Quote:
Originally Posted by aa040371
Posting in 4th Gen forum as my car is a 2007 Limited V6 (with about 130K miles), but I imagine some of the discussion will be relevant to other generations.
Also, I've read through some of the other posts here on fuel gauge issues and sending unit replacement and watched several videos, e.g. Tim the Toolman...I have a few specific questions, though, and wasn't sure if I should kick up any more dust on the other long threads. So starting this one.
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A week or so ago I filled my gas tank. The next day (or two?) when I went to start my car in the a.m. I noticed that the fuel gauge needle on instrument panel remained pegged at empty with the amber "low fuel" warning light on. I knew it wasn't a low gas situation, although I went to nearest gas station to top off anyway just to be sure (tank was still almost full). Also, the "range" (aka miles-to-go) digital read-out still indicated I had ~375 miles to go before empty.
I drove around the rest of the day and needle remained set on "empty". But next day when I started car, fuel gauge was reading full and has been working normally/as expected since (e.g. it now reads 2/5 full).
So, some questions:
1) Given the "one-time-only" occurrence, how concerned should I be right now? Do I wait until it is permanently mis-reports fuel level or address it now?
2) How can the needle be reading empty but the "range" readout not be affected (as in still be accurate)? I would have assumed both had to tie back into what the system thought fuel level was?
3) I understand that for my car I can access a fuel tank hatch under back seats although for some dumb reason I can't replace anything from this access hatch...is it worth pulling the seats to inspect and or clean off something and/or test something. Or, again, should I wait until issue is permanent or at least actually occurring in real time.
4) A general automotive expert I know suggested that if the low fuel warning light is on but needle is stuck on empty, that the fact that the light is on may indicate source of issue is likely the instrument cluster. Does this make sense?
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My best guess is that the fuel level sensor in the tank is OK and sending the proper signal, which goes to the instrument cluster and I would also think the signal is also send separately to the ECU responsible for the mileage calculations, I'm not 100% sure that's how it works but I do know that each of the gauges is the instrument cluster has a "stepper motor" to make each gauge work, so I think what is happening is the fuel gauge stepper motor is going bad, but the ECU is still getting the signal to the center info readout for mileage calculations.
These stepper motors can be replaced without replacing the entire instrument cluster, but it involves de-soldering the old/defective one and then soldering in the new stepper motor.
But wait for other replies, hopefully someone may know more on this....maybe
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BlackWorksInc
will stop by and comment, he's a Toyota Tech and could possibly give a more precise answer.
That all being said I myself would wait until it becomes a permanent issue before fixing it, it may never happen again and you can always stop and get gas if you're worried about getting too low if it does happen again, but in the meantime I would do exactly what you're doing now and getting as much info that could be causing the issue and sourcing parts for the future if needed.