[nightrider7731]

Time to join the 05-06 Rubi ranks with O2 errors. My son inherited my wife's 05 LJ Rubi (auto), lives about 1.5 hrs away, and had several inspection issues. I lent him my 04 TJ Rubi back in Dec while I had an extended vacation. The LJ always had one O2 that would throw an error unless we got gas at this one station. We would go there prior to every emissions test. After getting him new tires, replacing brakes at all corners (and filling divots from the pad ears), a water pump that blew suddenly with no weeping, oil leaks, and a few other issues, the LJ suddenly had shifting issues (hard shifting, not shifting till 3000RPM+). I checked the codes (expecting just the one), and had P0031, P0037, P0051, P0057, P0700, and P0562. The alternator tested clean (14.3v DC, diodes good, 0.03 AC), but battery was a hair low and failed the shop test, so I swapped it out. When the P0700 became a permanent MIL, the gears started slipping. Reset codes and tranny went back to hard shifting. I'm hoping the P0700 is a side affect of the power issue. Replaced all O2 sensors (w/o any expectations) and no change. Checked wiring from PCM plug to each O2 plug. Check PCM plug out to PCM plug in. Checked grounds. Checked all non-grounded circuits for shorts to ground. All good.

I sent the PCM to G7 and they said they found no hardware errors, but saw software errors and re-flashed it. I'm a little skeptical about this answer. Plugged it back in and the errors returned. O2 errors where immediately permanent MILs with corresponding pending errors.

I saw a trick online where you cut the connector off an old O2 sensors, plug it into the harness, and connected the heater leads to a head light. When I started the jeep, the expectation was that the heater circuit would turn on the head light. However, it did not. By mistake, I turned the key on, but not to start, and noticed the head light powered on for a brief period. I heard a click from the PDC and tracked it down to the ASD relay. After some research, I found out that the power systems cycles 'on' with the key, but shuts down after around 1.8 second if not started as a safety feature (fuel pump shuts down as well as other items). I was getting 5.2v across the head light pins. So now I know the PCM is able to send power to the O2 heaters when 'on', but not when the jeep is running. I rigged a test where I ran 12v through the PCM plug to the heater circuits, and check the volts on the signal side at the PCM plug. Within a few seconds of power, the O2 signal circuit started registering a voltage. Long story short, all four O2's heated enough (proving the heater worked) to start receiving O2 signals through the other circuits.

I plan to reach out to G7 tomorrow. Since I can't find any PCM schematics, my thought is the P0562 might have something to do with voltage being sent to heater. It can send enough juice when it's not running, but can't when it is. I'd hate to have to replace the PCM after all the horror stories with the TCM, SKIM, etc. We'll have to see where this goes.