U1802
DTC U1802
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC U1802
-
Lost Communication With Fuel Pump Driver Control Module (FPCM) Relay
Diagnostic Fault Information
Circuit/System Description
The serial data circuits are controller area network (CAN) high and/or low speed serial data buses used to communicate information between the control modules.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
* The DTC sets when performing a diagnostic that monitors the state of health of the FPCM relay serial data circuits. The fuel pump control module device failure occurs when the periodic supervisory signal is lost, and no communication with the FPCM over the serial data communication (CAN) circuits.
* The above condition is present for greater than 30 milliseconds.
Action Taken When the DTC Sets
DTCs U1802 are Type A DTCs.
Conditions for Clearing the DTC
* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear after 100 malfunction-free ignition cycles have occurred.
Diagnostic Aids
Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.
Reference Information
Schematic Reference
Engine Controls Schematics (LS3) [1][2]Electrical DiagramsEngine Controls Schematics (LS7) [1][2]Electrical DiagramsEngine Controls Schematics (LS9) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 5 Bow Lowered Switch (CM7)
Description and Operation
Fuel System Description (LS3 or LS7) Description and OperationFuel System Description (LS9) Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Fuel Pump Flow Control Module Scan Tool Information Testing and Inspection for scan tool information
Circuit/System Verification
Ignition ON, command the fuel pump ON and OFF using the scan tool FPCM output control. The fuel pump should turn ON and OFF.
Circuit/System Testing
1. Ignition OFF, disconnect the X2 harness connector at the FPCM relay, and the harness connector at the FPCM.
2. Ignition ON, test for less than 1 V between the following terminals listed below and ground.
* FPCM serial data circuit terminal 40
* FPCM serial data circuit terminal 39
• If greater than the specified value, test the appropriate serial data circuit for a short to voltage. If the circuit tests normal, replace the FPCM relay.
3. Ignition OFF, Test for infinite resistance between the following terminals listed below and ground.
* FPCM serial data circuit terminal 40
* FPCM serial data circuit terminal 39
• If not the specified value, test the appropriate serial data circuit for a short to ground. If the circuit tests normal, replace the FPCM relay.
4. Test for less than 2 ohms between the appropriate serial data circuit terminals listed below.
* Serial data circuit terminal 40 at the FPCM harness connector and terminal 3 at the FPCM relay harness connector.
* Serial data circuit terminal 39 at the FPCM harness connector and terminal 4 at the FPCM relay harness connector.
• If greater than the specified value, test the appropriate serial date circuit for an open/high resistance. If the circuit tests normal, replace the FPCM relay.
5. Test for infinite resistance between the FPCM serial data circuit terminal 40, and the FPCM serial data circuit terminal 39.
• If not the specified value, repair the serial data circuits for a short together.
6. If all circuits test normal, replace the FPCM.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Fuel Pump Flow Control Module Replacement Fuel Pump Flow Control Module Replacement
* Fuel Pump Flow Control Module Relay Replacement Fuel Pump Flow Control Module Relay Replacement
* Control Module References Control Module References for FPCM replacement, setup, and programming