DTC P0463 Fuel Level Sensor Circuit High Voltage. Geo Tracker - 2WD 1997

For 1990-2009 cars

Table 1: | Fuel Level Sensor Inspection

Engine Controls Schematics

### Circuit Description

The powertrain control module (PCM) uses the fuel level input from the fuel level sensor in order to calculate the expected vapor pressures within the fuel system. Vapor pressures vary as the fuel level changes. Vapor pressure is critical to determining if the EVAP control system is operating properly. Fuel level information is used in determining whether to run an EVAP control system diagnostic. A fuel level that is too high or too low may prevent the EVAP control system diagnostics from accurately detecting a fault.

### Conditions for Setting the DTC

• | Voltage range check: The voltage is greater than a specified value after extended driving.

• | Condition present for 0.5 seconds.

### Action Taken When the DTC Sets

• | The PCM illuminates the malfunction indicator lamp (MIL) after two consecutive ignition cycles in which the diagnostic runs with the fault active.

• | The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

• | The PCM will enter the Fail-Safe Function and operate as if the fuel level is full.

### Conditions for Clearing the MIL/DTC

• | The MIL turns OFF after three consecutively passing trips without a fault present.

• | A History DTC clears after 40 consecutive warm-up cycles without a fault.

• | Use the scan tool Clear DTC Information function or disconnect the PCM battery feed in order to clear the DTC.

### Diagnostic Aids

The scan tool will display a default value of 100% all the time when a fuel level sensor circuit DTC is present. Any current or stored fuel level sensor circuit DTCs (DTC P0463 or P0461) must be cleared before diagnosing the fuel level sensor circuit with a scan tool.

An open in the fuel level sensor circuit will indicate a 0% fuel level (empty fuel tank), while a short to ground in the fuel level sensor circuit will indicate a 100% fuel level (full fuel tank).

Check the resistance of the fuel level sensor at the following positions:

#### Fuel Level Sensor Inspection

Fuel Level Position | Resistance Measurement
--- | ---
Full Tank | 10 ohms less
Half Tank | 30 to 35 ohms
Empty Tank | 100 ohms or more

Check for a faulty electrical connection at the PCM.

An intermittent malfunction may be caused by a problem in the fuel level sensor electrical circuit. Inspect the wiring harness and components for any of the following conditions:

• | Backed out terminals.

• | Improper mating of terminals.

• | Broken electrical connector locks.

• | Improperly formed or damaged terminals.

• | Faulty terminal to wire connections.

• | Physical damage to the wiring harness.

• | A broken wire inside the insulation.

• | Corrosion of electrical connections, splices, or terminals.

If the DTC P0463 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.

### Test Description

The numbers below refer to the step numbers in the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. This step determines if a fault is present. Review the Freeze Frame data in order to determine when the DTC set. Always record this information.

3. This step checks the circuit from the fuel level sensor to the PCM. Because the scan tool will display a default value of 100% all the time when a fuel level sensor circuit DTC is present, any current or stored fuel level sensor circuit DTCs (DTC P0463 or P0461) must be cleared before reading the fuel level parameter on the scan tool.

4. Checks for a faulty fuel level sensor.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check

2

1. Turn ON the ignition, leaving the engine OFF.
2. Clear the scan tool information.
3. Operate vehicle within the Freeze Frame conditions as specified.

Is a DTC P0463 set?

--

Go to Step 3

Go to Diagnostic Aids

3

1. Disconnect the fuel level sensor harness connector C400 which is located at the rear of the vehicle behind the left tail light assembly.
2. Turn ON the ignition, leaving the engine OFF.
3. Measure the signal voltage from the fuel level sensor connector YEL/RED wire (PCM side), using a DMM.

Is the voltage near the specified value?

7-8 volts

Go to Step 4

Go to Step 8

4

1. Reconnect the fuel level sensor harness connector C400.
2. Remove the fuel tank from vehicle. Refer to Fuel Tank Replacement .
3. Disconnect the fuel level sensor electrical connector at the fuel level sensor.
4. Measure the signal voltage from the fuel level sensor connector, YEL/RED wire (PCM side), using the DMM.

Is the voltage near the specified value?

7-8 volts

Go to Step 5

Go to Step 9

5

1. Check for a proper ground connection at the fuel tank.
2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 15

Go to Step 6

6

Important: In order to avoid an incorrect fuel level reading on the scan tool, any current or stored fuel level DTCs should be cleared.

1. Remove the fuel tank level sensor from the fuel tank.
2. Reconnect the fuel tank level sensor electrical connector.
3. Clear the scan tool information.
4. Monitor the fuel tank level parameter on the scan tool while moving the fuel tank sensor float from the empty position and then back to the full position. Repeat the procedure several times.

Does the fuel tank level value on the scan tool increase and then decrease steadily when the float is swept from one end to the other?

--

Go to Diagnostic Aids

Go to Step 7

7 | Important: The fuel gauge responds slowly to changes in the position of the fuel sensor float. Continue to move the fuel tank sensor float from the empty position and then back to the full position while observing the fuel gauge on the I/P. Does the I/P fuel gauge indicate a full and an empty fuel tank when the float is swept from one end to the other? | -- | Go to Step 13 | Go to Step 10

8

1. Check for an open or a short in the fuel level sensor signal wire between the harness connector C400 and the PCM.
2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 15

Go to Step 11

9 | Repair the open or the short in the fuel level sensor signal wire between the fuel level sensor harness connector C400 and the fuel level sensor. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 15 | --
10 | Replace the fuel level sensor. Refer to Fuel Level Sensor Replacement . Is the action complete? | -- | Go to Step 15 | --

11

1. Turn OFF the ignition.
2. Disconnect fuel level sensor harness.
3. Disconnect the PCM electrical connector.
4. Turn ON the ignition, leaving the engine OFF.
5. Measure the voltage from the fuel level sensor signal (input) terminal (harness side), using a DMM

Does the DMM read within the specified value?

7-8 volts

Go to Step 14

Go to Step 12

12

1. Check for an open or a short in the fuel level sensor signal circuit between the PCM and the I/P fuel gauge.
2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 15

Go to Instrument Cluster Diagnosis

13 | Check for an open in the fuel level sensor signal circuit between the PCM and the I/P fuel gauge. Refer to Wiring Repairs in Wiring Systems. Was a repair necessary? | -- | Go to Step 15 | Go to Step 14
14 | Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | Go to Step 15 | --

15

1. Perform the scan tool Clear DTC Information function and road test the vehicle within the Freeze Frame conditions that set the DTC.
2. Review the scan tool data and check for DTCs. The repair is complete if no DTCs are stored .

Are any DTCs displayed on the scan tool?

--

Go to the Applicable DTC Table

System OK