Important Safety Notice

Appropriate repair methods and procedures are essential for the safe, reliable operation of all motor vehicles, as well as the personal safety of the individual doing the work. This article provides general directions for repairing vehicles with tested, effective techniques. Following them will help ensure reliability. There are numerous variations in procedures, techniques, tools, and parts for repairing vehicles, as well as in the skill of the individual doing the work. This article cannot possibly anticipate all such variations and provide advice or cautions as to each. Accordingly, anyone who departs from the instructions provided in this article must first establish that they compromise neither their personal safety nor the vehicle integrity by their choice of methods, tools, or parts.

This pinpoint test is intended to diagnose the following:

• Integrated mass air flow (MAF)/intake air temperature (IAT) sensor (12B579).
• Harness circuits IAT, VREF, and SIGRTN.
• Powertrain control module (PCM) (12A650).

Voltage values calculated for VREF = 5 volts. These values can vary by 15% due to sensor and VREF variations.

Fig 1: IAT Temperature/Voltage Graph

Courtesy of FORD MOTOR CO.

Fig 2: Identifying Mass Air Flow/Intake Air Temperature (MAF/IAT) Sensor Connector

Courtesy of FORD MOTOR CO.

Fig 3: Identifying Powertrain Control Module (PCM) Connector

Courtesy of FORD MOTOR CO.