A/C buttons and Fuel Gage

Replace the instrument cluster . GM had stepper motor issues 2003 to 2006 . Pin out won't help you , The info for the instrument cluster gauges come's over class 2 serial data buss (network) from the PCM - engine computer . Do you know what GM class 2 data network is ? All gauge info comes over one wire from the PCM .
How to repair GM Instrument Cluster Speedometer Gauge Stepper
Buick Class 2 Operation Diagnosis 1998

Hooking up a Tech 2 scan tool an checking for code's an data to the instrument cluster would be the correct diagnostic procedure . But you wouldn't know that , not being a Chevy technician . Not having factory service repair info. manual .

Speedometer
The IPC displays the vehicle speed based on the information from the PCM. The PCM calculates the vehicle speed from the vehicle speed sensor (VSS) circuit. The IPC receives a class 2 message from the PCM indicating the vehicle speed. The PCM also calculates the vehicle speed based on the wheel reference vehicle speed class 2 message from the EBCM. The PCM uses the vehicle speed information from the EBCM as a backup. The IPC displays the vehicle speed information from the EBCM when the PCM detects a malfunction in the vehicle speed sensor circuit.
The speedometer defaults to 0 km/h (0 mph) if the IPC detects a loss of class 2 communications with both the PCM and the EBCM.

Engine Coolant Temperature (ECT) Gage
The IPC displays the engine coolant temperature on the analog ECT gage as determined by the PCM. The PCM monitors the signal circuit of the engine coolant temperature sensor. The IPC receives a class 2 message from the PCM indicating the engine coolant temperature. The IPC illuminates the check gages indicator when a high engine coolant temperature condition exists. The engine coolant temperature gage defaults to 75°C (160°F) or below when one of the following conditions occur:
• The PCM detects a malfunction in the engine coolant temperature sensor signal circuit.
• The IPC detects a loss of class 2 communication with the PCM.
For additional informatin on the engine cooling system, refer to Cooling System Description and Operation in Engine Cooling.
Engine Oil Pressure (EOP) Gage
The IPC displays the engine oil pressure on the analog EOP gage as determined by the PCM. The PCM monitors the signal circuit of the engine oil pressure sensor. When the engine oil pressure sensor resistance is high, the engine oil pressure is high. When the engine oil pressure sensor resistance is low, the engine oil pressure is low. The IPC receives a class 2 message from the PCM indicating the engine oil pressure. The IPC illuminates the check gages indicator when a low oil pressure condition exists. The engine oil pressure gage defaults to 0 kPa (0 psi) when the following condition occurs:
• The PCM detects a malfunction in the engine oil pressure sensor signal circuit.
• The IPC detects a loss of class 2 communication with the PCM.
Fuel Gage
The IPC displays the fuel level on the analog fuel gage as determined by the PCM. The PCM monitors the signal circuit of the fuel level sensor. When the fuel level sensor resistance is high, the fuel gage indicates full. When the fuel level sensor resistance is low, the fuel gage indicates empty. The IPC receives a class 2 message from the PCM indicating the filtered fuel level percent. The PCM uses 2 filters for the fuel level percent. The slow filter is used during normal operation. The fast filter is used when the engine is just started or when the vehicle is in Park or Neutral. The fast filter allows the fuel gage to reach the current fuel level quickly. The fuel gage defaults to empty when the following conditions occur:
• The PCM detects a malfunction in the fuel level sensor circuit. Refer to Diagnostic System Check - Instrument Cluster .
• The IPC detects a loss of class 2 communications with the PCM.
Reviewing the fuel system description will further explain how the system functions. Refer to:
• Fuel System Description in Engine Controls - 4.3L
• Fuel System Description in Engine Controls - 4.8L, 5.3L, and 6.0L.

Yes the fuel tank has to come out to change the fuel pump. But are you sure that is the problem ? Your vehicle has a Fuel Pump Flow Control Module (electronic's ) Or is it just your fuel level sensor you want to replace ? And to your question of if the fuel level sensor is bad will the car shut down if the gage says it is emty but it is not? No ,this will not shut down the vehicle. You probably have no idea of the complexity of the electronic's involved an the thing's that can cause the gauge not to work .
Fuel Gage
The instrument panel cluster (IPC) displays the fuel level as determined by the ECM. The IPC receives a serial data message from the ECM indicating the fuel level percent. The fuel gage defaults to empty if:
• The ECM detects a malfunction in the fuel level sensor circuit.
• The IPC detects a loss of serial data communications with the BCM
• The BCM detects a loss of serial data communications with the ECM
When the fuel level is less than a pre-determined value, the low fuel indicator illuminates in the IPC.
Unless you have a factory or professional type scan tool your better off taking your vehicle to a qualified repair shop.

Fuel Gage Inaccurate or Inoperative
Circuit/System Description
The fuel level sender changes resistance based on the fuel level. The engine control module (ECM) monitors the signal circuit of the fuel level sender to determine fuel level. When the fuel tank is full, the sender resistance is low and the ECM senses a low signal voltage. When the fuel tank is empty, the sender resistance is high and the ECM senses a high signal voltage. The ECM uses the signal circuit of the fuel level sender in order to calculate the remaining fuel level percent in the tank. The ECM sends the fuel level message via the serial data circuit to the body control module (BCM). The BCM sends the fuel level percent to the instrument panel cluster (IPC) via the serial data circuit for display on the fuel gage.

