DTC 24

Code 24 Diagnostic Chart:

Vehicle Speed Sensor Circuit Diagram:

CIRCUIT DESCRIPTION:
Vehicle speed information is provided to the PCM by the vehicle speed sensor, in the transaxle. The A/C voltage level and the number of pulses increases with vehicle speed. The PCM converts the pulsing voltage to mph, and the mph can be displayed with a scan tool. The function of the VSS buffer, used in past models years has been incorporated into the PCM. The PCM supplies the necessary signal for the instrument panel (4004 pulses per mile) for operating the speedometer and the odometer.

Code 24 will set if vehicle speed signal equals less than 3 mph when:
^ Engine is running
^ No Code 31
^ Transmission out of PARK or NEUTRAL for more than 4 seconds
^ Engine speed is greater than 3000 rpm
^ All conditions are met for 2 seconds

OR

^ Vehicle speed goes from grater than 18 to 0 mph in less than 2 seconds, brake not applied

NOTE: If code 24 is set, the PCM will allow 2nd or 3rd gear operation only.

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. The VSS signal generator only produces a signal if the drive wheels are turning greater than 3 mph.
2. Before replacing the PCM, check the Mem-Cal for correct application.

DIAGNOSTIC AIDS:
^ Scan should indicate a vehicle speed whenever the drive wheels are turning greater than 3 mph. Check circuit 400 and 401 for proper connections to be sure they are clean and tight and the harness is routed correctly.