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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Express (CNG) 🢒 Engine 🢒 Engine Controls - 6.0L 🢒 DTC P0193

DTC P0193 w/o JL4

Circuit Description

The fuel rail pressure (FRP) sensor is a pressure sensor. The fuel injector control module (FICM) supplies about 5 volts on the FRP sensor reference voltage circuit. The FICM 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 FICM monitors the FRP sensor voltage and communicates the data to the powertrain control module (PCM) by a dedicated pulse width modulated (PWM) circuit.

This DTC sets when the FRP sensor signal voltage is more than the normal operating range of the sensor.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0193 Fuel Rail Pressure Sensor Circuit High Voltage

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC
    • The FRP sensor signal voltage is more than 5 volts.
    • The condition exists for at least 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.

  1. This step determines if the condition is present.

    2.

  2. This step determines if an open sensor ground circuit condition the cause of the condition. The fuel rail temperature (FRP) and the FRT share a sensor ground. An open circuit between the splice and the FICM will cause both signal circuits to indicate a high voltage.

    3.

  3. This step determines if an open or shorted signal circuit is the cause of the condition.

    4.

  4. This step determines if a shorted 5-volt reference circuit is the cause of the condition.

    5.

  5. 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.

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)

2

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the fuel rail pressure (FRP) data display with a scan tool.

Does the scan tool display the FRP sensor voltage more than the specified value?

5 V

Go to Step 4

Go to Step 3

3
  1. Observe the Freeze Frame and/or the Failure records data for this DTC.
  2. Turn the ignition OFF for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame and/or the Failure records data.

Does the DTC fail this ignition cycle?

--

Go to Step 4

Go to Intermittent Conditions

4

Observe the fuel rail temperature (FRT) sensor data display with a scan tool.

Does the scan tool display the FRT sensor voltage more than the specified value?

4.7 V

Go to Step 8

Go to Step 5

5

  1. Disconnect the FRP sensor.
  2. Connect a 3-amp fused jumper wire between the signal circuit of the FRP sensor and a known good ground.

    3. Important: If the jumper fuse opens, repair the signal circuit short to battery voltage.

  3. Observe the FRP sensor data display with a scan tool.

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

6

  1. Remove the jumper.
  2. Measure the voltage from the 5-volt reference circuit of the FRP sensor with a DMM.

Does the DMM display a voltage more than the specified value?

5.2 V

Go to Step 7

Go to Step 10

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 fuel injector control module (FICM) and the splice. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 12

9

Test the signal circuit of the FRP sensor for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 16

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 G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 15

11

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 G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 14

12

Inspect for proper terminal contact at the harness connector of the FICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 15

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 G/H Van Service Manual.

Did you complete the repair?

--

Go to Step 16

--

14

Replace the (FRP) sensor. Refer to Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15

Replace the FICM. Refer to Fuel Injector Control Module Replacement .

Did you complete the replacement?

--

Go to Step 16

--

16
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Turn ON the ignition, with the engine OFF.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 17

17

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK

DTC P0193 JL4

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.

This DTC sets when the FRP sensor signal voltage is more than the normal operating range of the sensor.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0193 Fuel Rail Pressure Sensor Circuit High Voltage

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC
    • The FRP sensor signal voltage is more than 5 volts.
    • The condition exists for at least 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.

  1. This step determines if the condition is present.

    2.

  2. This step determines if a shorted signal circuit is the cause of the condition.

    3.

  3. This step determines if a shorted 5-volt reference circuit is the cause of the condition.

    4.

  4. This step determines if an open sensor ground circuit 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)

2

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the fuel rail pressure (FRP) data display with a scan tool.

Does the scan tool display the FRP sensor voltage more than the specified value?

5 V

Go to Step 4

Go to Step 3

3
  1. Observe the Freeze Frame and/or the Failure records data for this DTC.
  2. Turn the ignition OFF for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame and/or the Failure records data.

Does the DTC fail this ignition cycle?

--

Go to Step 4

Go to Intermittent Conditions

4

  1. Disconnect the FRP sensor.
  2. Observe the FRP sensor data display with a scan tool.

Does the scan tool display the FRP sensor voltage less than the specified value?

0.45 V

Go to Step 5

Go to Step 8

5

Measure the voltage from the 5-volt reference circuit of the FRP sensor with a DMM.

Does the DMM display a voltage more than the specified value?

5.2 V

Go to Step 9

Go to Step 6

6

Probe the ground circuit of the FRP sensor with a test lamp connected to B+.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 7

7

Test the ground circuit of the FRP sensor for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 11

8

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 G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

9

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 G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

10

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 G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 12

11

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 G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

12

Replace the (FRP) sensor. Refer to Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement .

Did you complete the replacement?

--

Go to Step 14

--

13

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L in the G/H Van Service Manual.

Did you complete the replacement?

--

Go to Step 14

--

14
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Turn ON the ignition, with the engine OFF.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 15

15

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK