DTC P0193. GMC Truck GMC T-Series Medium Duty Truck F6/F7/F8 2004

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2004 🢒 GMC T-Series Medium Duty Truck F6/F7/F8 🢒 DTC 🢒 DTC P0193

DTC P0193 Without RPO CTF

Circuit Description

The engine control module (ECM) monitors the fuel rail pressure via a fuel rail pressure (FRP) sensor. When the fuel rail pressure is high the signal voltage is high. When the fuel rail pressure is low the signal voltage is low. If the fuel rail pressure is above the upper limit for the sensor, DTC P0193 will set.

Conditions for Running the DTC

•	DTCs P0641 or P0651 are not set.

•	The ignition is ON.

•	The system is not in Powerdown Mode.

Conditions for Setting the DTC

The ECM detects the signal circuit is more than 185 MPa.

Action Taken When the DTC Sets

•	The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

•	The control module limits fuel injection and fuel rail pressure.

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.

•	Clear the MIL and the DTC with a scan tool.

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics
1	Did you perform the Diagnostic System Check-Engine Controls?	--	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Turn ON the ignition, with the engine OFF. Observe the Actual Fuel Rail Pressure parameter with a scan tool. Does the scan tool indicate that the Actual Fuel Rail Pressure is within the specified range?	1.2-1.9 MPa	Go to Step 4	Go to Step 3
3	Disconnect the FRP sensor connector. Probe the FRP 5-volt reference circuit with a DMM connected to a good ground. Refer to Troubleshooting with a Digital Multimeter in Wiring Systems. Does the voltage measure near the specified value?	5 V	Go to Step 5	Go to Step 4
4	Test the 5-volt reference circuit of the FRP sensor for a short to voltage, high resistance, or an open. Refer to Testing for Continuity , Testing for Short to Ground or Testing for a Short to Voltage in Wiring Systems. Repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 15	Go to Step 12
5	Verify that the ignition is ON, with the engine OFF. Verify the FRP sensor harness connector is still disconnected. Measure the current between the FRP sensor signal circuit and ground circuit at the FRP harness connector with a DMM. Does the current measure more than the specified value?	0.025 mA	Go to Step 8	Go to Step 6
6	Turn OFF the ignition. Disconnect the negative battery cables. Measure the resistance from the low reference circuit of the FRP sensor to a good ground. Does the resistance measure less than the specified value?	5 ohms	Go to Step 7	Go to Step 10
7	Turn OFF the ignition. Connect a 3-amp fused jumper wire between the signal circuit of the FRP sensor and the low reference circuit of the FRP sensor. Refer to Using Fused Jumper Wires in Wiring Systems. Turn ON the ignition, with the engine OFF. With a scan tool, observe the Actual FRP parameter. Does the scan tool indicate that the Actual FRP parameter is at the specified value?	0.0 MPa	Go to Step 11	Go to Step 9
8	Check for a short to voltage 12-volt or 5-volt reference on the FRP sensor signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 15	Go to Step 14
9	Test the signal circuit of the FRP sensor for a high resistance or an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you Find and correct the condition?	--	Go to Step 15	Go to Step 12
10	Disconnect the ECM. Test the low reference circuit of the FRP sensor for a high resistance or an open. Refer to Testing for Continuity in Wiring Systems. Did you find and correct the condition?	--	Go to Step 15	Go to Step 12
11	Inspect for poor connections at the harness connector of the FRP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 15	Go to Step 13
12	Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 15	Go to Step 14
13	Replace the FRP sensor. Did you complete the replacement?	--	Go to Step 15	--
14	Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data . Did you complete the replacement?	--	Go to Step 15	--
15	Use the scan tool in order to clear the DTCs. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC run and pass?	--	Go to Step 16	Go to Step 2
16	With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed?	--	Go to Diagnostic Trouble Code (DTC) List	System OK

DTC P0193 With RPO CTF

Circuit Description

The fuel rail pressure sensor is installed to the fuel rail. The fuel rail pressure detects the fuel pressure in the fuel rail, converts the pressure into a voltage signal, and sends the signal to the engine control module (ECM). The fuel rail pressure sensor has the following circuits:

•	A 5-volt reference circuit

•	A low reference circuit

•	A fuel rail pressure sensor signal circuit

The ECM supplies 5 volts to the fuel rail pressure sensor on the 5-volt reference circuit. The ECM also provides a ground on the low circuit. Higher fuel rail pressure provides higher fuel pressure sensor voltage, while lower pressure provides lower fuel pressure sensor voltage. The ECM calculates the actual fuel rail pressure, fuel pressure, from the voltage signal, and uses the result in fuel injection control and other control tasks. The ECM monitors the fuel rail pressure sensor signal for voltage outside the normal range. If the ECM detects an excessively high fuel rail pressure sensor signal voltage, this DTC will set.

