I've got a crazy situation going on with the GXP. Yesterday I drove from Dallas to Baton Rouge. Stopped 1/2 way for gas. I noticed that the gas gauge had been stuck at 1/3 even though it took 16 gallons of fuel. After I gassed it up, the gauge still reads 1/3 tank AND the trans started shifting very hard. I drove it the rest of the way with the trans shifting hard.

This morning the car won't start it will just sputter a bit. Then I looked at the gauges and the temp says 200 degrees??! Car is dead cold. So I scanned the PCM, and PCM says coolant temp is 212 and outside air is 102 (its about 75 degrees outside). I checked all the obvious stuff, looked for loose wiring, checked the pcm connection etc, but I can't find anything amiss.

If anyone has seen this or has ideas, please let me know. I'm supposted to be at work in Dallas tomorrow, so this is going to be a huge pain if I can't get the car started.

I checked trouble codes, and there were no stored trouble codes, but the following pended codes were listed:

P0412 P0418 P0443 P0449

Thanks in advance for any help!

412 Secondary Air Injection solenoid circuit
418 Secondary Air Injection pump relay circuit
443 EVAP purge solenoid control fault
449 EVAP VENT solenoid control circuit

Check fuses for these items. Otherwise it'* a short somewhere(not likely considering age, but..... Hope the PCM doesnt have partial dementia. Probably not under warranty anymore, is it? The tranny shifting hard could have been engine influence. Torque Management can do weird thing where a failing part wouldnt seem connected to another acting quirky.

Thanks Venom, no warrantee. But I have some good news. I disconnected the battery for about 5 minutes. Reconnected and both the gas gauge and coolant gauges were reading correctly! Then she started right up! And the trans is shifting fine!

However... it was running on a high idle and the ac would not come on (just blowing hot air). So I shut it off and restarted. Idle was normal but no a/c. So maybe there is still some issue, but its running and driving so I will try driving some more to see if its ok.

Also, I checked and there are not any codes now. Still a pretty weird situation.

Thanks!

Lets keep our fingers crossed. Good move on disconnecting the battery. It slipped my mind. Probably a first thing to do when **** gets that weird. These days I think they have given the PCM way to much control. It makes everything so smooth and nice, until often simple things butt head for who knows why.

Check out the vacuum lines for leaks. Lots of codes makes me think vacuum leak. Not sure where the MAP is on a GXP but if that line goes the PCM wont know the air pressure and shifting, idle, etc will all be off.

I made it home without incident yesterday. Car drove perfectly except for the lack of A/C. That is really a trip that the PCM thought a dead cold engine had high coolant temp. Almost like it needed a reboot to wake up. Seems like the sensor readings froze to a value and did not change, and that started all the problems. And yet I never got a check engine light, and the engine ran fine until I tried to start it the next morning. In my original email, I didn't even mention the fact that when I was coming into Baton Rouge during rush hour, I got stuck in a traffic jam, and a little bit of steam was coming from under the hood. At that time, I figured the trans was dying. I heard a few hising sounds, then I saw a poof of steam or something come out of the a/c vents, so I turned off the ac. Then a few minutes later when I tried turning it back on, it did not cool, so I left it off.

Regarding the a/c, I checked last night and the compressor is running, the low side is at 27 lbs when loaded, and one of the lines is extremely cold as I would expect with a healthy a/c. But it won't cool off in the car. The air is just slightly less than ambient. Seems like it must be something in the temp control unit or whatever regulates the temp. During the drive, I tried every variation of climate control settings to wake up the a/c, but to no avail.

Weird stuff for sure, but it got me back home, so that is a big relief.

After doing some research, I found that the low-pressure side should be around 40 with the compressor running. I added some R134, low side pressure is 38 and she'* blowing cold. Again, this is all pretty crazy and I really don't understand what happened. Somehow the ac system released freon very quickly, and yet its holding fine now.