DTC 24

Code 24:

CIRCUIT DESCRIPTION:

The Manifold Air Temperature (MAT) Sensor uses a thermistor to control the signal voltage at the ECM. The ECM applies a voltage (4-6 volts) to the sensor. When the air is cold, the sensor (thermistor) resistance is high, therefore, the ECM will see a high signal voltage. If the air is warm, the sensor resistance is low, therefore, the ECM will see a low voltage.

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

1. Verifies that 4-5 volts is present at the MAT sensor connector.

2. This test checks the ground side of the MAT sensor circuit.

3. This test determines if the problem is caused by an open circuit or the ECM.

4. This test determines if the YELLOW/BLACK wire is open or the ECM is defective.

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 "THA," "E2" or "E21" improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.