I guess I'm to late to the party. I was about to suggest a bad CKP signal. Sometimes it's not even the CKP sensor itself, but a short to ground in either the sensor or module. If there is a short to ground, then there may actually be a signal being sent despite not seeing it. When techs, or DIY'ers, check it they often are using a scale that won't pick it up. If there is a short to ground the signal is there, but just really low voltage due to the short.