Originally Posted by 04 EDGE
and the rear ABS sensor is also the speedo sensor there is no seperate sensor for the rear, whoever told you that dosent know what there talking about.
The source of the raw vehicle speed pulse varies by year:
98~2000 use the same diff housing sensor for the rear axle ABS and for the raw VSS pulse. Speedometer correction for tire size is done in the GEM for RABS or in the 4WABS Module for 4WABS.
2001~current have the rear diff ABS sensor but there is a separate Output Shaft Speed sensor on the transmission that supplies the raw vehicle speed pulse to the PCM. The OSS reads a tooth wheel on the output shaft. Speedometer correction for tire size and axle ratio is done in the PCM.
95?~97 also have the rear axle ABS sensor but use a gear driven VSS signal generator on the trans or transfer case. Speedometer correction for tire size and axle ratio is done by interchangeable gears similar to a speedometer cable.
RABS trucks use only the single diff housing ABS sensor. 4WABS adds individual sensors at each front wheel. All Rangers have had standard 4WABS since 2001.