P0720

Diagnostic Chart:

Description:

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.

Conditions for Setting the DTC

^ No VSS (Transaxle) signal inputted while vehicle is running in Drive (D) or Second (2) range.

^ 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 the following conditions:

^ Open or shorted VSS (Transaxle).

^ Faulty electrical circuits between the VSS (Transaxle) and the PCM.

^ Faulty PCM.

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.

Inspect the PCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and for poor terminal-to-wire connections.

If this DTC cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.

If any wiring repairs need to be made, refer to Repair Procedures in Electrical Diagrams.

DTC Confirmation Procedure

1. Turn ignition switch to LOCK.

2. Connect scan tool to Data Link Connector (DLC).

3. Turn ignition switch to ON.

4. Clear DTC, pending DTC and freeze frame data in PCM memory by using scan tool.

5. Start engine.

6. Drive vehicle to at least 40 Km/h (25 mph) in Drive (D) range for at least 10 seconds.

7. Stop vehicle.

8. Check for pending DTC with scan tool.

Test Description

Numbers below refer to circled numbers 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. Checks internal resistance of the VSS.

3. Checks for a faulty VSS (Transaxle).

4. Checks for an open in LT ORN wire.

5. Checks for an open in PPL wire.

6. Check for faulty PCM.

7. Checks voltage output of the VSS (Transaxle).