MAF wires, and what they are, what to test and what you should find:
A: Red wire, VPWR. This wire supplies battery voltage to the MAF. There are two tests to perform. First, check the wire for continuity from the MAF harness connector to the ECM. Second, check for battery voltage between the Red wire and ground, with the harness disconnected from the MAF, and with the Key On and the Engine Off (KOEO).
B: Black wire, PWR GND. This wire is directly connected to the battery ground. There are also two tests here. For both tests, disconnect the harness from the MAF. With the key OFF, check for continuity between the Black wire and the negative battery post. For the second test, check for battery voltage between the Black wire and the positive battery post.
C: Tan wire with a Light Blue tracer, MAF RTN. This wire delivers a signal back to the MAF from the ECM. It is a ground signal, but it is controlled by the ECM. Do not confuse this wire with battery ground, as it will not always be able to complete a circuit with another positive battery source. Test this wire for continuity between the MAF harness connector and the ECM.
D: Dark Blue wire with an Orange tracer, MAF SIG. This is the wire that sends a signal from the MAF to the ECM. There are several tests for this wire. First, check this wire for continuity between the MAF harness conector and the ECM. Second, connect the DMM to this wire and to the Black wire, and check for infinite resistance. Third, connect the DMM to this wire and to the Tan wire with the Light Blue tracer, and check for infinite resistance. Finally, with everything connected and the engine running, use the positive DMM lead to back-probe this wire at the MAF harness connector , and touch the negative DMM lead to the negative battery post, and make sure that the DC voltage is between .2vdc and 1.5vdc.
Take care,
-Chris
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