Do you have the old Opti?
Are you 100% sure we're looking at the low res pulse? Here are two pictures of the wheel, look at the high res (outer) and low res (inner) slots in the wheel. The outer pattern would give a square wave. The inner would be much different.no i had that done in a shop about 6 years ago, keep in mind it has been not working correctly for the last 3 years. Back then i was new to the lt1 engine so when i ran it through a car wash and dried the car, after it would turn over but not start and i had to have it towed to the chevy garage.
The thing they call the ICM is a version of a regular HEI module. My 95 has a MSD 6AL, I home made a driver to replace the ICM. At least your wave forms make sense now.Well I finally found on this site where someone was explaining where to hook the oscilloscope up to the car and its not where I was hooking it from what I understand. I was hooking it up at the pin b wire on the icm side of the engine and I need to hook it up directly to the wires that come out of the opti and go to the pcm on the other side of the engine with the wires that sit on the intake manifold. One wire carries the low res signal to the pcm and another on the same harness carries the high resolution signal. The wire I was testing comes from the pcm after it has already looked at those signals and tells the icm when to fire the coil through the opti to the spark plug wires. So I will do this tomorrow and go from there.
You measure Ohms with a meter. I assumed you had one.The only things I have tested with the scope so far is an AA battery and the 2 places on the car but they are both low volt wires, I think both wires are at 5 volts dc maximum. That scope doesn't seem to measure ohms, the only options are ac, dc, and ground. The scope will still measure positive volts from an AA battery so I'm assuming that it isn't shorted out but I am no expert when it comes to oscilloscopes to say the least.
Scope died. Explains your "no start" problem. Did it come with a schematic?when I test the scope for ohms with the multimeter it reads a steady 9.4 ohms and there is no reaction on the screen of the scope when I make connection for the test. When I test ohms on myself the meter reads between 5600 and 6000 so that seems like its reading fine, but is just a little over 9 ohms when testing the scope sound like to low of a number?