Circuit Description
Important: The fuel level sensor referenced in this DTC refers to the left fuel level sensor for Y car.
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 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 PCM's 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.
Conditions for Setting the DTC
| • | The Fuel Level Sensor voltage is above 2.9 volts. |
| • | The above condition present for greater than 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
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. |
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.
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.
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
-
This step determines if the fault is present.
-
Using the 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 help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine 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. For an intermittent condition, refer to Symptoms .
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check ? | -- | ||
2 |
Did DTC P1639 Fail This Ignition cycle? | -- | ||
Is the Fuel Level Sensor voltage above the specified value? | 2.9 V | |||
Does the scan tool indicate that this diagnostic failed this ignition? | -- | Refer to Diagnostic Aids | ||
5 |
Is the Fuel Level sensor voltage below the specified value? | 2.9 V | ||
6 | Jumper the Fuel Level sensor signal circuit to a known good ground. Is the Fuel Level sensor voltage below the specified value? | 2.9 V | ||
7 |
Is the Fuel Level sensor signal circuit open? | -- | ||
8 | Repair the Fuel Level sensor signal circuit. Refer to Body and Accessories/Wiring Systems. Is the action complete? | -- | -- | |
9 |
Is the Fuel Level sensor ground circuit open? | -- | ||
10 | Replace the Fuel Level sensor. Refer to Fuel Sender Assembly Replacement . Is the action complete? | -- | -- | |
11 | Repair the Fuel Level sensor ground circuit. Refer to Body and Accessories/Wiring Systems. Is the action complete? | -- | -- | |
12 |
Did you find and correct the condition? | -- | ||
13 |
Important: Program the replacement PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement . Replace the PCM. Is the action complete? | -- | -- | |
14 |
Does the scan tool indicate that this test ran and passed? | -- | ||
15 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
