DTC 42

Code 42:

CIRCUIT DESCRIPTION:

The ECM provides a 12.0 volt signal to the Vehicle Speed Sensor (VSS). The VSS will toggle the signal low indicating the vehicle is moving. Code 42 will set if the signal line stays "High" or "Low" for 4 seconds or more.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. If speedometer does not work, it could be the cause of Code 42.

2. The ECM supplies 12 volts to the VSS.

3. The vehicle speed sensor on the back of the instrument panel will toggle the 12 volts supplied by the ECM.

DIAGNOSTIC AIDS:

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect ECM harness connectors for backed out terminals, improper mating, broken locks, improperly formed, or damaged terminals, poor terminal to wire connection and damaged harness. If no trouble is found, and Code 42 resets, replace ECM.

NOTE: An open vacuum line can cause a Code 42 to set. A careful visual inspection for air leaks should be made if vehicle speed signal circuit checks out okay.