Diagnostic Aids
If CKP variation learn procedure cannot be learned, check for a chipped or damaged reluctor wheel, incorrect CKP sensor alignment to reluctor wheel, excessive crankshaft runout, interference in signal circuit to CKP sensor or incorrect ratio of crankshaft to camshaft pulses.
Engine misfire diagnostics are not available if engine speed is more than 1000 RPM and DTC P1336 is set.
If PCM receives an incorrect crankshaft to camshaft ratio, PCM will not allow scan tool to enable the learn procedure. When learn procedure is in progress and engine speed is at 4000 RPM, a decrease in engine speed will occur. During deceleration, PCM monitors CKP sensor signal and stores the pattern. The pattern is used to determine if crankshaft speed variations are due to engine misfire.
If problem is intermittent, go to INTERMITTENT TROUBLE CODE DETERMINATION under SELF-DIAGNOSTIC SYSTEM.