Guys, I have a 98 vette and the fuel guage quit working. I read all the threads you had posted. Tried the tetron and seafoam with no help. I removed the drivers side sensor and found its contact board was worn away. Replaced with new one and checked its operation before I put tire on and it worked. Then I put tire on and went for a ride. Before I got out of the driveway the guage quit. It has code P0463 (high voltage). Will reset for 30 sec. and guage works then P0463 returns. Is this a ground problem or has anyone had this and what is the remedy?
Thanks
Charlie

 

There is also a sensor on the passenger side.

 

You have an issue with the driver side sensor circuit, not the passenger side. Since you just put in a new sensor I suspect a circuit issue. Inspect the sensor connector pins and also make sure the ground is good also.

Could also be a connector issue at the PCM and hopefully not a PCM issue itself.

Not at home now with my info. Here is a general description of the code and I think it is for a 1998 or 1999. I can verify it is 99 or get the 99 info later. This will give you some insight.


DTC P0463 Fuel Level Sensor Circuit High Voltage

Circuit Description
The left Fuel Level sensor, mounted in the rear side of the left fuel tank, measures fuel level changes within the left fuel tank. The left Fuel Level Sensor changes resistance based on fuel level. The Fuel Level Sensor has a signal circuit and a ground circuit. The PCM applies a voltage (about 5.0 volts) on the signal circuit to the sensor. The PCM monitors changes in this voltage caused by changes in the resistance of the sensor to determine fuel level.

When the fuel tank is full, the sensor resistance is high, and the PCMs signal voltage is only pulled down a small amount through the sensor to ground. Therefore, the PCM will sense a high signal voltage (fuel tank full). When the fuel tank is empty, the sensor resistance is low, and the signal voltage is pulled down a greater amount. This causes the PCM to sense a low signal voltage (fuel tank empty).

The PCM uses inputs from the Fuel Level Sensor to calculate the total fuel remaining in the fuel tank(s). This information is then sent to the fuel gauge.

When the PCM senses a signal voltage higher than the normal operating range of the sensor, this DTC sets.

The following is a description on how the fuel pump/system functions: An electric high pressure fuel pump attaches to the fuel sender assembly inside the left fuel tank. The fuel pump pumps fuel to the fuel rail assembly at a specified flow and pressure. Excess fuel from the fuel rail assembly returns to the left fuel tank through the return pipe. The fuel pump delivers a constant flow of fuel to the engine even during low fuel conditions and aggressive vehicle maneuvers. The PCM controls the electric fuel pump operation through a fuel pump relay.

The left tank fuel pump also supplies a small amount of pressurized fuel to the right fuel tank siphon jet pump through the fuel feed rear crossover pipe. The pressurized fuel creates a venturi action inside the siphon jet pump. The venturi action causes the fuel to be drawn out of the right fuel tank. Fuel is then transferred from the right fuel tank to the left fuel tank through the fuel sender fuel feed pipe. The fuel system is designed to maintain a greater level in the left fuel tank then the right fuel tank when the electric fuel pump is operating. The fuel transfer rate from the left fuel tank to the right fuel tank is less than the transfer rate from the right fuel tank to the left fuel tank. Therefore, with the electric fuel pump operating, the left fuel tank level should be higher than the right fuel tank level.

The fuel level in the fuel tanks equalize when the following occur:

The electric fuel pump is not operating.
The fuel level is greater than 50%.
Conditions for Running the DTC
Engine Running

Conditions for Setting the DTC
Fuel Level Sensor voltage is above 2.9 volts
Conditions met for 50 seconds
Action Taken When the DTC Sets
The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.
The malfunction indicator lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
Conditions for Clearing the DTC
A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
Use a scan tool in order to clear the DTC.
Diagnostic Aids

Important
The PCM terminals C1-24 and C2-24 are the Sensor Ground Jumper terminals. This DTC sets if the jumper is open or the connection between the jumper and the PCM is faulty. Inspect for proper terminal tension/connections at the PCM harness connector before replacing the PCM.
Depending on the current fuel level, it may be difficult to locate a malfunctioning sending unit. The malfunction may only occur when the fuel level is full or near empty. The fuel sending unit may need to be removed for further diagnosis. A Fuel Level sensor that has an intermittent condition causes this DTC to set. Remove the Fuel Level sensor refer to Fuel Sender Assembly Replacement in order to check the resistance of the sensor. The resistance of the sensor should change smoothly from 40ohms to 250ohms. Replace the sensor if the resistance did not change smoothly or was out of range.
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.

The voltages in the Fuel Level Conversion Table are approximate values. Use this table to aid in diagnosis.

Fuel Level Conversion Table

Approximate Values

Fuel Level
Left Tank voltage
Right Tank Voltage

100 %
2.5 V
2.5 V

75 %
2.5 V
1.5 V

50 %
2.5 V
Less than 1.0 V

25 %
1.7 V
Less than 1.0 V

0 %
Less than 1.0 V
Less than 1.0 V


The following occurs with this DTC set:

The vehicle fuel gauge displays empty.
The Check Gauge lamp illuminates.
The Driver Information Center displays a message.
Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.

 

I thank each of you for your help. Dadaroo's description of operation leads me to believe I have a grounding issue. I am out of town at the moment but will let you know when I find the problem. Was that description in a shop manual? If so, I know what my next purchase will be. Thanks again for your reply's.
Charlie

 

Yes, it is from the factory service manual. The manual also has a separate diagnostic procedure but it relies heavily on the use of a Tech II.

Here is some more info in the interim, I can provide more as needed:





Fuel Senders


G401 left rear outer frame


G401: Splice pack SP400:
Fuel pump & sender assembly, left
Fuel level sender, right
Tail, stop, turn signal, rear left
Tail, stop, turn signal, rear right
Center high mounted stop lamp
Backup lamp, right
Backup lamp, left
License lamp, right rear
License lamp, left rear
Marker lamp, left rear
Marker lamp, right rear

 

Thanks again!
Charlie

 

Sent you a PM you may like. Let me know if you don't get it.

Mr. Sam

 

Sorry, thought you had a 99. Your 98 would have the same design as the 97 in the above schematic. Primarily a change in the passenger side sender.

 

The problem with my gauge was in the plug on the inside of the new sensor that I had just replaced. It had a push to penetrate the wire type plug. I did not check continuity when I first installed it. Volt/Ohm meters are amazing if we will just use them.
Thanks again guys.