DTC 24

Diagnostic Chart





Circuit Diagram

Circuit Description
Vehicle speed information is provided to the engine control module by the vehicle speed sensor, which alternately grounds the WHT wire located in the meter panel when the drive wheels are turning. This pulsing action takes place 4096 times per mile, and the engine control module will calculate vehicle speed based on the time between "pulses".

Test Description
The number(s) below refer to the circled number(s) on the diagnostic chart.
1. Diagnostic trouble code 24 will set if vehicle speed equals 0 miles per hour when:
- Engine speed is between 1600 and 1825 revolution per minute.
- Vehicle speed is indicated less than 1 Km/H (0.6 miles per hour).
- Manifold absolute pressure reading below 20.7 kPa.
- Low speed condition (low manifold absolute pressure voltage, high manifold vacuum)
- Not in park or neutral. (Automatic Transmission.
- All conditions are met simultaneously for 1.5 seconds.
- No diagnostic trouble code 33 is set.

NOTE: These conditions are met during a road load deceleration. Disregard diagnostic trouble code 24 that sets when drive wheels are not turning.

Diagnostic Aids
- A "Scan tool" should indicate a vehicle speed whenever the drive wheels are turning greater than 0.6 mile per hour. Check the WHT wire for proper connections to be sure they are clean and tight and the harness is routed correctly.
- Refer to intermittents in DIAGNOSIS BY SYMPTOM.
- (A/T) A faulty or misadjusted park/neutral position switch can result in a false diagnostic trouble code 24. Use a "Scan Tool" and check for proper signal while in "DRIVE".