Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5535841
Diagnostic Instructions
Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic
System Check - Vehicle
Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis
An overview of each diagnostic category can be found here: Diagnostic Procedure
Instructions
DTC Descriptor
DTC P0186
Fuel Temperature Sensor 2 Performance
DTC P0191
Fuel Rail Pressure Sensor Performance
DTC P0192
Fuel Rail Pressure Sensor Circuit Low
DTC P0193
Fuel Rail Pressure Sensor Circuit High
DTC P127C
Fuel Rail Pressure Sensor 2 Circuit Low
DTC P127D
Fuel Rail Pressure Sensor 2 Circuit High
Diagnostic Fault Information
| Circuit |
Short to Ground |
Open/High Resistance |
Short to Voltage |
Signal Performanc |
| 5 V Reference |
P0193, P06A3, P127D |
P0193, P127D |
P0193, P06A3, P127D |
— |
| Signal — Fuel Rail Pressure Sensor |
P0192 |
P0193 |
P0193 |
P0191 |
| Signal — Fuel Rail Pressure Sensor 2 / Fuel Rail Temperature Sensor |
P127C |
P127D |
P127D |
P0186, P0191 |
| Low Reference |
— |
P0193, P127D |
P0193, P127D |
P0186, P0191 |
Typical Scan Tool Data
Fuel Rail Pressure Sensor
|
Circuit |
Short to Ground |
Open |
Short to Voltage |
|
|
Operating Conditions: Engine = Running Parameter Normal Range: 0.2 to 4.8 V |
|
|
|
|
|
5 V Reference |
5 V |
5 V |
5 V |
|
|
© 2023 Gener |
al Motors. All right |
s reserved. |
|
|
| Signal Circuit |
0 V Short to Ground |
5 V Open |
5 V Short to Voltage |
| Low Reference |
— |
5 V |
— |
Fuel Rail Pressure Sensor 2
| Circuit |
Short to Ground |
Open |
Short to Voltage |
| Operating Conditions: Engine = Running Parameter Normal Range: 0.2 to 4.8 V |
|
|
|
| 5 V Reference |
0 V |
4 V |
4 V |
| Signal |
0 V |
0 V |
0 V |
| Low Reference |
— |
0 V |
— |
Fuel Rail Temperature Sensor
| Circuit |
Short to Ground |
Open |
Short to Voltage |
| Operating Conditions: Engine = Running Parameter Normal Range: −39 to 214°C (−38 to 417°F) |
|
|
|
| Signal |
215°C (417°F) |
−40°C (−40°F) |
−40°C (−40°F) |
| Low Reference |
— |
−40°C (−40°F) |
— |
Circuit/System Description
For an overview of the component/system, refer to: Fuel System Description
| Circuit |
Description |
| 5 V Reference |
Regulated voltage supplied by the control module. |
| Signal |
The control module input circuit has an internal resistance connected to 5 V. |
| Low Reference |
Grounded through the control module. |
|
Component |
Description |
|
|
B47B Fuel Rail Pressure Sensor |
The sensor measures fuel rail pressure and fuel rail |
|
| Component |
Description |
|
temperature. |
| K20 Engine Control Module |
The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly. |
Conditions for Running the DTC
P0186
DTC P0181, P0182, P0183, P0184, P16D7, P16D8, P16D9 = Not set
Engine Coolant Temperature Sensor = Warmer than −40°C (−40°F)
Engine Off Time = Greater than 8 h
Ignition = On
Ignition and Start Signal = Greater than 5 V
Frequency the DTC runs = Once — Per cold start-up — After the running conditions are met
P0191
DTC P0116-P0119, P0128, P0192, P0193, P111E, P127C, P127D, P262B = Not set
Engine Coolant Temperature Sensor = Warmer than −40°C (−40°F)
Engine Off Time = Greater than 8 min
Ignition and Start Signal = Greater than 11 V
Ignition On or Engine Cranking — For greater than 15 s
Frequency the DTC runs = Continuously — After the running conditions are met
P0192, P0193, P127C, P127D
Ignition and Start Signal = Greater than 8.4 V
Ignition and Start Switch Signal = On
Frequency the DTC runs = Continuously — After the running conditions are met
Conditions for Setting the DTC
P0186
Fuel Rail Temperature Sensor & Fuel Temperature Sensor = Not within 15°C (27°F) of each other