Circuit
Short to Ground
High Resistance
Open
Short to Voltage
Signal Performance
Fuel Level Sensor Signal
P0462
1
P0463, P0464
P0463
P0461
Fuel Level Sensor Low Reference
--
1
P0463, P0464
P0463
P0461
1. Fuel Gage Inaccurate or Inoperative

Do you know what a DTC is ? diagnostic trouble code !

Fuel Gauge Troubleshooting

Fuel Gage
The IPC displays the fuel level as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the fuel level percent. The fuel gage defaults to empty if:
• The PCM detects a malfunction in the fuel level sensor circuit.
• The IPC detects a loss of class 2 communications with the PCM.
When the fuel level is less than a pre-determined value, the CHECK GAGES indicator illuminates.
DTC P0462
The fuel level sensor changes resistance based on fuel level. The PCM monitors the signal circuit of the fuel level sensor in order to determine fuel level. When the fuel tank is full, the sensor resistance is high and the PCM senses a high signal voltage. When the fuel tank is empty, the sensor resistance is low and the PCM senses a low signal voltage. The PCM uses the signal circuit of the fuel level sensor in order to calculate the total remaining fuel (%) in the tank. The PCM sends the fuel level percent via the class 2 serial data circuit to the IPC in order to control the fuel gage. The fuel level information is also used for misfire and EVAP diagnostics
DTC P0463 (3.8L)

How to test fuel gauge tank sending unit P0463 GM

Cranks won't start , Did you check for spark ,fuel pressure ?
Radio Setup .Will the vehicle communicate with a scan tool ? Fuel an temp gauges not working are probably bad step motors inside the instrument cluster that controls the gauges . Where do the gauges read 0 or something else ?
Engine Coolant Temperature Gage
The IPC displays the engine coolant temperature as determined by the PCM. The body control module (BCM) receives a class 2 message from the PCM indicating the engine coolant temperature. The BCM converts the engine coolant temperature into a percent gage deflection. The IPC receives a message from the BCM via the serial peripheral interface (SPI) indicating the requested gage position. The engine coolant temperature gage defaults to 38°C (100°F) or below if:
?€¢
The PCM detects a malfunction in the engine coolant temperature sensor circuit.

?€¢
The BCM detects a loss of class 2 communications with the PCM.

?€¢
The IPC detects a loss of SPI communications with the BCM.

Fuel Gage
The IPC displays the fuel level as determined by the PCM. The body control module (BCM) receives a class 2 message from the PCM indicating the fuel level percent. The BCM converts the fuel level percent into a percent gage deflection. The IPC receives a message from the BCM via the serial peripheral interface (SPI) indicating the requested gage position. The fuel gage defaults to E (empty) if:
?€¢
The PCM detects a malfunction in the fuel level sensor circuit.

?€¢
The BCM detects a loss of class 2 communications with the PCM.

?€¢
The IPC detects a loss of SPI communications with the BCM.

When the fuel level is less than a pre-determined value, the low fuel indicator illuminates.
DTC P0462
The fuel level sensor changes resistance based on fuel level. The PCM monitors the signal circuit of the fuel level sensor in order to determine fuel level. When the fuel tank is full, the sensor resistance is high and the PCM senses a high signal voltage. When the fuel tank is empty, the sensor resistance is low and the PCM senses a low signal voltage. The PCM uses the signal circuit of the fuel level sensor in order to calculate the total remaining fuel in the tank. The PCM sends the fuel level percent via the class 2 serial data circuit to the body control module (BCM). The BCM converts this data and sends a fuel gage percent deflection to the IPC via the serial peripheral interface (SPI) in order to control the fuel gage. The fuel level information is also used for misfire and EVAP diagnostics.

Have
For the DE 100 series radio, complete the following procedure, using a scan tool, in order to properly set up communication:

1. At the Main Menu screen, select: Diagnostics.
2. At the Vehicle Identification screen, select the following options:
?€¢
Model Year



?€¢
Passenger Car


3. At the System Selection Menu screen, select: Body.
4. At the Vehicle Identification screen, select the Platform type.
5. At the Body screen, select: Radio.
6. At the Radio screen, select: Special Functions.
7. At the Special Functions screen, select: Radio Setup.
8. At the Radio Setup screen, press ENTER. The following test will set up a new or existing radio.
9. Select one of the following options:
?€¢
USA/Canada



?€¢
Export


10. Press the ENTER key.
11. Verify that the scan tool displays "Test in Progress."
12. Verify that the scan tool displays "Test Completed Successfully."
13. Press EXIT on the scan tool.

