P0720

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 in order to determine shift points.

Conditions for Setting the DTC
DTC P0720 will set if the following conditions are met:
^ No VSS (Transaxle) signal is inputted while the vehicle is running in Drive (D) or Second (2).
^ One driving cycle detection logic.

Action Taken When the DTC Sets
A DTC P0720 is stored and the Malfunction Indicator Lamp (MIL) is turned ON.

Diagnostic Aids
Check for the following conditions:
^ Open or shorted VSS (Transaxle)
^ Faulty electrical circuits between the VSS (Transaxle) and the PCM
^ A faulty PCM
An intermittent may be caused by the following conditions:a poor connection, rubbed through wire insulation or a wire broken inside the insulation.
^ A poor connection
^ Rubbed through wire insulation
^ A broken wire inside the insulation
Inspect the PCM harness connectors for the following conditions:
^ Backed out terminals
^ Improper mating
^ Broken locks
^ Improperly formed of damaged terminals
^ Poor terminal-to-wire connections
Perform the following steps if DTC P0720 cannot be duplicated:
1. Read the information in the freeze frame data.
2. Use the data to determine the vehicle operating conditions when the DTC was set.
Inspect the wiring. If any wiring repairs are necessary, refer to Diagrams.

DTC Confirmation Procedure
1. Turn the ignition switch to LOCK.
2. Connect the scan tool to Data Link Connector (DLC).
3. Turn the ignition switch to ON.
4. Use the scan tool to clear the following items from the PCM memory:
^ The DTC
^ The pending DTC
^ The freeze frame data
5. Start the engine.
6. Operate the vehicle in Drive (D). Obtain a speed of at least 40 km/h (25 mph) for at least 10 seconds.
7. Stop the vehicle.
8. Use the scan tool to inspect for DTC P0720.

Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
2. This step inspects for internal resistance of the VSS.
3. This step inspects for a faulty VSS (Transaxle).
4. This step inspects for an open in LT GRN wire.
5. This step inspects for an open in PPL wire.
6. This step inspects for a faulty PCM.
7. This step inspects the voltage output of the VSS (Transaxle).