Jim Grant's Tech Tips

'97 Pontiac Grand AM, A-lot of Parts and Computer Code

Q: My ’97 Pontiac Grand AM has a computer code #1336 that has been down loaded in the last 6 months. I have changed the oxygen sensor, crankshaft position sensor, PCM, plugs, ignition cap assembly, catalytic converter, air filter, thermostat, temperature sensor for the coolant and the engine light is still on. So do you have any recommendations?

- Fred Z.

A: Your vehicle’s computer is only telling you that it wants to learn something. Diagnostic Trouble Code (DTC) # P1336 simply means that the computer has not learned and recorded the variations in crankshaft of the engine. The crankshaft in your vehicle’s engine has a wheel with notches that corresponds with piston position. The crankshaft position sensor reports to the computer each time one of the notches passes by the sensor. After all the computer needs to know where the piston is so it can add fuel or create spark at the spark plug at the right time. But the computer needs to take this knowledge of crankshaft position to the next level. It needs to know and record any variations. Engines and computer sensors are mass-produced and, in theory, all of these parts should be identical. But it is not the case and the engineers allowed for this in the software of the computer. Once in your vehicle’s lifetime the computer needs to learn crankshaft variations and this is performed at the factory. This lifetime information is fine unless the crankshaft position sensor is disturbed (unbolted), replaced or if the vehicle computer is replaced. You’ve done both! The check engine light will not turn off until the computer is commanded to perform a Crankshaft Position Sensor Variation Learning Procedure. To perform this step requires a computer scan tool to access the learn command mode of the software. A little class time should be all that is needed to turn your check engine light off.