E024

Code E024 - Vehicle Speed Sensor (VSS) Circuit:

Wiring Diagram for Code E024 - Vehicle Speed Sensor (VSS) Circuit:

CODE E024 - VEHICLE SPEED SENSOR (VSS) CIRCUIT

Circuit Description:

The VSS system incorporates three major components; the vehicle speed generator, the BCM, and the ECM. The vehicle speed sensor is a permanent magnet generator assembly attached to the transaxle. As the vehicle moves, the generator creates a "sine wave" electrical pulse which is monitored by the BCM. In the BCM, this is amplified and "cleaned up" via the same process used in a buffer. Part of this "cleaning up" involves changing the "sine wave" signal to "a square wave" or on/off type signal. By determining the length of time between the "ON" and "OFF" portions of this signal, the BCM can interpret the vehicle speed. It then transmits this data via CKT 437 to the ECM.

Because of the circuitry involved, it is highly unlikely that a Code E024 alone will be caused by a faulty VSS. However, a combination of Codes E024 and B124 could indicate this. In the case of a Code B124 accompanying a Code E024, see the appropriate charts in the BCM section first.

To set a Code E024, the following conditions must exist:

a. Engine running between 1500 and 4000 RPM.
b. Codes E033 or E034 not present.
c. LV8 reading (Diagnostics Data ED23) between 40 and 150 counts.
d. Vehicle speed less than 3 MPH.
e. Gear selector not in park or neutral.
f. Above conditions for 40 seconds.




Test Description: The following numbered steps correspond with the step numbers on the diagnostic chart.

1. If a Code B124 is present also, refer to the appropriate chart for diagnosis of B124 before attempting to diagnose E024.

2. If ECM Data ED12 (Vehicle Speed) displays "O" MPH, the ECM is not receiving a VSS input from the BCM.

3. A "O" MPH display at this point, indicates a fault which should have set a Code B124. Refer to that chart for the remainder of diagnosis. A display greater than "O" indicates a fault in CKT 237, the connections at the ECM or BCM, or a faulty ECM.




Diagnostic Aids:

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.

Check for:

a. Poor Connection or Damaged Harness - Inspect ECM harness connector terminal "A10" and BCM connector terminal "3C4" for improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

b. Intermittent Test - If connections and harness checks out ok, raise front wheels, block rear wheels, idle engine in low gear and monitor ED12 (Vehicle Speed) display while moving related connectors and wiring harness. If the failure is induced, the "Vehicle Speed" display will abruptly change. This will help to isolate the location of the malfunction.