View Full Version : CASE Learn
04-21-2013, 09:44 AM
Here's the story, I purchased a grand am from a co-worker. The car had a blown head gasket which I knew I could fix and have a grand am again for next to nothing. All fixed and running but I had a P0336 (Crank sensor error), I checked the wiring on the 7x sensor and as much of the 24x sensor I could without pulling the crank pulley. At this point, I have changed the 7x sensor on the back of the block and ensured the wiring is not touching any hot surfaces or running near any plug wires that could interrupt the signal. The code came back on the second start up after clearing the code, so should I pull the crank pulley and replace the sensor and inspect the wiring or get the car to a dealer to perform the CASE learn procedure? I just want to be efficient with my decisions so I don't waste time and money.
04-21-2013, 01:45 PM
According to my manual, that code is only for the 24x sensor behind the crank pulley. Doesn't have anything to do with the 7x sensor on the back of the engine. It only uses the 24x signal to improve idle spark control at speeds less than 1600 rpm. Above that is uses the 3x reference signal generated by the ignition control module (ICM) based off the 7x sensor. If there is a problem with the 24x signal, the engine will continue to run and use only the 3x reference signal and the cam position sensor signal to control fuel injector and ignition timing.
The manual says conditions for setting the DTC P0336 is that the ratio of 24x reference pulses to 3x reference pulses received by the PCM is incorrect. The CASE learn only applies to timing of the signal, and not the number of pulses, so I would assume that doing a CASE learn will not fix your problem. You'll probably need to inspect all the wiring and connections for the 24x sensor, and possibly pull the crank pulley and replace the sensor. It's not unheard of for them to go bad eventually. I would do this first before getting a CASE learn done, because if you pull the crank pulley and change the sensor you'll have to get one done anyway. No sense in doing it twice.
04-21-2013, 06:31 PM
I spent the day pulling the crank pulley and replacing the 24x sensor. I made sure to run the wires as they were before and I have now re-installed the pulley. First start up was great and runs perfectly. Let it warm up and go through the RPM range with no problems. Upon second start the SES comes on and the code is still P0336. I'm lost if I have replaced both sensors and wiring. Is it possible for the ignition control module to be faulty without throwing any other codes or misfires?
04-21-2013, 06:34 PM
It's possible yes. Typically it is wiring or the sensor though. It could be an intermittent fault from a bad wire. They get brittle over time. Try using a multi-tester to check for continuity on the wires from the sensor to the ICM, and wiggle the wires around to see if the signal goes out or not. That will indicate a break in the wire. If that's not it, might want to think about replacing the ICM. They are more $, but you can find used ones if needed.
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