Yes, Ignitor = slang for Ignition Control Module.

It seems to be some kind of isolation amplifier to prevent spikes from the coil from feeding back & frying the ECU.

 

Jim,

I thought that the ignitor was basically a switch that charges the coil by grounding the primary lead of the coil at the proper time. The coil discharges a spark when the ignitor turns off the ground.

 

Yeah, that's how it works, but it's a solid-state device. Not a 'switch' in the sense of a solenoid relay with contacts that physically close & open. In the old days the breaker points did this by closing & opening the ground side of the coil's primary circuit.

The output transistors of the ECU could just as well do that switching all by themselves, but the ignitor can be made more robust so it can add a layer of isolation between the coil & the ECU.

disclaimer...
I don't design these things for Honda, I've never cut one apart; I'm only putting this story together from how the circuits are laid out.

 

I see what you mean.

 

Today's update:
I'm leaning more and more to the ignition control module. When I crank the engine I get no RPM reading on the tach and the manual said that was one symptom of a bad ICM. Also I measured the resistance of the coil and the values were per spec.

So I have the distributor off and I plan to replace the ICM, and for routine maintenace, the distributor cap and spark plug wires this weekend. Anything else?

P.S. I wish this section of the manual would have said to get the 8P connector off, it has to come off the bracket first... I worked probably 30 min before I figured it out.

 

You never mentioned if the blk/yel wire that powers the coil has 12V when the key is turned to the II position?

A coil can have the proper resistance readings and still be bad.

 

Yes, please check that out.

Bad resistance is one way for a coil to fail, that can be measured with normal meters.

Short to ground can happen only under high voltage, & it can't always be measured by normal meters.

 

Hi, checked the blk/yel wired in the to the ICM with the key on and it was 12V. Also checked the grn wired coming through the coil and it was 12v as well. There's a wire that goes to the tach and one to the ECM that it wasn't clear what to check, but other that that, things are pointing to the ICM.

I'll let you know how things go with a new ICM.

Thanks.

 

One way to check the ignitor is to hook up a 12V test light across the two leads going to the coil. You basically take the coil out of the circuit. The light should be off when the car is not running and the key is in the II position. The light will flash when trying to start if the ignitor is working properly.

 

Well, purchased new distributor cap, rotor, ignition control module, and spark plug wires and installed them this morning. The car now fires like its trying to start and I get some tach movement occasionally, but doesn't start. I've tried to twist the distibutor to the max in both directions with the same results. Is it possible to be 1 rev out of phase (TDC exhaust instead of TDC compression) and the engine still fire? Will the distributor keying allow me to put it on wrong?

Thanks.