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!

_________________
2005 GXP Silver, Gutted Airbox, K&N filter, 14.61 @ 94.31 mph.
1987 t-bird 2.3 turbo, stock motor with home-ported head, big turbo, big exhaust, alky injection, a bunch of other little stuff, 13.65 @ 102 on radials.

The only thing I can suggest as an idea is unplug the battery for a few minutes and let the computer clear, then try again. Hopefully a gearhead will chime in with suggestions...

Wow, sometimes try the obvious, thanks chillin. 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.

Thanks!

_________________
2005 GXP Silver, Gutted Airbox, K&N filter, 14.61 @ 94.31 mph.
1987 t-bird 2.3 turbo, stock motor with home-ported head, big turbo, big exhaust, alky injection, a bunch of other little stuff, 13.65 @ 102 on radials.

Yeah I'd be careful, whatever caused the issue is probably still lurking. This might do the trick to get you home. I'd suggest further diagnostics and driving it easily until you figure out the real issue. Repeat step if problem occurs again to get home. Glad I could help.

Check the battery cables and battery grounds. Make sure there is no corrosion, and the connections are good and tight. Consider using some dielectric grease to prevent oxidation. Then check the ground connections for the PCM.

_________________




1998 3.8 Dodge Caravan 214K
2000 3.3 Dodge Caravan 175K
1949 Plymouth Special Deluxe 4-dr sedan 25K (needs some work!)

I was thinking to tell him the same, but what stopped me is that the 00+ has the battery under the back seat IIRC, shouldn't be such a problem being there (of course, still cannot hurt to check)

In fact, if our esteemed members can be believed, there is a problem especially with the body ground for the battery in the newer models with the battery under the rear seat. (I only know this from reading others' posts - have yet to make the leap to 2000+)

_________________




1998 3.8 Dodge Caravan 214K
2000 3.3 Dodge Caravan 175K
1949 Plymouth Special Deluxe 4-dr sedan 25K (needs some work!)

Hopefully not, but it might be a bad PCM. If you can find such a newer car at the wrecker a salvaged PCM is pretty cheap. You could carry it as a spare seeing how you make some long distance trips

_________________
2001 Bonneville SSEi. 1598xx mi.
great car. Wrecked


Burnt Bonny.

Note if you pull the injectors to obserbe fuel delivery...make sure you leave the plugs in and disconnect the ign. Believe me

The bolt for the grounding strap can bet pretty rusty and corroded. It would have been a better design had the threads in the floor pan not gone all the way through to the outside. Sometimes, the vent tubes from the battery may come loose, allowing the battery vapors to get trapped under the seat and start to corrode connects, and the floor pan itself.

A PCM would have to be programmed for your car's VIN and features, as well as the Pass Key system, for it to work.

_________________
*Gone, but not forgotten* - Black 2000 SSEi, HIR Headlights, Angel Eyes fogs, 3rd brake light overlay, hi-flo cat, 180 degree thermostat, HS 1.9 rockers, LSx yellow springs, Intense FWI, PCM, shift kit, push rods, and 3.4 Pulley. ZZP Power Log.

Thanks all. I made it home without incident yesterday. Car drove perfectly except for the lack of A/C. I'll check the grounds when I get a chance, but I think it must be pcm related or ???. 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.

All I got to say is this is some weird sh......stuff.

_________________
2005 GXP Silver, Gutted Airbox, K&N filter, 14.61 @ 94.31 mph.
1987 t-bird 2.3 turbo, stock motor with home-ported head, big turbo, big exhaust, alky injection, a bunch of other little stuff, 13.65 @ 102 on radials.

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's 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.

_________________
2005 GXP Silver, Gutted Airbox, K&N filter, 14.61 @ 94.31 mph.
1987 t-bird 2.3 turbo, stock motor with home-ported head, big turbo, big exhaust, alky injection, a bunch of other little stuff, 13.65 @ 102 on radials.

Low pressure should be around 44psi under load. Go get you another can of R134 and dump it in there. Please keep in mind though; do not let the LP go higher than 44psi. An easy way to ensure this doesn't happen is to buy a can with the gauge on it.

_________________
2012 CTS-V Coupe, 4k miles and counting.



2005 Bonneville GXP, 200k and SOLD!

Thanks DP, I'll do that.

_________________
2005 GXP Silver, Gutted Airbox, K&N filter, 14.61 @ 94.31 mph.
1987 t-bird 2.3 turbo, stock motor with home-ported head, big turbo, big exhaust, alky injection, a bunch of other little stuff, 13.65 @ 102 on radials.

The reason why it was running funny at first was because the process of removing the battery terminals is considered an idle re-learn. Basically it's like re-booting your home PC. It clears the PCM of all the bugs and learned tendencies it's picked up over time and starts at a base, fresh default. There is a complete idle re-learn driving cycle for GM's at www.OBDII.com .

My suspicion though is that if the problem came up once, you haven't fixed the problem, it'll come back again. If so, we can go through the methodology behind the systems driving those codes and steps for troubleshooting those codes above, or whatever DTC's pop up.

_________________


Retired Bonneville Owner and former GM Tech:
2004 Pontiac Bonneville GXP: Black/Ebony *SOLD*

Summer Toys: Combined 827 RWHP / 877lb/ft RWTQ
2004 Pontiac GTO: Impulse Blue Metallic/Black/M6: lots 'o mods, 415 RWHP / 405lb/ft RWTQ!
2006 Cadillac STS-V: Light Platinum Metallic/Light Gray/A6 - Spectre CAI, Magnaflow exhaust, Speed Inc. tune, 412 RWHP / 472lb/ft RWTQ

Daily Drivers:
2019 Chrysler Pacifica Limited: Mommy's new RGC
2015 Chrysler Town & Country Limited Platinum: Kids new RGC
2007 Chrysler Town & Country Limited: Sold to neighbor
2009 Pontiac G8 GT: L76, Sport Red Metallic
2003 Chevrolet Suburban 2500: Doeskin Tan - 8.1L Big Block... new plow truck
1999 Chevrolet Suburban: Sunset Gold Metallic - Daddy's winter beater and plow truck