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OK everybody I am having a problem with my spark. So a couple days after I bought the vehicle I watched it and I went and drove it and I press the gas pedal and it hesitated then shut off a couple seconds later and had to get it towed to a shop. They ran the codes it was a P0335 and a PO336 code which is the crankshaft position sensor. I replaced the crankshaft position sensor and the ignition control module sensor or known as the ICM. I have checked spark plugs, fuses, wires, everything . When I replaced The crankshaft position sensor the codes went away. Still crank no start so I bought a 12 volt test light. I have tested a couple things and the light comes on and I have tested some things where the light is off. I think the OPTi spark or the coil might be bad but can someone please help me. It has the Lt1 5.7 v8. 96 Pontiac firebird trans am
 

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Hate to tell you this, but on 96 & 97 lt1 motors, the crank sensor is for misfire detection only. Since you replaced icm, hopefully it's good. Time to start considering the opti as the weak link in system.

To 100% test the low & high resolution pulses coming from opti, you need an oscilloscope to test low & high res pulses to make sure they're the proper square wave signal.

Shoebox site has a simple test to show low & high res signals are being sent out. But the test only shows that pulses are present. If pulses are not the correct square wave, eng

If pulses are dropping out or changing the wave form pcm will not recognize the signal and cut off spark. And when checking codes, if both low & high res pulses are missing, no opti code will set .

Good news on the oscilloscope, you can buy a PC based scope for around $70, on ebay, amazon, etc. And if opti is bad, only replace with a GM, Delco, or Delphi opti. The rest are junk.

Does your security light come on when key is turned to on> Then go out after several seconds. This means that security system is in normal function. If light doesn't turn off, or doesn't light at all, there's a good chance that security system is keeping ignition system from working.
 
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