This how-to covers DRBIII scan tool calibration for speedometers on 1998-2006 Dodge Ram trucks—plus many Jeep models of this era!
For the OBD-1 and OBD-2 diagnostics era, the Chrysler DRBIII™ scan tool is the ultimate calibration and diagnostic scan tool. While StarScan™ and TechConnect™ have become more recent tools, a DRBIII scanner is optimal for servicing 1987-2006 Jeep and Dodge Ram trucks!
American Axle & Manufacturing (“AAM”) builds OEM axles for popular trucks like the 2003-up Dodge Ram. Our ’05 Ram 3500 4WD came with an AAM 11.5″ (“Corporate”) rear axle and an AAM 9.25″ front axle. The tone ring, sandwiched between the ring gear and differential case, is the signal for the ABS sensor and speedometer.
At the upper left of the differential housing cavity, in line with the tone ring, is the ABS and speed signal sensor. The sensor sends a signal to the ABS module and PCM. The speedometer and powertrain functions depend upon an accurately calibrated speed signal.
35″ diameter tires and a change to 4.56:1 axle gearing altered the speedometer calibration. The Ram’s “makeover” and 4.56:1 ring-and-pinion sets now make the Dodge Ram a better trailer puller.
The DRBIII scan tool enables speedometer calibration on 1998-2006 Chrysler vehicles. For models with a tone ring ABS sensor, the calibration involves changes in tire revolutions per mile. (See the HD video how-to for details.)
