How to test a fuel gauge (tank sending unit) P0463 - GM

P0463 Fuel Level Sensor Circuit Signal High/Open trouble code. In this video I will show you how to test a fuel tank sending unit (float). Typically the spring loaded fingers that ride on the resistor in the tank will break off, ruining the sending unit. The only fix is to replace the float as an assembly or try to piece a new resistor assembly into the existing sending unit. The electrical design of the fuel tank sending unit that GM uses is identical in operation and testing as a temperature sensor. The difference is in what changes the resistance of the external resistor. On a temp sensor, it is temperature, on a fuel level sensor, it is the position of the float. For this reason, I have placed this video in my Section 6 "Thermistors" playlist.

Engine Performance Diagnostics chapter 6 pages 10-11

Symptoms
- in-op fuel gauge
- fuel gauge stuck on full or empty
- fuel gauge works some of the time
- trouble code P0463

Fix
- replace fuel tank sending unit

Tests shown
- description and operation of the electrical circuit
- fuel tank level signal and ground wire tests
- how to perform a circuit integrity test

Tools used
- scan tool
- digital multimeter
- back-probing tools

Playlist
- (Chapter 6) Temperature Sensor, Thermistor Circuit Tests

Related videos
- How to test a coolant temperature sensor (ECT sensor test)

On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!

Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.

[williamhinton]

I was a navy instructor and taught reactor operation and instrument control repair and calibration. Your instruction is on a par with naval training for the reactor controls. Kudos my friend. ET1(SS)

[deankay]

As an ACDelco instructor, we were teaching this in 2002 in classrooms. The values have changed from 0-90 ohms, the 0-240 ohms for higher resolution used by OBD-2. This is a common voltage divider circuit and in the computer is a 5volt regulator, not a resistor. Don’t be fooled. If you had a 2003 Tahoe, how many 5 volts sensor circuits could you find? Dozens! TPS, Air temp, Ambient Air, Cab AC Temp in duct, Fuel yes. So an entire bank of 5 volt regulators even use after start-up for voltage drop compliance testing for sensor integrity. For a low fuel sensor, NTC Thermistors are common on imports, motorcycles even riding mowers. Fuel level on a swing arm can be over active on turns w/low fuel, so the PCM updates the fuel gauge every 8-12 seconds as live reading are not needed. So, a gauge on a motorcycle will use a 5 volt regulator, NTC thermistor and current limiting resistors for the LED low fuel lamp. Not 1, 000 ohms as the linear temp curve is not as accurate. And for those who think any heat in the gas tank means an explosion, they are in a can, surrounded by wax paper & SS Wool, lid is soldered on to provide ground. The PCM see’s near zero ohms, it trips a voltage signal to a low fuel lamp so the resistance is split even between gauge and lamp. Low fuel from GM gives you 2.5 gallons. Toyota gives 3 gallons. Motorcycles 0.5 gallons. Or as the 60’s, 70’s, and 80’s used a taller stand pipe on the petcock to run out, switch to reserve and draw fuel from bottom of tank! How hard was that?
DK, ASE Master, 78.

[Username]

I never seen a great comprehensive Auto electronic guru like Mr Paul.His books and related videos are really making you a great auto tech.

[MrMatthew]

I like how you are thorough, and informational. Half of my auto teachers at school give half ass answers and just tell me what to do instead of teaching.

[nickayivor]

What do you call KNOWLEDGEABLE and SUBSTANTIAL the answer is Sir ScannerDanner
Brilliant video From the start to finish loved it. Thank you very much helpful information video. Take care and have a great day Sir ScannerDanner
From Nick Ayivor from London England UK 🇬🇧

[gladsaxisme]

Thanks for this video I have had problems with my fuel gauge on my Integra type R but rather than showing full all the time it tends to go to empty rather quickly so I went on your channel to get the best way to go about it and I can now attack the problem with more confidence Thanks again

[benmixmaster]

I've had a lot of "HIGH END" training materials, and scanner danners training materials are "HIGH END" as well. He definately demonstraited simple fuel guage Diagnostics in this video, using paper clip at tank connector, jumpering 5 volt reference to harness ground and watching scantool voltage to go from 5v to 0 volts when grounded, proving problem to be towards tank sender unit.Glad that Mr. Danner has made this video and his book available to me and any person who may work on my car some day.

[DIYautotech]

I appreciate the electrical diagnosis videos you have. I have been certified in a few different sub categories as a tech, including advanced electrical diagnosis, but none of my professors came anywhere NEAR as close as you have in making sense out of circuits & showing how the powers/ grounds are switched. I will make sure to tell all my followers about you. Keep it up for the sake of all the younger generation guys who are gonna need to tackle todays advanced vehicles.

[صلاحالحراصي-غض]

God has guide me to you.
I can't even speak or write a comment.
You are just amazing and I like your character.
Recently I bought a tester and a multimeter willing to learn so I'm just a beginner 😅

[fivefortyeyei]

Just purchased the book, Really defined, well im in the first section studying stft ltft trims all this critical knowledge for the price is unbelievable!! GET THE BOOK FOLKS !!
You will NOT be disappointed,

[Waynestarr]

Eric The Car Guy sent me here! You are DAMN good! Very impressed.

[ScannerDanner]

@DIYautotech Thank you! I really appreciate the comment and the word of mouth. Have a great day.

[jzz]

Mr. scannerdanner you are absolutely amazing at how you simplify and explain how this things work. I have learned so much from your videos on here & am so thankful for you sharing this with us on here. Thanks again and I hope you are blessed for the work that you do to help people.

[dazeboy]

Thanks again Paul! Great lesson on Thermistors! I get it now!

[jasonparker]

You are a troubleshooting God! This is something that has boggled my mind about CTS/Fuel sending units for a long time. Thank you!

[mymechanicfriend]

Mann... TOP NOTCH ASE A6 Material Here!!! I am definitely a fan!!!

[michaelbailey]

What a perfect video for what I needed. Thank you for breaking this down!

I have a 2016 cadillac ats-v and the gas guage doesn't work. hasn't worked since I've owned the car. I thought a new fuel pump would fix the issue; since I wanted to upgrade the fuel system. However it didn't fix the problem. Because of this video, I know exactly what to look for now. High 5 to you and your team!

[majstorivan]

ScanerDanner majstore pa ti si Bog! To translate it is :ScannerDanner master you are God :) your videos helped me so much in diagnosing bad wires or sensors etc.By the way i am mechanic working on Renault in Serbia for five years now.I've been so frustrated doing ohm testing that was leading nowhere.Than your voltage drop testing was like a light at the end of the tunnel.I actually solved a problem in 5 minutes that was driving my boss nuts for 2 hours.Thank you.Greetings from Serbia!!!

[kinoadams]

you are the best! am from jamaica and i watch most of your videos, if not all, best teacher i learn so much, i have so much confidence in diagnosing my car! and i am giving you credit for crank sensor bypass test, wow amazing! circuit integrity test!

[gilbertjaramillo]

Super video. Now I can attempt to diagnosis my sender on my motorhome that reads empty. Like you said, if I disconnect the wire plug at the sending unit, I should read 5v with my meter to ground. Thank you!