2004 Buick Lesabre, 108k miles
Had code P0336 and rough idle in neutral, so I replaced the crank position sensor and oil seal.
The car started up and ran for 2 minutes then it just died. I heard a sound like a screw falling as it died, but found nothing.
I tried another new sensor and the original too. No start. No rpm signal while cranking.
With my multimter I determined a problem: the two signals wires (3x and 18x) have 6V coming from the Ignition Control Module with the sensor unplugged which is good. BUT with the new Acdelco sensor or with the original sensor plugged in, it drops to a constant 1.7V and 0.7V. The new and more expensive GM Genuine sensor reads 5.5V and 4.5V plugged in.
No reaction to reluctor ring at all. I replaced the connector with a brand new GM Genuine. Turned the engine by hand, tried it outside too putting metal betwwen the magnets. No reaction. Sensor power reads 11.7V, ground reads 4 milivolts I believe. I checked wires, cleaned ground for ICM.
New Ignition Control module did not solve it either. Same result, except the new module sends 5Volts unplugged and not 6Volts
Any ideas what is this? I checked fuses, tested ignition relays, nothing was bad.
Its a pull down design hall effect sensor. Above mentioned reference signals should remain 6V and pull to ground 0V as the reluctor ring passes. Therefore producing a square signal for further processing by the ICM and triggering the start up procedure.(spark at the right time and fuel).
Why is this not happening?
Do you have ECU communication? check it with a proper system-level scan tool - see what these sensors output. I suspect that something has seriously went wrong with the electronics - it really does sound like a major electronics fault that might have been caused by the new bad sensor...
Thank you for the response. I dont have a great scan tool unfortunately. Everything else seems to work fine electronically. All the live data shows while cranking, no troublecodes so its really strange. I'll try to find a mechanic and get it diagnosed. I cant figure this one out on my own.