heated o2 sensor circuit problem
Thread Starter
TECH Regular
Joined: Jan 2007
Posts: 403
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heated o2 sensor circuit problem Hi everyone, I have a problem with the o2 sensor heater circuit in my ls swap harness. Im pretty sure i found my problem, but i want to make sure i understand how the circuit works. My question is, does my pcm control the o2 sensor heater by switching a ground on and off?
my harness is for a 03 lq4, blue/ green harness.....
I could tell that one of my oxygen sensor heaters wasn't working because of very slow switching in my o2 sensors..
The heater has power to it, and if you manually ground the other side of the circuit, the heater will start working.
So I traced the heater groundwire back to the pcm. And found that the groundwire was wired to the wrong pcm pin.
my harness is for a 03 lq4, blue/ green harness.....
I could tell that one of my oxygen sensor heaters wasn't working because of very slow switching in my o2 sensors..
The heater has power to it, and if you manually ground the other side of the circuit, the heater will start working.
So I traced the heater groundwire back to the pcm. And found that the groundwire was wired to the wrong pcm pin.
On The Tree
Joined: May 2014
Posts: 109
Likes: 1
The PCM does not switch the ground on/off (sinking), PCM uses the + (Purple wire usually). Did it throw any codes with this issue? You might just have to connect your tan (heater -) to a ground or to the case of the O2.
Make sure you aren't trying to use a case ground >2002 pcm with isolated ground O2 sensors and vice versa.
http://www.lt1swap.com/vortec_o2_sensors.htm
The tan on isolated ground O2 sensors will run to a bundle of grounds inside the harness...I undid mine since they are prone to corrosion in my particular application and ran them to a copper buss bar instead.
Make sure you aren't trying to use a case ground >2002 pcm with isolated ground O2 sensors and vice versa.
http://www.lt1swap.com/vortec_o2_sensors.htm
The tan on isolated ground O2 sensors will run to a bundle of grounds inside the harness...I undid mine since they are prone to corrosion in my particular application and ran them to a copper buss bar instead.
The PCM does not switch the ground on/off (sinking), PCM uses the + (Purple wire usually). Did it throw any codes with this issue? You might just have to connect your tan (heater -) to a ground or to the case of the O2.
Make sure you aren't trying to use a case ground >2002 pcm with isolated ground O2 sensors and vice versa.
http://www.lt1swap.com/vortec_o2_sensors.htm
The tan on isolated ground O2 sensors will run to a bundle of grounds inside the harness...I undid mine since they are prone to corrosion in my particular application and ran them to a copper buss bar instead.
Make sure you aren't trying to use a case ground >2002 pcm with isolated ground O2 sensors and vice versa.
http://www.lt1swap.com/vortec_o2_sensors.htm
The tan on isolated ground O2 sensors will run to a bundle of grounds inside the harness...I undid mine since they are prone to corrosion in my particular application and ran them to a copper buss bar instead.