jhogan2424

I just bought an Autometer air/fuel ratio guage for my 93LX 5.0 and I am having trouble trying to wire it in. It only has three wires.... red, black, and purple. The red and black are easy. But the purple.... I know it is wired to the oxygen sensor and I know where the sensor is. BUT, I don't know which of the wires to run it to. And, where does to 02 sensor wire go in the engine compartment? If I knew where it is under the hood I wouldn't have to run a wire all the way to the 02 sensor on my headers. Anybody got a clue to which sensor wire I should run the guage to?

luckythirteen13

there should be 2 white wires and a black one coming from the o2's. i believe the black wire is the sending wire and the 2 white ones are for the o2's "heater". i would run the wire from the gauge to the o2 wire just after the wire connection. that way if you replace the o2's you wont have to disconnect the air/fuel ratio gauge.

jhogan2424

That's a good point about the connection.... I have to be absolutely sure that the black wire is the sending wire because the instructions that came with the guage say if you hook up the a positively charged wire to the sending wire (on the guage) the guage WILL be damaged. Exactly how sure are you? And thanks for your help!!

luckythirteen13

well if your realy worried that the gauge will be ruined, get a voltmeter if you dont already have one. stick the possitive wire into the black wire and the negative to a ground. one of the white will read 12v...thats not it. the other i think will read the same just negative 12 cause the current is going the opposite direction. check the volt meter on the black wire....i believe it will read a low number. the car will need to be on when you test the black wire...assuming its the sending wire.....which im sure it is.

roundman

whoa there guys, DC current only flows in one direction.
according to my EEC IV manual, the HEGO (heated exhaust gas oxygen) sensor has three or sometimes 4 wires coming to/from it. one is key power, 10.5 volts or less, when key is on, two are grounds and one is the HEGO signal you want to go to the meter. with the voltmeter negative probe connected to a good ground, look for the signal that is less than .5 volts, the lowest voltage measured is the signal out wire that you want to splice into.

luckythirteen13

i know some cars have 4 wires but arent the mustangs 3?

roundman

not real sure, never really looked that close at mine