Powertrain Controls - ECM/PCM

Diagnostic Chart:

Diagnostic Chart (Cont'd):

Circuit Schematic:

VSS CIRCUIT-NO SIGNAL
Vehicle speed values are provided by the vehicle speed sensor (VSS). The sensor is a permanent magnet (PM) variable reluctance sensor (VRS) mounted on the differential area of the transaxle converter housing. The PM generator produces a pulsing voltage whenever vehicle speed is above 5 km/h (3 mph). These pulses occur 16 times per each revolution of the differential housing and are translated to provide vehicle speed in mites per hour.

DTC PARAMETERS

DTC 24 will set if:
^ The VSS indication is less than 1.6 km/h (1 mph).
^ The engine speed is above idle. The MAP indication is less than 0.5 V for greater than 5 sec.
^ Vehicle not in park/neutral (Automatic Transaxle).

DIAGNOSTIC AIDS
When attempting to diagnose an intermittent problem, use the Scan tool[1] to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem.

Intermittents or opens suspected to be at the connector can be detected by using Diagnostic Service Probe. Voltage can be read on wires without disconnecting any connectors.

Check the tightness of the female terminal grip with a spare male terminal.

^ The speedometers wilt not work if the VSS subsystem has failed.
^ If VSS reading is accurate and speedometer is incorrect, problem is with instrument cluster.
^ VSS resistance 700-900 ohms.
^ If problem is intermittent wiggle wires while monitoring VSS signal on Scan tool and watch for signal to jump or for loss of signal.
^ The PCM will substitute VSS based on rpm if DTC 24 is set.

[1]Select Malfunction History from Scan tool Engine Control (EC) menu.