Pinpoint Test DA: Intake Air Temperature (IAT) Sensor: Introduction

WARNING: TO PREVENT THE RISK OF HIGH-VOLTAGE SHOCK, ALWAYS FOLLOW PRECISELY ALL WARNINGS AND SERVICE INSTRUCTIONS, INCLUDING INSTRUCTIONS TO DEPOWER THE SYSTEM. THE HIGH-VOLTAGE HYBRID SYSTEM UTILIZES APPROXIMATELY 300 VOLTS DC, PROVIDED THROUGH HIGH-VOLTAGE CABLES TO ITS COMPONENTS AND MODULES. THE HIGH-VOLTAGE CABLES AND WIRING ARE IDENTIFIED BY ORANGE HARNESS TAPE OR ORANGE WIRE COVERING. ALL HIGH-VOLTAGE COMPONENTS ARE MARKED WITH HIGH-VOLTAGE WARNING LABELS WITH A HIGH-VOLTAGE SYMBOL. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN SERIOUS PERSONAL INJURY OR DEATH.

This pinpoint test is intended to diagnose the following:

integrated mass air flow (MAF)/intake air temperature (IAT) sensor (12B579)
harness circuits: IAT and SIGRTN
powertrain control module (PCM) (12A650)

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

Fig 1: Intake Air Temperature Sensor Temperature And Voltage Graph

Courtesy of FORD MOTOR CO.

TEMPERATURE SENSOR VOLTAGE AND RESISTANCE SPECIFICATIONS

Temperature		Temperature Sensor Values
°C	°F	Voltage	Resistance (K ohms)
120	248	0.28	1.18
110	230	0.36	1.55
100	212	0.47	2.07
90	194	0.61	2.80
80	176	0.80	3.84
70	158	1.05	5.37
60	140	1.37	7.70
50	122	1.77	10.97
40	104	2.23	16.15
30	86	2.74	24.27
20	68	3.26	37.30
10	50	3.73	58.75
0	32	4.14	95.85
-10	14	4.45	160.31

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

Courtesy of FORD MOTOR CO.

MAF/IAT CONNECTOR PIN REFERENCE CHART

Pin	Circuit
2	SIGRTN (Signal Return)
1	IAT (Intake Air Temperature)

Fig 3: Powertrain Control Module (PCM) Connector

Courtesy of FORD MOTOR CO.

PCM CONNECTOR PINS REFERENCE CHART

Pin	Circuit
B41	MAF RTN (Mass Air Flow Return)
B58	SIGRTN (Signal Return)
B47	IAT (Intake Air Temperature)