@ Cold Start-Up — For less than 1 s
P0191
Fuel Rail Pressure Sensor & Fuel Rail Pressure Sensor 2 = Not within 25 MPa (3626 PSI) of each
other — For greater than 1 s
P0192
Fuel Rail Pressure Sensor = Less than 0.2 V — For greater than 1 s
P0193
Fuel Rail Pressure Sensor = Greater than 4.8 V — For greater than 1 s
P127C
Fuel Rail Pressure Sensor 2 = Less than 0.2 V — For greater than 1 s
P127D
Fuel Rail Pressure Sensor 2 = Greater than 4.8 V — For greater than 1 s
Actions Taken When the DTC Sets
DTCs listed in the DTC Descriptor category = Type A DTC — Exceptions listed below
DTC P0186 = Type C DTC
Conditions for Clearing the DTC
DTCs listed in the DTC Descriptor category = Type A DTC — Exceptions listed below
DTC P0186 = Type C DTC
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Master Electrical Component List
Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References
Circuit/System Verification
- Ignition » On / Vehicle » In Service Mode
- Verify DTC P0186 is not set and no other DTCs are set.
⇒ If only DTC P0186 is set
2.1. Ignition/Vehicle » Off — For greater than 8 h
2.2. Ignition » On / Vehicle » In Service Mode
2.3. Verify the following parameters are within 15°C (27°F) of each other:
Ambient Air Temperature
Fuel Rail Temperature Sensor
Fuel Temperature Sensor
⇒ If not within 15°C (27°F) of each other
{ Ambient Air Temperature } Refer to: DTC P0071-P0074
{ Fuel Rail Temperature Sensor } Refer to: Circuit/System Testing
{ Fuel Temperature Sensor } Refer to: DTC P0181-P0184
⇓ If within 15°C (27°F) of each other
2.4. Verify the scan tool parameter: Fuel Rail Pressure Sensor / Fuel Rail Pressure Sensor 2 &
Fuel Rail Temperature Sensor = The parameter value should not change
Perform the action while monitoring the parameter:
Wiggle the harness and connector: B47B Fuel Rail Pressure Sensor
Wiggle the harness and connector: K20 Engine Control Module
⇒ If the parameter value changes » Repair as necessary » Wiring / Terminal(s) / Electrical
Connector(s)
⇓ If the parameter value does not change
2.5. 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
data.
Verify the DTC does not set.
⇒ If the DTC sets » Refer to: Circuit/System Testing
⇓ If the DTC is not set
2.6. All OK.
⇓ If other DTCs are set
2.1. Ignition » On / Vehicle » In Service Mode
2.2. Verify the scan tool parameter: Fuel Rail Pressure Sensor & Fuel Rail Pressure Sensor 2 =
0.2 to 4.8 V
⇒ If not between 0.2 and 4.8 V
Refer to: Circuit/System Testing
⇓ If between 0.2 and 4.8 V
2.3. Engine » Running
2.4. Perform the scan tool control function: Fuel Rail Pressure » Increase & Decrease
Verify the scan tool parameter: Fuel Rail Pressure Sensor & Fuel Rail Pressure Sensor 2 =
The value should change with each command.
⇒ If the value does not change
Refer to: Circuit/System Testing
⇓ If the value changes
2.5. Verify the following parameters are within 25 MPa (3625.9 PSI) of each other:
Fuel Rail Pressure Sensor
Fuel Rail Pressure Sensor 2
⇒ If not within 25 MPa (3625.9 PSI) of each other » Refer to: Circuit/System Testing
⇓ If within 25 MPa (3625.9 PSI) of each other
2.6. Verify the scan tool parameter: Fuel Rail Pressure Sensor / Fuel Rail Pressure Sensor 2 &
Fuel Rail Temperature Sensor = The parameter value should not change
Perform the action while monitoring the parameter:
Wiggle the harness and connector: B47B Fuel Rail Pressure Sensor
Wiggle the harness and connector: K20 Engine Control Module
⇒ If the parameter value changes » Repair as necessary » Wiring / Terminal(s) / Electrical
Connector(s)
⇓ If the parameter value does not change
2.7. 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
data.
