Circuit Test Vat - Vane Air Temperature

Fig 1: VAT Sensor Circuit & Connector Terminal ID

CIRCUIT PIN IDENTIFICATION

Circuit	Breakout Box Pin No.	ECA Pin	Wire Color
1.8L
VAT	45	2P	Red/Black
SIGRTN	46 & 49	2D	Black
2.2L
Non-Turbo M/T
VAT	45	2P	Red
SIGRTN	46 & 49	2D	Green/Yellow
All Others
VAT	45	2K	Red
SIGRTN	46 & 49	3D	Green/Yellow

NOTE: Enter this test only when a Code 10 is displayed during self-test procedures (KOEO or KOER), 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, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to next step.

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

NOTE: If using hot air gun to heat sensor, avoid overheating plastic or rubber components.

VOLTAGE SPECIFICATIONS (VAT SENSOR)

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 RESISTANCE SPECIFICATIONS (VAT SENSOR) . If resistance is within specification, go to next step. If resistance is not as specified, go to step 5).

RESISTANCE SPECIFICATIONS (VAT)

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 all other test pins. If any 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 ignition off, measure resistance between VAT terminal and SIGRTN terminal of VAF meter. Compare resistance to specifications shown in RESISTANCE SPECIFICATIONS (VAT SENSOR) . If resistance is as specified, repair VAT and/or SIGRTN circuit between VAF meter and ECA. If resistance is not as specified, replace VAF meter.