P0720

Output Speed Sensor Circuit:

Circuit Description:

The Powertrain Control Module (PCM) receives an AC voltage input from the Vehicle Speed Sensor (VSS) (Transaxle) whenever the drive wheels are rotating. Because the frequency of the AC voltage signal increases with wheel speed, the PCM can calculate vehicle speed from the frequency of the AC signal. The PCM uses this information to determine shift points.

DTC Detecting Condition:

DTC P072O will set if the following conditions is met: No Vehicle Speed Sensor (VSS) (Transaxle) signal inputted while vehicle is running in D" or "2" range.

DTC Chart Test Description

Numbers below refer to circled numbers on the diagnostic chart.

1. Checks for proper resistance values.
2. Checks for a faulty VSS (Transaxle).
3. Checks for an open in LT GRN wire.
4. Checks for an open in PPL wire.
5. Determines whether this condition is intermittent and not due to a faulty PCM.
6. Checks for proper voltage output of the VSS (Transaxle).

Diagnostic Aids:

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Inspect the Powertrain Control Module (PCM) harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and for poor terminal-to-wire connections. In addition, carefully check the Vehicle Speed Sensor (VSS) (Transaxle) shielding and shield ground for breaks, cuts or opens.