Verify the DTC does not set.
⇒ If the DTC sets » Refer to: Circuit/System Testing
⇓ If the DTC is not set
2.8. All OK.
⇓ If no DTC is set
- All OK.
Circuit/System Testing
- Ignition/Vehicle & All vehicle systems » Off
- Disconnect the electrical connector: B47B Fuel Rail Pressure Sensor
- Test for less than 10 Ω between the test points: Low Reference circuit terminal 3 & Ground
⇒ If 10 Ω or greater
3.1. Disconnect the appropriate electrical connector: K20 Engine Control Module
3.2. Test for less than 2 Ω between the test points: Low Reference circuit terminal 3 @
Component harness & The other end of the circuit @ Control module harness
⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit.
⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module
⇓ If less than 10 Ω
- Ignition » On / Vehicle » In Service Mode
- Test for 4.8 to 5.2 V between the test points: 5 V Reference circuit terminal 1 & Low Reference
circuit terminal 3
⇒ If less than 4.8 V
5.1. Ignition/Vehicle » Off
5.2. Disconnect the appropriate electrical connector: K20 Engine Control Module
5.3. Test for infinite resistance between the test points: 5 V Reference circuit terminal 1 @
Component harness & Ground
⇒ If less than infinite resistance » Repair the short to ground on the circuit.
⇓ If infinite resistance
5.4. Test for less than 2 Ω between the test points: 5 V Reference circuit terminal 1 @
Component harness & The other end of the circuit @ Control module harness
⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit.
⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module
⇒ If greater than 5.2 V
5.1. Ignition/Vehicle » Off
5.2. Disconnect the appropriate electrical connector: K20 Engine Control Module
5.3. Ignition » On / Vehicle » In Service Mode
5.4. Test for less than 1 V between the test points: 5 V Reference circuit terminal 1 @
Component harness & Ground
⇒ If 1 V or greater » Repair the short to voltage on the circuit.
⇒ If less than 1 V » Replace the component: K20 Engine Control Module
⇓ If between 4.8 and 5.2 V
- Verify the scan tool parameter:
Fuel Rail Pressure Sensor = Greater than 4.8 V
Fuel Rail Pressure Sensor 2 = Less than 0.2 V
⇒ If not the specified values
6.1. Ignition/Vehicle » Off
6.2. Disconnect the appropriate electrical connector: K20 Engine Control Module
6.3. Test for infinite resistance between the test points:
Signal circuit terminal 4 @ Component harness & Ground
Signal circuit terminal 2 @ Component harness & Ground
⇒ If less than infinite resistance » Repair the short to ground on the circuit.
⇒ If infinite resistance » Replace the component: K20 Engine Control Module
⇓ If the specified values
- Connect a 3 A fused jumper wire between the test points:
Signal circuit terminal 4 & Ground
Signal circuit terminal 2 & Ground
- Verify the scan tool parameter: Fuel Rail Pressure Sensor & Fuel Rail Pressure Sensor 2 = Less
than 0.2 V
⇒ If 0.2 V or greater
8.1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
8.2. Disconnect the appropriate electrical connector: K20 Engine Control Module
8.3. Ignition » On / Vehicle » In Service Mode
8.4. Test for less than 1 V between the test points:
Signal circuit terminal 4 @ Component harness & Ground
Signal circuit terminal 2 @ Component harness & Ground
⇒ If 1 V or greater » Repair the short to voltage on the circuit.
⇓ If less than 1 V
8.5. Ignition/Vehicle » Off
8.6. Test for less than 2 Ω between the test points:
Signal circuit terminal 4 @ Component harness & The other end of the circuit @
Control module harness
Signal circuit terminal 2 @ Component harness & The other end of the circuit @
Control module harness
⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit.
⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module
⇓ If less than 0.2 V
- Test or replace the component: B47B Fuel Rail Pressure Sensor
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair
Verification
High Pressure Diesel Fuel Sensor Replacement — B47B Fuel Rail Pressure Sensor
For control module replacement, programming, and setup refer to: Control Module
References