A couple week ago I filled my tank and the fuel gauge went to full, after 100 miles, still pinned at full. On the next start it fell below empty. Occasionally (twice in the last month) it goes back to full, only to fall to empty shortly after.

I had the codes read here's what I got:
P0643 (High voltage output from the sending unit)
P1233 (Fuel Pump Driver Module Offline)
B1201 Fuel gauge system not working

I had the fuel pump/sending unit replaced (as per the tsb). didnt fix the problem.

Next I removed the FPDM, it was slightly corroded but not horrible, and plugged it into one of the trucks at my work. The gauge on the other truck worked fine.

So as far as I can tell it is not the sending unit or the FPDM.

Does anyone have any ideas?

 

you replaced the fuel pump/sending unit before or after the issue started?

Maybe you got a bad part?

Thats all I can think of...

 

i have this prob to but i just never put gas in my truck. lol.


sorry i couldnt help you i hope you get this fixed.

 

I put $100 in my tank last week Got in my truck and it said I had a 1/4 tank. I pulled up to the next pump, as the nozzle didnt click my card shut it off at 100. I was ready to go strangle someone and I could only fit 8 dollars more. Drove it around and the gauge went up to full slowly and has been working right since.

Let us know if you find out anything.