Bonez

As some know I just took a 700+ mile round trip. Drove down in the pouring rain, then rain and sunny days on and off all week. On the way home, approximately 100 miles out all the sudden the fuel gage just bottomed out and the dash said low fuel. Now I know I had enough to get home as it only took 3/4 tank to get there and the whole time back it was showing full until this happened. I stopped at a station to get sodas but left the car running with ac for the family. Once home I shut it off and back on, shows 1/4 tank and gage working??? what caused it to just show empty suddenly and stay on empty until cycled again?

Car ran awesome and was showing an average of 36mpg going but coming home was mostly uphill through the mountains and averaged 24mpg I was also hauling a 200 pound scooter and all the stuff we won or bought... the HHR was packed coming home.. I did the math and the dash was spot on.

Oldblue

Check the fuel pump connector up under the car on the passenger side, any loose wires, check the fuses in both fuse panels, any loose?

donbrew

CEL? Should have been if there is anything wrong with the sensor; P0461-P0464. A CEL should set if the fuel level does not change by 1.6 % over a distance of 120 miles. Maybe you didn't drive far enough for it to set. However, you describe the exact behavior that a code would trigger.
The BCM uses the level indicator for calculating fuel economy. So, the BCM was getting data.
It is a digital connection between the BCM and the IPC, so all the gauges would be reading bad if it was a connection to the IPC.

I guess that leaves a broken gauge or broken trace on the IPC pcb.

Bonez

Ill have to check connections and all once the rain stops and ground dries up.

greg8453

It's possible the sender has a bad spot on the resistive material and the computer didn't like it and it reset when you restarted the car.

Oldblue

Yes, a very plausible situation

greg8453

If it is the sender I would expect it to do it again. Modules don't like any signal out of range. A trucker driving by and keys his CB can light up the dash on your car. Restart and normal resumes. Try finding that problem. Yikes.

donbrew

All of the fuel data is in digital format from the tank to the BCM; BCM to IPC. It is all carried on the serial data bus.

Oldblue

Greg, what’s the yikes for? Bonez wil try finding the problem when the rain clears , give him a chance.
We are giving possibilities of the problem.

Bonez

I will run the code reader in a bit here and see if anything pops up on it.