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Auto Go, ASE Certified Technician
Category: Car
Satisfied Customers: 849
Experience:  ASE Master Certified, ASE Certified Undercar Specialist, ASE Advanced Engine Performance Certified.
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99 legacy: fuel gauge isnt working, also hard to day

Customer Question

code po463 on a 99 legacy and the fuel gauge isnt working, also hard to fill if it is a hot day
Submitted: 5 years ago.
Category: Car
Expert:  Auto Go replied 5 years ago.
Hello and welcome to Just Answer!

Sending unit specification is, on the main sensor full 0.5 to 2.5 ohms, and empty is 50 to 52 ohms of resistance. Specification on the sub-sending unit is 0.5 to 2.5 ohms of resistance full and 42 to 44 ohms of resistance empty.

If you are getting 50 ohms on the sub sending unit, then you have a faulty sensor. If you are going to replace one sensor, I recommend on this application to replace both. Also be sure to double check all the wiring that you can see. It's not uncommon for rodents to get in there and chew on the wiring. I've seen this many times.

Thanks and let me know if you need any more help.
Customer: replied 5 years ago.

I think you are misinterpreting what I am saying. I had both senders out and hooked up a multimeter to them to measure resistance. As I moved the float arm thru its range the resistance varied from 1 to 50 ohms. It didnt just stay at 50 ohms throughout. Like I said I measured the resistance at the contacts on top of the sender units with them removed from the tank.


Where would be the next point I could go in the car to check the wiring and what readings should I be looking for?

Expert:  Auto Go replied 5 years ago.
I did understand you. If you will notice in my first post, I said that the range spec for the sub sensor is .5 to 44 ohms. If you are reading 50 ohms at full empty position on the sub sensor, then according to spec, this is no good.

The definition of the the code P0463 is fuel level sensor circuit high voltage.

The instrument cluster sends a reference voltage to the sensor and a ground. The sensor varies the resistance of the reference voltage to ground. The cluster monitors the voltage on the supply wire. As the resistance decreases, the reference voltage is pulled down. The cluster monitors this voltage to determine fuel level. If the module sees abnormally high voltage, this is because the voltage isn't being pulled to ground. This is usually due to a faulty sender, or an open circuit such as a cut wire.

The fuel level circuit is fairly simple in the fact that all that is involved is the instrument cluster, the 2 fuel gages and the wiring between.

You could remove the instrument cluster and disconnect connector A. Now measure the resistance between pin 3 (brown/black wire) to ground. It should not be open circuit. It should also not be over roughly 100 ohms (combined resistance of both sensors as they are wired in series). If it's open circuit, then measure the resistance between pin 3 and the brown/black wire at the fuel tank. This should read nearly 0 ohms. If not, then you have a bad wire between the cluster and the tank.

check that wiring out and let me know. Thanks
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Customer: replied 5 years ago.
By the way which connector is the A connector? THere are 3 big ones and one small one.
Expert:  Auto Go replied 5 years ago.
Here is a wiring diagram of the instrument cluster connectors. Notice the letters before the pin numbers on the 3 large instrument cluster connectors. The letter corresponds to the connector letter.

compare the wiring colors in the diagram to the ones on the car to determine which connector is which.