Volume Airflow Meter

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

Fig 1: Identifying VAF Meter Circuits (VAF)

VAF CIRCUIT PIN IDENTIFICATION

Circuit	PCM Pin	BOB Pin	Wire Color
SIGRTN	2C	46	BLU/YEL
VAF	2E	43	LT GRN/BLK
VMREF	2B	18	LT GRN/RED
VPWR	3I	37	YEL/GRN

1) Turn ignition off. Install BOB. Turn ignition on. Measure voltage between VAF and SIGRTN pins while moving vane in VAF meter. Voltage should be as specified in VAF METER VOLTAGE table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 3).

2) Measure voltage between VMREF and SIGRTN test pins. If voltage is 7-9 volts, circuit is okay. Return to QUICK TESTS if sent here from there. If not sent here from QUICK TESTS, temporarily substitute known good PCM. If voltage is not as specified, repair VMREF wire to VAF.

3) Unplug connector from VAF meter. Using jumper wires, connect VPWR, VMREF, and SIGRTN terminals on VAF connector to corresponding terminals on VAF meter. Leave VAF wire disconnected. Measure voltage between VAF and SIGRTN pins on harness connector while moving vane in VAF meter. Voltage should be as specified in VAF METER VOLTAGE table. If voltage is as specified, go to next step. If voltage is as specified, repair VAF wire to PCM.

VAF METER VOLTAGE

Door Position	Volts
1/8 Open	3.24
1/4 Open	5.60
3/8 Open	5.62
1/2 Open	5.83
5/8 Open	6.02
3/4 Open	6.57
7/8 Open	7.46
Full Open	7.87

4) Unplug connector from VAF. Using jumper wires, connect VPWR and SIGRTN terminals on VAF connector to corresponding terminals on VAF meter. Leave VAF and VMREF wires disconnected. Measure voltage between VAF terminal at VAF meter, and SIGRTN pin at harness connector while moving vane in VAF meter. Voltage should be as specified in VAF METER VOLTAGE table. If voltage is not as specified, go to next step. If voltage is as specified, repair VMREF wire to PCM.

5) Unplug connector from VAF meter. Turn ignition on. Measure voltage between SIGRTN and VPWR wires. If voltage is more than 10 volts, replace VAF meter. If voltage is not more than 10 volts, go to next step.

6) Unplug VAF meter connector. Turn ignition on. Measure voltage between VAF meter VPWR wire and ground. If voltage is more than 10 volts, repair VAF wire to PCM. If voltage is not more than 10 volts, go to PINPOINT TEST VPWR.