Circuit Description
The fuel rail pressure (FRP) sensor is a pressure sensor. The powertrain control module (PCM) supplies about 5 volts on the FRP sensor reference voltage circuit. The PCM also supplies a ground circuit and a signal circuit to the FRP sensor. When the fuel rail pressure is normal, the FRP signal voltage rises to near 2.5 volts. If the fuel rail pressure increases, the FRP signal voltage increases. The PCM uses the FRP sensor information in order to adjust fuel trim.
This DTC sets when the FRP sensor signal voltage is more than the normal operating range of the sensor.
Conditions for Running the DTC
| • | The engine speed is more than 100 RPM. |
| • | DTC P0191 is not set. |
Conditions for Setting the DTC
| • | The FRP sensor signal voltage is more than 4.95 volts. |
| • | The condition exists for at least 2.5 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. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step determines if the condition is present.
-
This step determines if an open sensor ground circuit condition the cause of the condition. The FRP sensor and the gasoline fuel tank pressure (FTP) sensor share a sensor ground. An open circuit between the splice and the PCM will cause both signal circuits to indicate a high voltage.
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This step determines if a shorted signal circuit is the cause of the condition.
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This step determines if a shorted 5-volt reference circuit is the cause of the condition.
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This step determines if an open sensor ground circuit between the harness connector of the FRP sensor and the splice is the cause of the condition.
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The Fuel System Diagnosis procedure will determine if incorrect fuel pressure or the FRP sensor is the cause of the condition.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check Alternative Fuels - Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Alternative Fuels (Engine Controls) |
Does the scan tool display the FRP sensor voltage more than the specified value? | 4.9 V | Go to Step 4 | Go to Step 3 | |
3 |
Does the DTC fail this ignition cycle? | -- | Go to Step 4 | Go to Intermittent Conditions |
Observe the gasoline fuel tank pressure (FTP) data display with a scan tool. Does the scan tool display the FTP sensor voltage more than the specified value? | 4 V | Go to Step 8 | Go to Step 5 | |
Does the scan tool display the FRP sensor voltage less than the specified value? | 0.05 V | Go to Step 6 | Go to Step 9 | |
Does the DMM display a voltage more than the specified value? | 5.2 V | Go to Step 10 | Go to Step 7 | |
Probe the ground circuit of the FRP sensor with a test lamp connected to B+. Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 13 | |
8 | Test the ground circuit of the FRP sensor for an open between the PCM and the splice. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
9 | Test the signal circuit of the FRP sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
10 | Test the 5-volt reference circuit of the FRP sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 |
Inspect for proper terminal contact at the harness connector of the FRP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the C/K Pickup Service Manual. Did you find and correct the condition? | -- | Go to Step 15 | Go to Fuel System Diagnosis | |
12 | Inspect for proper terminal contact at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the C/K Pickup Service Manual. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 |
13 | Repair the ground circuit of the FRP sensor for an open, or high resistance, between the harness connector of the FRP sensor and the splice. Refer to Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual. Did you complete the repair? | -- | Go to Step 15 | -- |
14 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
15 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 16 |
16 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
