DTC 24

Code Chart 24:

VSS Circuit:

CIRCUIT DESCRIPTION:
Vehicle speed information is provided to the ECM by the Vehicle Speed Sensor (VSS), which is a Permanent Magnet (PM) generator and it is mounted in the transaxle. The PM generator produces a pulsing voltage whenever vehicle speed is over about 3 miles per hour. The AC voltage level and the number of pulses increases with vehicle speed. The ECM then converts the pulsing voltage to mph which is used for calculations and the mph can be displayed with a Tech 1 scan tool.

TEST DESCRIPTION: Number(s) below refer to circled number(s) on the diagnostic chart.

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

^ Engine speed is between 2200 and 4400 RPM.
^ TP sensor is less than 2%.
^ Low load condition.
^ Not in park or neutral.
^ All conditions met for 3 seconds.

These conditions are met during a road load deceleration. Disregard DTC 24 that sets when drive wheels are not turning.

^ The PM generator only produces a signal if drive wheels are turning greater than 3 mph.

DIAGNOSTIC AIDS:
A Tech 1 scan tool should indicate a vehicle speed whenever the drive wheels are turning greater than 3 mph.

A problem in CKT 389 will not affect the VSS input or the readings on a Tech 1 scan tool.

Check CKTs 400 and 401 for proper connections to be sure they're clean and tight and the harness is routed correctly. - Intermittent Malfunctions

(A/T) A faulty or misadjusted Park/Neutral Position (PNP) switch can result in a false DTC 24. Use a Tech 1 scan tool and check for proper signal while in drive. For PNP switch diagnosis Chart C-1A Park/Neutral Switch Diagnosis