Ignition System Operation

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Mar 12, 2014
Hey guys, long story short I have a cranking/ no start/ no spark right '94 1FZ-FE right now. I searched and found very little useful info. Also, my FSM doesn't have much detail as far as description of the ignition system. I don't wanna just follow the flow chart, I wanna understand how it works. Here's my understanding:
The igniter is inside the distributor, it gives a signal to the Engine Control Module which fires the coil ground. Correct? I have 12v+ at the coil but no pulsing ground signal. Haven't had time to check the igniter resistance before I had to leave for work today. School me on system description/ operation please. I understand the basics I just wanna know the control side. Also, does this truck have a crankshaft position sensor or does the igniter give tach signal and time the injectors correctly also? I could look myself, I know, but I have 4 minutes of lunch left and you're not busy anyway. That's why you're putzing around here, right?
I won't pretend to know the ins and outs of the ignition system, but I just went through a similar issue. Does your ECU have power? Do you have a check engine light?

This is a good place to start: https://forum.ih8mud.com/threads/97-lx450-not-starting.827182/#post-9497856

Go through the test process in post #15.

The EFI relay is notorious apparently, as are the fusible links. You've got power to the coil, so it's not the plug in fusible link.
Great, thanks for the link @cheddar bob, searching leads to tons of threads, many not as useful as this one.

Just from reading through briefly I'd bet it's my EFI relay. It has hiccuped a few times this summer then came right back while I was cruising down the road, which makes me think it's something that could possibly be intermittent, unlike a fusible link which is bad or good. I can't remember seeing the CEL either. Also it wouldn't start the other day, I thought because it had no fuel. I sprayed some starting fluid in and it fired up for a sec. Sprayed a little more and topped off the 1/4 tank of old fuel I had with 5 gallons of warm fresh fuel and then she stayed running. Maybe whatever it is was just acting up them and I thought it was no fuel condition. The starting fluid didn't work today, so I checked spark and here I am.

I know my thoughts are all over the place but it could be a chewed through wire somewhere too, that was just on the verge of breaking. This truck sat in a barn for 2 months after I rolled it late last year and I know there were mice around: they ate all the ketchup packets in the glove box and left me little presents.

I'm still interested in the theory of how this ignition system operates. Even if anyone has a page to refer me to in the FSM. The digital copy I have is organized a little funny (hey it was FREE!). Thanks for the help and tips. Hopefully this thread is useful to others as well.

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