Novak Conversions Jeep Wrangler TJ engine mounts

O2 sensor heater circuits low on all four

obsessedmechanic

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A little backstory this is actually not my Jeep but a very close friends. I am a seasoned mechanic with 13 years of experience. He brought me the vehicle after replacing all four O2 sensors. Replacing the PCM with a Wranglerfix PCM and getting to his own wit's end with it. I started by pinning out and checking resistance and continuity on the O2 wires and not just the heater circuit. Everything was checking out but I still went ahead and replaced the g104 ground. I then turned to the O2 sensors and replaced all four of them myself with ntk sensors. When that didn't work I decided to load test every wire in the O2 system and everything still checked out. What I am seeing is a maximum voltage of 4 volts being supplied from the PCM to the O2 heater circuits. I called Wrangler fix and spoke with Jay and he was very insistent that it was some sort of wiring issue. Me at this point throwing parts at it decided to try a Tipm as I know there the center of all power distribution on these vehicles. Still nothing. I am at a loss and I no longer know what to do. I've tried everything from overlays to load testing and it just really seems like a PCM issue to me. Has anyone else ran into this?
 
Have you tried disconnecting the other sensors that share that vref circuit in case one of them is shorted to ground and pulling the vref down? I don't even know if there are any other sensors on that vref circuit on a 2009, (I don't have access to 2009 manuals since this is a TJ forum and TJs were only made from 1997-2006, what you have is a JK).
 
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I looked at a schematic and it looks like both the heater voltage and the signal voltage originate at the ECM and I don't see anything else on the circuit. Sorry I'm no help.
 
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Just a FYI this is a TJ forum for 1997-2006 Jeep Wranglers.

You might want to post on the sister wranglerjkforum.net.

Meanwhile let's add @Wranglerfix into the conversation.

-Mac

That is my bad I apologize. I was thinking the was until 2010 but I'm not a jeep guy myself lol. That would be my bad completely. I'd love to get on contact with someone at Wranglerfix who seems to care though. Jay was professional but he wasn't willing to really listen to what I had done and tried.
 
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Have you tried disconnecting the other sensors that share that vref circuit in case one of them is shorted to ground and pulling the vref down? I don't even know if there are any other sensors on that vref circuit on a 2009, (I don't have access to 2009 manuals since this is a TJ forum and TJs were only made from 1997-2006, what you have is a JK).

Oh yes, disconnected all but one at a a time when I did the 02 heater test via my snapon scanner and still nothing. Even checked the b/u light circuit and the EGR valve circuit as they also ground at the g104 and I wanted to make sure they weren't pulling or back feeding.
 
Wife's got a 13 JK...we had a 12 until she totalled it into my TJ (long short story).

Seems like every other or all electrical problems with JKs are the TIPM.

-Mac
 
Wife's got a 13 JK...we had a 12 until she totalled it into my TJ (long short story).

Seems like every other or all electrical problems with JKs are the TIPM.

-Mac

Definitely! Most Chrysler vehicles though. I work on the ram trucks daily. I have a fleet of 35. That's why I went through with putting one in it. I thought for sure it would be the tipm after everything else
 
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Novak Conversions Jeep Wrangler TJ engine mounts