Transaxle Control System

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

DTC 31 will set if the following conditions are met:
^ The TCM sees a drive range signal ("R," "D," "2" or "L") from the Park/Neutral Position (PNP) switch, an engine speed higher than 2,000 rpm, and no vehicle speed input from the vehicle speed sensor (VSS).

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Checks for a vehicle speed signal at the TCM connector C2.
2. Checks for a vehicle speed signal at the VSS connector.
3. Checks for an open in the PPL wire between TCM connector C2 and the VSS connector.
4. Checks for an open in the LT GRN wire between TCM connector C2 and the VSS connector.
5. Checks for a short to ground in the LT ORN wire between TCM connector C2 and the VSS connector.

DIAGNOSTIC AIDS
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Inspect the TCM hamess 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) shielding and shield ground for breaks, cuts or opens.