Important: The radio set up will configure the following systems:
?€¢
LEARN VIN

?€¢
Diagnostic Trouble Codes

?€¢
Class 2 Radio Messages

?€¢
Country Code

?€¢
Chime Volume

?€¢
Chime Level

?€¢
12/24 Hour Clock

Without learning the VIN, the radio will display a locked message (LOC).
The radio setup procedure will also clear the following messages:
?€¢
CAL

?€¢
CAL ERR

?€¢
CALIBRATE

Fuel Gage
The IPC displays the fuel level as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the fuel level percent. The fuel gage defaults to empty if:
• The PCM detects a malfunction in the fuel level sensor circuit.
• The IPC detects a loss of class 2 communications with the PCM.
When the fuel level is less than a pre-determined value, the low fuel indicator illuminates.

Hooking up a professional or factory scanner an checking input data to the PCM from the sending unit inside the fuel tank ,viewing the information sent to the IPC , Checking for diagnostic trouble code's .
DTC P0461
DTC P0462
Circuit Description
The fuel level sender changes resistance based on fuel level. The PCM monitors the signal circuit of the fuel level sender in order to determine fuel level. When the fuel tank is full, the sender resistance is high and the PCM senses a high signal voltage. When the fuel tank is empty, the sender resistance is low and the PCM senses a low signal voltage. The PCM uses the signal circuit of the fuel level sender in order to calculate the total remaining fuel percentage in the tank. The PCM sends the fuel level percent via the class 2 serial data circuit to the instrument cluster in order to control the fuel gage. The fuel level information is also used for misfire and EVAP diagnostics.

Install a scan tool.
Turn the ignition ON, with the engine OFF.
With a scan tool, observe the Fuel Tank Level Remaining parameter in the PCM data list.
Does the scan tool indicate that the Fuel Tank Level Remaining parameter is less than the specified value?
1%

No DTC'S - diagnostic trouble code's stored ,use this diagnostic procedure
Fuel Gage Inaccurate or Inoperative
• Refer to Fuel Level Specifications in order to verify the correct fuel level sensor readings. The Fuel Tank Level Remaining parameter is available in the scan tool in the PCM data list.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step tests for a high resistance in the signal circuit and the low reference circuit of the fuel level sensor.
DTCs will be set in the PCM when you perform this diagnostic table.
Step
Action
Value(s)
Yes
No
Schematic Reference: Instrument Cluster Schematics
1
Did you perform the Instrument Cluster Diagnostic System Check?
--
Go to Step 2
Go to Diagnostic System Check - Instrument Cluster
2
Disconnect C104.
Connect the J 33431-C Signal Generator and Instrument Panel Tester between the signal circuit of the fuel level sensor and the low reference circuit of the fuel level sensor on the male terminal side.
Turn the ignition ON, with the engine OFF.
Important: Verify the J 33431-C resistance settings with a DMM.
Vary the resistance on the J 33431-C from 40-250 ohms.
Refer to Fuel Level Specifications in order to convert from resistance to fuel gage display.
Does the fuel gage display the correct fuel level?

How to test fuel gauge tank sending unit P0463 GM

THERE SHOULD BE 3 WIRES, FROM PUMP/SENDER UNIT, 1 WIRE FOR PUMP POWER, 1 WIRE FOR GROUND, & 1 WIRE FOR FUEL GAGE, THE FUEL GAGE WIRE GOES DIRECTLY TO GAGE , INSPECT THIS WIRE , MAY CHANGE COLOR ON ITS WAY TO GAGE, WIRE MAY HAVE BEEN DAMAGED UNDER TRUCK, ALONG FRAME RAIL, OR HAS BECOME CORRODED, A BUMP IN THE WIRE INSULATION(CORROSION), ALSO, CHECK ALL GROUNDS, REPEAT, ALL GROUNDS TO FUEL PUMP CICUIT, EVEN IF THEY LOOK OK, THEY COULD BE BAD GROUNDS, YOU NEED GOOD GROUNDS TO COMPLETE ANY CIRCUIT !!! 2001 TRUCK, I'D QUESTION YOURS !!!!! WHAT SHAPE WAS YOUR WIRE HARNESS @ PUMP, THEY GO BAD, ANYTHING UNDER THE TRUCK !!!!!! STAY IN YOUCH, LIKE TO KNOW OUTCOME !

Either there is a short in the fuel sender wiring or the sender in the tank is bad.The actual gauge is rarely bad.Good luck.


Else The float affixed to your fuel pump in your gas tank is stuck.

It tells the dash you ALWAYS have a full tank.
You have to drop the tank, PB Blast/WD40 the float, get it to drop down.
Finally Your unit in the tank is bad. Pull it out and move it up and down while someone looks at the gauge. If doesn't work, buy a new one. They are not that expensive.

Change the fuel gage sender unit in tank.its faulty.

I took the vehicle to the Jeep dealership, and the problem went away before they could check it out. They are going to check wiriing next, because the check engine light went out on its own, and the fuel gage began working corectly on its own. Not sure what caused it, but hope to have an answer from the dealer.

You could have losen the wireharness from the tank to the frame, check along the frame towards the fuel tank and check for any loose connection. The only other thing is the sending unit in the tank it self may have gone bad. Good luck