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Discussion Starter #1
PCM codes after new one installed P0031 P0037 P0051 P0057
Installed a second remanifactured PCM from Chrysler and still get all 4 of those codes. Origional PCM gave me u0101 and P1603, limp mode every time I pulled and hooked up battery. Had it at dealership and swapped second PCM in this morning. It's the latest flash, didn't have O2 sensor issues before. Transmission shifts fine now.
Time for a LS?
 

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It is always time for a LS. This is on your TJ right? I ask because this is a common problem with JK's. The TJ's pcm sends power out to all of the O2's individually but they all share a ground. G105. So check all the grounds. I find it unlikely as that this ground is for a lot of things. Usually heater power is a switched feed from the asd. If the vehicle runs then pcm power is okay it is just the output for the heaters. In the shop you can cycle the heater circuits with a scanner and check the power/ground at the O2's. The JK's would burn up the control inside the pcm, is this a remanufactured PCM?
 

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Discussion Starter #3
It is always time for a LS. This is on your TJ right? I ask because this is a common problem with JK's. The TJ's pcm sends power out to all of the O2's individually but they all share a ground. G105. So check all the grounds. I find it unlikely as that this ground is for a lot of things. Usually heater power is a switched feed from the asd. If the vehicle runs then pcm power is okay it is just the output for the heaters. In the shop you can cycle the heater circuits with a scanner and check the power/ground at the O2's. The JK's would burn up the control inside the pcm, is this a remanufactured PCM?
Yes this is on my 2005 LJ Rubicon. The JK is fine with 160,000km. This is with the second remanifactured PCM from Chrysler at $1300. My Chrysler mechanic buddy had the star scan here yesterday after we installed the second one at the dealership. You can unplug all O2 sensors and when one is plugged back in all 4 codes come up. We're thinking something is wrong with their latest flash as both the new PCMs do this. When I put the Origional back in I get the P1603 and u0101 again. No O2 codes.
 

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After turning ignition key to the ON position without cranking the engine, the Malfunction
Indicator Lamp (MIL) should remain illuminated solid. If the MIL flashes for 10 seconds
approximately 15 seconds after turning the key to the ON position (without cranking the
engine) and then returns to solid illumination, the vehicle is not ready for I/M testing.
Perform the Repair Procedure.
Does this happen?
 

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Discussion Starter #5
After turning ignition key to the ON position without cranking the engine, the Malfunction
Indicator Lamp (MIL) should remain illuminated solid. If the MIL flashes for 10 seconds
approximately 15 seconds after turning the key to the ON position (without cranking the
engine) and then returns to solid illumination, the vehicle is not ready for I/M testing.
Perform the Repair Procedure.
Does this happen?
I remember reading this but havnt got to that repair as it was the transmission not the O2 codes initially.
Thanks
 

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Discussion Starter #7
I have a thread on ROF about replacing the PSM in my 2005 Rubicon awhile back.

After the dealer installed the replacement from the Chrysler parts house I had codes indicating a problem with the O2 sensors. Had to replace all 4 O2's, and that worked.

http://www.rubiconownersforum.com/forums/22-tj-communications-electronics/91473-codes-all-o2-sensors-bad-pcm-bad.html
I had a P0161 and changed that sensor but it was a chaffed wire so fixed it and put old one back in a couple of summers ago. 4 sensors don't fail at once. We have the star scan in the garage at home and you can see the resistance change on all 4 when you start it cold and it warms up. The CEL comes on as soon as its started though. I think we'll try the wiring mod next as it does have the flashing CEL when put in run position.
Changing oil and rotating 37's on JK right now. LJ won't get insured till April. Hopefully figured out by then.
 

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Discussion Starter #9
PHP:
The idea of changing all 4 O2's was to eliminate at least one potential problem. Considering that O2's are relatively cheap compared to dealer shop time it was cost effective. And in my case, it worked.
I consider myself fortunate to have a jeep buddy who's also a Chrysler mechanic so the wrenching is done in my garage and specialty tools can be brought home.
image.jpg
 

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I don't understand, why is your LJ so low? lol.
Nice garage. I had to get a job where there is a shop. It works out great but no beer allowed.
 

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Discussion Starter #11
I don't understand, why is your LJ so low? lol.
Nice garage. I had to get a job where there is a shop. It works out great but no beer allowed.
Ya, the last gas plant I worked at had a huge shop. We fixed all our toys on nightshift and weekends.
We just fired up a new 400 mmscfd plant so I have to keep an eye on things a bit more till it lines out. No personal jobs for a bit.
The LJ will be lifted when it decides to be reliable. Took me 3 years to find one I wanted. (Even the color)
 

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Alaska-HWY how was your issue finally resolved? I am trying to work through having these four codes with an additional P2098. The two downstream sensors have been replaced and I have the upstreams on order, but it seems something common to all four must be in play. Jeep runs fine.
 

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My 05 Rubicon ran fine too but had codes and the PCM checked bad. I would have kept driving it that way but it wouldn't pass the required smog check for registration. Eventually replace PCM, all 4 O2 sensors, and OPDA .
 

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Thanks for the responses. I received the upstream sensors today, so those will go in. I will start researching PCM starting with Norm’s link.
 
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