Circuit Description
The powertrain control module (PCM) provides 5 volts to the fuel tank pressure (FTP) sensor. The PCM monitors the voltage on the 5-volt reference circuit. If the voltage is out of tolerance, DTC P0651 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0651 5-Volt Reference 2 Circuit
Conditions for Running the DTC
| • | The engine is running. |
| • | DTC P0651 runs continuously when the above condition is met. |
Conditions for Setting the DTC
The PCM detects a voltage out of tolerance condition on the 5-volt reference 2 circuit for more than 2 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
3 |
Is the voltage less than the specified value? | 0.3 V | Go to Step 4 | Go to Step 10 |
4 | Measure the voltage from the 5-volt reference circuit of the FTP sensor to a good ground with the DMM. Is the voltage within the specified range? | 4.8-5.2 V | Go to Step 5 | Go to Step 7 |
5 |
Does the scan tool indicate that the DTC failed the last test? | -- | Go to Step 12 | Go to Step 6 |
6 |
Does the scan tool indicate that the DTC failed the last test when the FTP is connected? | -- | Go to Step 11 | Go to Testing for Intermittent Conditions and Poor Connections |
7 | Does the voltage measure more than the specified value? | 5 V | Go to Step 8 | Go to Step 9 |
8 | Test for a short to voltage on the 5-volt reference circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
9 | Test the 5-volt reference circuit for a short to ground or any low reference circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
10 | Repair the short to voltage in the FTP sensor signal circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 13 | -- |
11 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
12 | Replace the powertrain control module (PCM). Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 |
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
