Tbi swap build thread

[rfmaster]

AC-Delco AFS-75 wire - functional chart

BLUE SIGNAL + ( D7 )
WHITE SIGNAL - ( D6 )
BLACK HEATER
BLACK HEATER

O2 heater draws about 3-4 Amps when cold and drops down as O2 reaches 300C operating temperature. I set up a simple relay circuit that energizes heater whenever ignition is ON. FWIW in modern cars PCM monitors current drawn by the heater circuit. Once current reaches a certain lower limit (some) PCM will shut down heater circuit as PCM logic deems O2 is fully functional, only periodically checking to make certain. PCM will also shut it down at WOT. I have seen numerous explanations why it is done, but for the sake of our application keeping heater circuit that is always ON solves cold header problem that otherwise plagues single wire O2s.

//RF