does anyone know of a way to test this without an oscilloscope? from what i understand, the ignition amp sends a series of high frequency pulses to teh coil. im trying to make sure my coil is getting the right signal from the amp before finally condemming the coil. im hesitant to do this because everything i read says the coils almost never fail.

thanks!

Not sure about the rest, But it is rare for a coil to go out. I have a saying.
Coils don't go out. I sold auto parts for 6 years. In my six years, I think I sold 200 ignition coils. I kept tabs when customers would return, and of those 200 coils I sold, maybe only 3 needed replacement. I stand by my first quote, Coils don't go out.

Corey

Louisiana.

when i swap out the coil with a different one, it starts. i didn't want to believe it, but im think my case is one of those minority cases. i guess someone has to be the 1% of cases where the coil is bad. the reason i was asking about testing this input signal into the coil was so i could know for sure. despite the fact that replacing the coil seems to make it work, im still skeptical.

Do you have a no start with no spark? While cranking you should see the tach bounce a bit. This indicates you have an output from the amp because the tach signal comes off right at the coil negative. The ignition amp is more likely to fail than the coil. You can induce the coil to fire by disconnecting the negative wire. Take another short wire and ground the coil negative terminal for just an instant. The coil should fire when you do this.
--
David Hunter

Most 240's have no tach, so that's sometimes a hard thing to check that way.
For this car, I'd suspect the crank sensor (rpm sensor) before I'd suspect the coil or power stage. The power stage is not necessarily innocent though and I think I would look for a spare...
--
Rob Bareiss, New London CT ::: '87 244DL/M47- 221K, 88 744GLE- 202K, 91 244 181K, 88 244GL 145K

I've just had the power amplifier on my 93 diagnosed as faulty. Apparently they are known to be sensitive, and can partly fail when cold, damp etc. All I did was remove it, separate from its heat sink, clean off all the corrosion and refit. It works perfectly now. I was advised always to carry a working spare.
Crank sensors too break down with age. Measure the resistance between the centre pin and one of the others - only one will give a reading. I can't remember what the limits are, but my 167 Ohms is apparently fine.

Where is the power stage on this car?

if it was the crank position sensor, wouldn't the ICU throw a code for it? the ICU is throwing no codes. i have replaced the coil with a known good one and it works, however, during my troubleshooting, i could have isolated the coil faster if i knew how to test the input from the power stage. are the ICU diagnostics not reliable for a faulty CPS?