I got bored the other night and tested my connections under the hood and all was good til I got to the IAT sensor. 12v dc I did red positive to wire and black ground to the battery and got 4.6v. Did the other test where you should be getting somewhere in 4v range it popped up .04 - .06? Turned my ignition over to see if change but no stayed the same and did test with hooked up and got same .04 - .06v. Is this correct or is it messed up? Any tips would be great.
Could it be bad wiring or bad sensor? Let me know thanks(:

 

Intake Air temp(IAT) sensor will test similar to ECT(engine coolant temp) sensor.

Both get 5volts from Computer on one wire then that voltage passes thru the sensor's internal resistor circuit and back to the Computer on the other wire.

The Ground on this type of circuit is at the Computer, which in theory will be the same 0volts as the engine block but it can read slightly different.

The 5volts on the one wire can read 4.5v to 5.0v
The "return" wire volts can read .2v to 3.5v
The lower the "return" volts the warmer the temp

On your '99 the IAT sensor should be part of the MAF sensor(6 wire MAF)

 

No the maf and iat are separate

 

Any more ideas?