DTC 67 Fuel Pressure Sensor Circuit High Voltage. GMC Truck GMC C Pickup

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC C Pickup - 2WD (CNG) 🢒 Engine 🢒 Engine Controls - 5.0L and 5.7L 🢒 DTC 67 Fuel Pressure Sensor Circuit High Voltage

Handling Electrostatic Discharge Sensitive Parts Notice
Handling Electrostatic Discharge Sensitive Parts Notice
CNG Fuel Controls
Engine Controls Components
OBDII Symbol Description Notice

Circuit Description

The fuel pressure sensor (FPS) supplies the ECU with a variable voltage signal from 0.5 volts to 4.5 volts that changes relative to fuel pressure. The FPS voltage varies from about 0.5 volts at 0 kPa (0 psi) to 4.1 volts at 24 820 kPa (3,600 psi). This is a type A DTC.

Conditions for Setting the DTC

The following conditions will set the DTC:

•	The ignition is ON.

•	The FPS voltage is less than 0.25 volt.

Action Taken When the DTC Sets

The ECU will set DTC 67 and illuminate the MIL after one fault has occurred.

Conditions for Clearing the MIL/DTC

The ECU turns the MIL OFF after three consecutive driving trips without a fault condition present. A DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 40°C (72°F) from the start-up coolant temperature, and the coolant temperature exceeds 70°C (160°F) during that same ignition cycle, or the code clearing procedure has been used.

Diagnostic Aids

When a DTC 67 sets, a short to ground in the FPS circuit is indicated. Always inspect any circuitry that is suspected of causing an intermittent complaint for the following conditions:

•	Backed out terminals

•	Improper mating

•	Broken locks

•	Improperly formed or damaged terminals

•	A poor terminal-to-wire connection

•	A damaged harness

Important: The fuel gauge will display the dormant fuel level for 10 seconds and then return to normal operation when the fuel gauge selector switch is depressed.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

This step verifies that the fault is present.

This step inspects the sensor reference voltage.

This step inspects the sensor ground circuit.

DTC 67 -- Fuel Pressure Sensor Circuit Low Voltage (1998 Only)

Step

Action

Value(s)

Yes

Was the Alternative Fuels (AF) Powertrain On-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to Alternative Fuels (AF) Powertrain On Board (OBD) System Check

Start the engine.
Allow the engine to idle for 15 seconds.
Turn the ignition OFF for 10 seconds.
Start the engine.
Allow the engine to idle for 15 seconds.
Turn the ignition OFF.
Retrieve the codes from the AF ECU.

Was DTC 67 retrieved?

Go to Step 3

Go to Intermittent Conditions

Backprobe the fuel pressure sensor (FPS) signal circuit in ECU (blue) connector C001 using a DVOM.

Is the voltage below the specified value?

0.25 V

Go to Step 4

Go to Step 11

Disconnect the FPS connector C315.
Turn ON the ignition.
Inspect for voltage at cavity B of C315 using a DVOM.

Is the voltage within the specified range?

4.8-5.2 V

Go to Step 5

Go to Step 6

Inspect the FPS ground circuit in cavity A for continuity to ground.

Is there continuity?

Go to Step 7

Go to Step 9

Turn the ignition OFF.
Disconnect CLR ECU connector C003.
Inspect the 5 volt reference circuit in cavity C of connector C315 using a DVOM for the following conditions:

•	A short to voltage,

•	A short to ground,

•	An open circuit.

Is a problem found?

Go to Step 13

Go to Step 11

Turn the ignition OFF.
Disconnect BLU ECU connector C001.
Inspect the FPS signal circuit for continuity to ground using a DVOM.

Is there continuity?

Go to Step 13

Go to Step 8

Inspect the FPS signal circuit for continuity between C001 and C315 using a DVOM.

Is there continuity?

Go to Step 10

Go to Step 13

Turn OFF the ignition.
Disconnect CLR ECU connector C003.
Inspect the FPS ground circuit for continuity between C003 and C315 using a DVOM.

Is there continuity?

Go to Step 10

Go to Step 13

Replace the fuel pressure sensor. Refer to Fuel Pressure Sensor Replacement .

Is the action complete?

Go to Step 14

Inspect the ECU connector for damaged wiring or pins.
Inspect connector C315 for damaged wiring or pins.

Is a problem found?

Go to Step 13

Go to Step 12

Replace the engine control unit. Refer to Engine Control Unit Replacement .

Is the action complete?

Go to Step 14

Repair the circuit as necessary. Refer to Repair Procedures in Electrical Diagnosis in the 1998 C/K Truck Service Manual.

Is the action compete?

Go to Step 14

Start the engine.
Allow the engine to idle for 15 seconds.
Turn OFF the ignition for 10 seconds.
Start the engine and allow it to reach operating temperature.
Turn OFF the ignition.
Verify that no other DTCs are displayed.

Are any other DTCs displayed that have not been diagnosed?

Go to the applicable DTC table

System OK