4-wire O2 sensor - how to take a reading??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by mike reeh, Aug 4, 2003.

  1. mike reeh

    mike reeh 1/2 ton status

    Jul 23, 2001
    Likes Received:
    San Diego, CA
    Ive had the autometer air:fuel meter for a while.. Before I tore my truck down I had it working with a 1-wire sensor, worked great.. I have since rebuilt the entire truck including exhaust and I welded O2 sensor bungs into my thorley headers... I installed new bosch (ford) 4-wire sensors, one in each header collector. I got these sensors brand new from andy quaas (realsquash) a couple years ago and finally have gotten around to installing them. I was pretty sure I didnt need the heater wire hooked up but I cannot get any sort of reading on my guage or with a voltmeter from either sensor and yes they are very hot when Im trying.. Is there something Im missing? Im wondering if some of the wires need to be connected in a certain way (to ground or +12v or otherwise)... Its really frustrating me.. I can post a pic of the sensor if needed...

    there are 2 white wires, a grey, and a black



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