Powertrain Controls - ECM/PCM

Code Chart 24:

Transaxle ECU Circuit:

CIRCUIT DESCRIPTION:

The Vehicle Speed Sensor (VSS), which is located in the instrument panel is a reed switch type. The ECM provides battery voltage to the switch which will toggle the voltage high and low. This pulsed signal to the ECM is used by the ECM to determine mph/kPh.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. Code 24 will set if vehicle speed equals 0 mph when:

^ Engine speed is between 1500 and 4400 rpm.
^ Vehicle speed is indicated less than 5 kPh (3 mph).
^ No malfunction Code 33 set.
^ MAP sensor is less than 43 kPa.
^ Not in Park or Neutral (A/T).
^ All conditions met for 5 seconds.
These conditions are met during a road load deceleration. Disregard Code 24 that sets when drive wheels are not turning.

DIAGNOSTIC AIDS:

An open in the ECM circuit will result in 4-5 volts at terminal "C5" of the instrument panel connector. This voltage is sourced from the transaxle ECU for 4 speed transaxle only.

Scan should indicate a vehicle speed whenever the drive wheels are turning greater than 3 mph. Check the WHT wire for proper connection to be sure they are clean and tight and the harness is routed correctly. Testing and Inspection (A/T) A faulty or misadjusted Park/Neutral switch can result in a false Code 24. Use a Scan tool and check for proper signal while in drive. For P/N switch check, refer to Chart C-1A. Chart C-1A Park/Neutral Switch Diagnosis