DTC 24

DIAGNOSTIC CHART





WIRING DIAGRAM

INSPECTION PROCEDURE

Circuit Description:
The Engine Control Module (ECM) applies and monitors 12 volts on CKT A10. CKT A10 connects to the vehicle speed sensor which alternately grounds CKT A10 when drive wheels 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. Disregard a Code 24 set when drive wheels are not turning.

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. DTC 24 will set if vehicle speed equals 2 mph when:
- Engine speed is greater than 1400 rpm
- TPS is less than 5% (closed throttle)
- Low load condition (high vacuum). Less than 25 kPa.
- 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:
"Scan" should indicate a vehicle speed whenever the drive wheels are turning.
If all OK, refer to "Intermittents" in "Symptoms".