soon as I determined I wasn't getting power there I new I'd done a bone head mistake of not putting it back. Put the fuse back which showed power to the ECU and of course it fired right back up. (Just another example of me turning something relatively simple into an all day job.)

Thanks for the input as that really helped me to think through this darn thing.
 
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