Refer to Engine Controls Schematics
PCM Fuel Tank Inputs
.
Circuit Description
The powertrain control module (PCM) requires an accurate indication of fuel level for evaporative emission (EVAP) system diagnosis. The fuel level in the fuel tank changes the rate of vacuum decay for the EVAP system leak diagnostics.
The fuel level sensor changes resistance based on fuel level. The fuel level sensor has a signal circuit and a ground circuit. The PCM applies about 5 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 signal voltage is only pulled down a small amount through the sensor to ground. Therefore, the PCM will sense a high signal voltage, or a full fuel tank. 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, or an empty fuel tank.
The PCM uses the input from the fuel level sensor to calculate the fuel level in the fuel tank. Fuel level data is used in the EVAP system diagnostics. Fuel level data is also sent to the instrument panel cluster (IPC) via serial data.
Conditions for Running the DTC
| • | DTC P0601 is not set. |
| • | Vehicle speed is more than 5 km/h. |
Conditions for Setting the DTC
The PCM detects a fuel level sensor signal below the normal operating range.
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. |
The PCM uses a fuel remaining value of 40 percent for the EVAP system diagnostic tests.
Conditions for Clearing the MIL/DTC
| • | 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. |
| • | The current DTC will clear when the diagnostic runs and does not fail. |
| • | Use a scan tool in order to clear the MIL diagnostic trouble code. |
| • | Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module Description , Clearing Diagnostic Trouble Codes. |
Diagnostic Aids
Notice: Use the connector test adapter kit J 35616-A for any test that
requires probing the following items:
• The PCM harness connectors • The electrical center fuse/relay cavities • The component terminals • The component harness connector
Important: Fuel level is used in EVAP system diagnosis. Always diagnose the fuel level sensor before any other EVAP system components or DTCs.
If the fuel level sensor is suspected of being stuck or inaccurate, refer to Fuel Level Sensor Diagnosis .If the problem is intermittent, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Monitor the Fuel Level display on the scan tool. Is the scan tool Fuel Level within the specified range? | 1-100% | |||
3 |
Does the scan tool indicate that this DTC failed this ignition? | -- | Go to Diagnostic Aids | |
4 | Is the fuel level parameter stuck high? | -- | ||
5 |
Important: Make sure there is an adaquate amount of fuel in the tank. Even with the fuel level at 0 percent, there may be enough fuel in reserve to run the vehicle. If adding fuel causes the fuel level to indicate above 0 percent, the fault is not currently present. If this is the case, refer to Diagnostic Aids.
Is the scan tool fuel level above the specified value? | 100% | ||
6 |
Was a problem found and corrected? | -- | ||
7 |
Is the voltage near the specified value? | 5V | ||
8 | Measure the voltage between the fuel level signal circuit and the sensor ground circuit. Is the voltage near the specified value? | 5V | ||
9 | Jumper the signal circuit to the ground circuit. Is the scan tool Fuel Level at the specified value? | 0% | ||
10 | Check for poor connections and/or terminal tension at the fuel sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Was a problem found and corrected? | -- | ||
11 | Repair the open or short to voltage in the fuel level sensor signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
12 | Repair the open fuel level sensor ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
13 | Replace the fuel level sensor. Refer to Fuel Level Sensor Replacement . Is the action complete? | -- | -- | |
14 | Check for poor connections and/or terminal tension at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Was a problem found and corrected? | -- | ||
15 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
16 |
Does the scan tool indicate that this test ran and passed? | -- | ||
17 | Review Captured Info using the scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to the applicable DTC table
| System OK |
