Test B4 - Vane Air Temperature (Vat) Sensor

Fig 1: VAT Circuits

CIRCUIT PIN IDENTIFICATION

Circuit	Breakout Box Pin	ECA Pin
2.2L MTX Non-Turbo
VAT	45	2K
SIGRTN	46, 49	2D
2.2L Except MTX Non-Turbo
VAT	45	2P
SIGRTN	46, 49	3D

NOTE: Enter this test only when a Code 10 is displayed during the QUICK TEST procedure or when directed here from another CIRCUIT TEST. Ambient temperature must be greater than 50°F (10°C) for this test.

1) Checking System Integrity Visually check all wiring, harnesses, connectors and components for evidence of damage, overheating, shorting or looseness. If a fault is found, repair as necessary. If no faults are found, go to next step.

2) Checking VAT Voltage Ensure engine is at operating temperature. With key off, install breakout box. Turn ignition on. Locate VAT sensor in VAF meter. Measure voltage between VAT and SIGRTN test pins. Compare voltage to specifications shown in VAT SENSOR VOLTAGE SPECIFICATIONS . If voltage is within specification, VAT circuit is okay. Fault is in another circuit or ECA. If voltage is not within specification, go to step 3.

VAT SENSOR VOLTAGE SPECIFICATIONS

Temperature °F (°C)

⁽¹⁾ Volts

20 (-6)

3.64

30 (-1)

3.36

40 (4)

3.05

44 (7)

2.79

50 (10)

2.29

60 (16)

2.61

70 (21)

2.35

80 (27)

2.05

90 (32)

1.76

100 (38)

1.57

⁽¹⁾	Values may vary by 15 percent.

3) Checking VAT Resistance - Ensure engine is at operating temperature. With ignition off and breakout box installed, measure resistance between VAT and SIGRTN test pins. Compare resistance to specifications shown in VAT SENSOR RESISTANCE SPECIFICATIONS . If resistance is within specification, go to step 4. If resistance is not to specification, go to step 5.

VAT SENSOR RESISTANCE SPECIFICATIONS

Temperature °F (°C)	Ohms
-4 (-23)	15,000
32 (0)	5210
68 (20)	2500
104 (40)	1100
140 (60)	600
176 (80)	300

4) VAT Circuit Isolation With breakout box installed, leave ECA disconnected. Remove VAF meter connector. Measure resistance between VAT and SIGRTN test pins. If resistance is less than 5 ohms, repair VAT sensor circuit to VAF meter. If resistance is more than 5 ohms, replace ECA.

5) VAT Sensor Resistance Disconnect VAF meter connector. Locate VAT sensor in VAF meter. With key off, measure sensor resistance. Compare resistance to specifications shown in VAT SENSOR RESISTANCE SPECIFICATIONS . If resistance is okay, repair circuit between VAT sensor and ECA. If resistance is not to specification, replace VAT sensor.