imp
Explorer Addict
- Joined
- November 12, 2009
- Messages
- 4,789
- Reaction score
- 787
- Year, Model & Trim Level
- 59 Ranchero F250 D'Line
2004 Ex 4.0L, 154K miles.
The heater is contained in the sensor, and is powered directly by 12 volts. That much I can see from the Ford wiring diagrams. The heater is turned on and off by the PCM, which closes and completes the ground circuit to the heater. Power to the heater is supplied by a fuse which is "Hot" in Start and Run. Therefore, the heater can never be powered if the key is OFF.
Does anyone have a "handle" on when and under what conditions, the PCM turns the heater "ON"? I'm guessing, the heater's purpose is to make the sensor "workable" quickly, without waiting for the exhaust heat to bring it up to temperature.
So, my question basically is, when does the PCM turn on the heater, and does it turn it OFF after the sensor gets heated by exhaust gas? Why do I want to know?
Getting a pesky CEL over and over, does not affect any performance (except my own mental condition!), indicating P0054 "HO2S Heater Resistance Bank 1 Position 2". All 4 sensors have been replaced. No cause for this has been found in the heater wiring. PCM has been replaced in the course of ABS work; old PCM threw HO2S code also.
Any ideas? Thanks! imp
The heater is contained in the sensor, and is powered directly by 12 volts. That much I can see from the Ford wiring diagrams. The heater is turned on and off by the PCM, which closes and completes the ground circuit to the heater. Power to the heater is supplied by a fuse which is "Hot" in Start and Run. Therefore, the heater can never be powered if the key is OFF.
Does anyone have a "handle" on when and under what conditions, the PCM turns the heater "ON"? I'm guessing, the heater's purpose is to make the sensor "workable" quickly, without waiting for the exhaust heat to bring it up to temperature.
So, my question basically is, when does the PCM turn on the heater, and does it turn it OFF after the sensor gets heated by exhaust gas? Why do I want to know?
Getting a pesky CEL over and over, does not affect any performance (except my own mental condition!), indicating P0054 "HO2S Heater Resistance Bank 1 Position 2". All 4 sensors have been replaced. No cause for this has been found in the heater wiring. PCM has been replaced in the course of ABS work; old PCM threw HO2S code also.
Any ideas? Thanks! imp
