SC430 was garaged for six years, and occasionally I jump-started and drove it to check it still runs. Yesterday I filled it up, and the fuel gauge needle didn’t go up. It kept showing near empty. I went to another gas station, and no more fuel could be added, so the tank is full. As I drove the car, the gauge reading kept decreasing past the empty line and to the E letter, and the center console remaining mileage number gradually decreased toward zero and now shows low. The car keeps driving while the gauge and console both show low (80 miles so far, so it’s well past the 35 miles range typically remaining past the Low reading. I’m using the trip odometer for now to keep track of the fuel (premium).

Question: what is the magic reset sequence for the gauge to work again? Some videos show ECU fuse reset for a Camry with the same issue, but here I couldn’t find a fuse for the ECU. Or is there a cable to be disconnected and reattached? Or a float lever to push on (how)?

 

Easiest thing to do is disconnecting the battery. You will loose the seat memory and radio stations but that’s easily restored.

 

Thank you. Just tried this: took off the negative battery cable for 10 seconds (enough?), reconnected. No change, the needle is still pointing at E.
While parked, the battery went flat multiple times, so presumably the ECU got reset multiple times as seats and radio lost their settings. I wonder if that might have retrained or lost the ECU limits for the fuel gauge, as the fuel was low, similar to the seat limits. Other things I’ll consider eventually are taking off the rear seat cushion to peek at the fuel pump assembly, and re-learning the ECU (a 30-minute method).

 

If you can start the car, it’s not your fuel pump. Most likely it’s your sending unit. Unfortunately, it’s inside your tank. It won’t be the fuse cuz other things in your cluster are OK. Other thing you can check is the wiring, especial grounding. Poor grounding could cause the problem. Do you have TechStream? It may show ETC that could narrow the trouble.

 

Yes, I did get Techstream and the software for it a while ago just in case, but haven’t had a chance to use it yet. This gets added to the to-try list. Thank you.

 

There is likely an open circuit in one of the fuel level sending units due to corrosion from the old fuel. There are two level units: one on each side of the tank. You can access them via the service panels under the rear seat cushion and measure the resistance with an ohm meter.

 

Thank you. I’ll look under the seat hopefully this coming weekend. If anyone knows of relevant videos or schematics specific to the fuel level units, would be appreciated.

Not to start a new thread, but another electrical issue popped up: one brake light bulb went out. For a car just 19.8 years old, unthinkable! The dashboard worked as designed, and the “brake light out” picture is now lit orange. Hopefully, a quick fix (never done it on this car). Could this be somehow related? Battery is old but is Lexus and still holds the charge well. Could the voltage regulator be sending more current into the lines because of the battery age? (just guessing; no fuses popped yet)

 

In my 2002 the fuel gauge would show 1/4 when it was empty and wouldn't show full when the tank was full. Replaced both sending units in the gas tank and fixed the problem. P/Ns: 83320-30500 Sending Unit; 83320-80362 Sending Unit.

Everything was accessible under the back seat, easy job took about an hour diy.

 

Thank you. Good to know.

 

Success. With the existing equipment, the gauge now works. Cleaning the contact pads immersed into (oxygenated, 10% alcohol, corrosive) gasoline with a paper towel and a q-tip on both driver and passenger level indicators (a.k.a. send units) did the trick; I didn't need to buy replacements. Indeed, took around an hour and a half.

Nota bene:

The advice which hasn't been shared by previous posters, yet inevitably relevant, is:
I didn't open the fuel tank gas cap first - without that undoing the fuel line spills gasoline onto the tank. After that, this Lexus smells like a British car. It will sit in the garage for a little while to air out, top down.

Additonal observations from me:
1. I used rubber or chemical resistant gloves - there was dirt and gasoline aplenty.
The gas tank top surface is open to underside and has some 20 years of dirt & dust on in. I cleaned it the best I could before undoing any connection screws. I used paper towels and q-tips with 50% water-alcohol solution to get most of the dirt cleaned.

2. I took pictures which way the top white contacts point.

3. I started on the passenger side - it is simpler.

4. The pump unit (driver side) pulls out up and tilting toward the passenger side. The rubber hose underneath stayed attached. The rubber hose (fuel line) on top disconnects by pulling out the yellow clip completely and pulling the fuel line up.

5. The white electric connector on the pump unit has a catch clip; it is pulled from bottom, away from the connector. Pushing on the top side of the latch doesn't do much to undo the clip. I had to work a thin flat screwdriver between the clip and the catch to help undo it.

Just for those curious, this car does have LATCH for child seats or booster seats, middle of the rear cushions.

Note: nothing of the above is an instruction, but just expressing opinion and describing experience. I recommend to service car at authorized dealer, and follow all manufacturers' recommendations.