DTC 24

Fig. 034 Code 24 Vehicle Speed Sensor (VSS):

Fig. 035c Code 24 Vehicle Speed Sensor (VSS):

CODE 24

VEHICLE SPEED SENSOR (VSS)

CIRCUIT FAULT

2.0L (VIN 1)

FUEL INJECTION (TBI)


Circuit Description: The ECM applies and monitors 12 volts on CKT 437. CKT 437 connects to the Vehicle Speed Sensor which alternately grounds CKT 437 when drive wheel are turning. This pulsing action takes place about 2000 times per mile and the ECM will calculate vehicle speed based on the time between "pulses".
"Scan" reading should closely match with speedometer reading with drive wheels turning.
To prevent misdiagnosis, the technician should review Electrical Wiring Diagrams and identify the type of Vehicle Speed Sensor used to prior to using this chart. Disregard a Code 24 set when drive wheels are not turning.

Test Description: Numbers below refer to circled numbers on Diagnostic Charts.

1. Code 24 will set if vehicle speed equals 0 mph when:
Engine speed is between 1100 and 4400 rpm.
TPS is less than 2%
Low load condition, low MAP voltage, high manifold vacuum.
Not in Park or Neutral.
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.
2. 8-12 volts, at the I.P. connector, indicates CKT 4-37 is open between the I.P. connector and the VSS, or there is a faulty Vehicle Speed Sensor. A voltage of less than 1 volt, at the I.P. connector, indicates that CKT 437 wire is shorted to ground. If, after disconnecting CKT 437 at the Vehicle Speed Sensor, the voltage reads above 10 volts, the Vehicle Speed Sensor is faulty. If voltage remains less than 8 volts, then CKT 437 wire is grounded. If 437 is not grounded, there is a faulty connection at the ECM, or a faulty ECM.

Diagnostic Aids:

"Scan" should indicate a vehicle speed whenever the drive wheels are turning greater than 3 mph.
A faulty or misadjusted Park/neutral switch can result in a false Code 24. Use a "Scan" and check for proper signal, while in drive. Refer to CHART C-1A P/N switch check.
If Code 24 is intermittent, refer to DIAGNOSIS BY SYMPTOM.