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Home >> Dodge and Ram >> 2009 >> Durango Base, 3.7 K >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 14 (Powertrain Control Module (Pcm) - Electrical Diagnostics - 545RFE) >> DTC Troubleshooting >> P0720-Output Speed Sensor Circuit >> Theory Of Operation
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Theory Of Operation

WARNING: This page is about a different variant/trim than selected.

The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore, the integrity of this data is verified through the following checks:

  1. When in gear, if the gear ratio does not compare to a known gear ratio, the corresponding in-gear trouble code is set (DTCs P0731-36, P1736 and P1776).
  2. An excessive change in input or output speeds indicating signal intermittent which will result in the DTCs P0716 and/or P0721 being set.
  3. If the common speed sensor ground circuit is lost, both sensor inputs will read the signal from the input speed sensor at idle in neutral. Since the input speed sensor has 60 teeth and the output speed sensor has 30 teeth, this results in an apparent speed ratio of 1:2 and may cause the DTC P1794 to set.
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