Vane Airflow (VAF) Meter

Fig 1: VAF Meter Circuits

Courtesy of FORD MOTOR CO.

VAF CIRCUIT PIN IDENTIFICATION

Circuit	ECA Pin	BOB Pin	Wire Color
VAF	2O	45	W
SIGRTN	2D	46, 49	Bk
VREF	2K	39, 40, 44, 45	Bk/Y
GND	2A	45	Bk

NOTE: Enter this test only when a Code 08 is displayed during the QUICK TEST procedure or when directed here from another CIRCUIT TEST. To avoid unnecessary use of diagnostic time, check for unmetered air leaks between VAF meter and throttle body. This test is intended to diagnose only VAF and VREF circuits.

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 VAF Meter Voltage Install breakout box. Turn key on. Measure voltage between VAF and SIGRTN test pins. Voltage should be as listed in VAF METER VOLTAGE VALUES . If not, go to step 3. If voltage is correct, measure voltage between VREF and SIGRTN test pins. If voltage is 7-9 volts, circuit is okay. Fault is in another circuit or ECA. If voltage is not 7-9 volts, repair VREF circuit between ECA and VAF meter.

VAF METER VOLTAGE VALUES

Door Position	Volts
Fully Closed	.5-1.5
1/8 Open	.59
1/4 Open	1.19
3/8 Open	1.78
1/2 Open	2.38
5/8 Open	2.97
3/4 Open	3.56
7/8 Open	4.16
Full Open	4.5-5.0

3) Checking Signal From VAF Meter Locate VAF meter measuring vane and remove connector. Connect SIGRTN, VREF and VPWR to VAF using jumper wire. Leave VAF circuit open. Turn ignition on. Measure voltage between VAF terminal and SIGRTN terminal. Voltage should be as listed in VAF METER VOLTAGE VALUES . If voltage is not as specified, go to step 4. If voltage is correct, repair VAF circuit between ECA and VAF meter.

4) Checking VREF At VAF Meter Turn ignition off. Remove VAF meter connector. Turn ignition on. Measure voltage between VAF wire and SIGRTN wire. If voltage is 4.5-5.5 volts replace VAF meter. If voltage is not 4.5-5.5 volts, go to CIRCUIT TEST A7.

5) VAF Signal Without VREF Locate VAF meter air door. Turn ignition off. Remove meter connector. Using jumper wire, attach SIGRTN and VREF connector terminals to VAF meter. Leave VAF circuit open. Turn ignition on. Measure voltage between VAF terminal and SIGRTN terminal on VAF meter. As flap is moved, voltage should be as listed in VAF METER VOLTAGE VALUES . If voltage is correct, repair VAF circuit between ECA and VAF meter. If voltage is not correct, go to step 6.

6) Remove VAF meter connector. Turn on ignition. Measure voltage between VPWR wire at VAF meter and ground. If voltage is greater than 10 volts, repair SIGRTN wire to ECA. If voltage is 10 volts or less, go to PINPOINT TEST VPWR.