Conditions for Running the DTC

•	The ignition switch is ON.

•	The battery voltage is between 10-16 volts.

Conditions for Setting the DTC

The ECM detects that the fuel rail pressure sensor signal voltage is more than 4.7 volts.

Action Taken When the DTC Sets

•	The ECM illuminates the malfunction indicator lamp (MIL) and Reduced Engine Power indicator lamp, if fitted, when the diagnostic runs and fails.

•	The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.

•	The ECM limits the fuel injection quantity for fail-safe operation.

•	The ECM limits the desired fuel rail pressure for fail-safe operation.

•	The ECM closes the exhaust gas recirculation (EGR) valve and holds the EGR valve to a closed position.

•	The ECM inhibits cruise control.

Condition for Clearing the DTC

•	A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

•	Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

•	If an intermittent condition is suspected, the following may cause an intermittent:

-	Poor connections

-	A misrouted harness

-	Rubbed through wire insulation

-	Broken wire inside the insulation

•	Inspect for the following conditions:

-	Poor connection at ECM--Inspect the harness connectors for the following conditions:

•	Backed-out terminals

•	Improper mating

•	Broken locks

•	Improperly formed or damaged terminals

•	Poor terminal to wire connection

-	Damaged harness--Inspect the wiring harness for damage. If the harness appears to be OK, observe the Engine Coolant Temperature display on the scan tool while moving the connectors and the wiring harness related to the sensor. A change in the display will indicate the location of the fault.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Did you perform the Diagnostic System Check - Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Observe the failure Records for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
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 3

Go to Diagnostic Aids

Start the engine.
Monitor the DTC Information with a scan tool.

Is DTC P0641 also set?

Go to DTC P0641

Go to Step 4

Turn OFF the ignition.
Disconnect the fuel pressure sensor connector.
Connect a DMM between the 5-volt reference circuit and the low reference circuit of the fuel pressure sensor.
Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified range?

4.5-5.5 V

Go to Step 6

Go to Step 5

Turn OFF the ignition.
Disconnect the fuel rail pressure sensor connector.
Connect a DMM between the 5-volt reference circuit and a known good ground.
Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified range?

4.5-5.5 V

Go to Step 10

Go to Step 9

Turn OFF the ignition.
Disconnect the fuel pressure sensor connector.
Connect a DMM between the signal circuit and the low reference circuit of the fuel pressure sensor.
Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified range?

4.5-5.5 V

Go to Step 7

Go to Step 8

Important: The fuel pressure sensor may be damaged if the circuit is shorted to a voltage source.

Test the signal circuit between the engine control module (ECM) and the fuel pressure sensor for a short to ground circuit.
Repair the circuit, as necessary.

Did you find and correct the condition?

Go to Step 15

Go to Step 14

Test the signal circuit between the ECM and the fuel pressure sensor for the following conditions:

•	An open circuit

•	High resistance

Repair the circuit, as necessary.

Did you find and correct the condition?

Go to Step 15

Go to Step 11

Test the 5-volt reference circuit between the ECM and the fuel pressure sensor for the following conditions:

•	An open circuit

•	High resistance

Repair the circuits, as necessary.

Did you find and correct the condition?

Go to Step 15

Go to Step 12

Test the low reference circuit between the ECM and the fuel pressure sensor for the following conditions:

•	An open circuit

•	High resistance

Repair the circuits, as necessary.

Did you find and correct the condition?

Go to Step 15

Go to Step 12

Turn OFF the ignition.
Disconnect the fuel pressure sensor connector.
Inspect for poor connections at the harness connector of the fuel pressure sensor.
Repair the connections, as necessary.

Did you find and correct the condition?

Go to Step 15

Go to Step 13

Turn OFF the ignition.
Disconnect the ECM.
Inspect for poor connections at the harness connector of the ECM.
Repair the connections, as necessary.

Did you find and correct the condition?

Go to Step 15

Go to Step 14

Replace the fuel pressure sensor.

Did you complete the replacement?

Go to Step 15

Important: The new ECM must be programmed.

Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data .

Did you complete the replacement?

Go to Step 15

Clear the DTCs with a scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
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 16

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