I have a 2002 Elantra GLS and my speedometer started fluctuating and cruise control started acting up. the CEL has NOT kicked on. I replaced the input sensor with one from a salvage yard and it tripped the CEL and went into safety mode. Stuck the original back in and back to where I started. Got a new sensor, aftermarket, and it tripped the CEL, code 1527 and trans went into safety mode. removed and replaced with the original and I'm back to square one - fluctuating speedometer and cruise control and no CEL. As with other comments I have heard of the ABS sensor is still used in non ABS to read rpm. Could this possibly be the problem or am I headed in the wrong direction? I'm at a standstill right now. Any ideas out there?