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Home >> Cadillac >> 2004 >> CTS Base, 3.2 N >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 20 (Engine Controls - 3.6L - Diagnosis (DTC P0351 - P1014)) >> Diagnosis >> DTC P0628 >> Test Description

Test Description

WARNING: This page is about a different variant/trim than selected.

The number below refers to the step number on the diagnostic table.

  1. 4:  This step verifies that the control module is providing voltage to the fuel pump relay.
DTC P0628 Fuel Pump Relay Control Circuit Low Voltage

Step Action Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Control Module (ECM) Connector End Views  or  Engine Controls Connector End Views 
1 Did you perform the Diagnostic System Check-Engine Controls? Go to Step 2  Go to Diagnostic System Check - Engine Controls
2
IMPORTANT: DTCs P1629, P1630, P1631and P2105 may cause this DTC to set. Refer to Diagnostic Trouble Code (DTC) List .
  1. Turn ON the ignition, with the engine OFF.
    2. IMPORTANT:
    • The Fuel Pump Relay Command parameter may not change from OFF to ON or ON to OFF when using the Fuel Pump output control.
    • Additional DTCs may set when using the Fuel Pump output control.
    • The fuel pump relay is located under the rear seat.
  2. Command the fuel pump ON and OFF with a scan tool.
Does the fuel pump relay turn ON and OFF with each command?		 Go to Step 3  Go to Step 4 
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition 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/Failure Records.
Did the DTC fail this ignition?		 Go to Step 4  Go to Diagnostic Aids
4 
  1. Turn OFF the ignition.
  2. Remove the rear seat cushion. Refer to Seat Cushion Replacement - Rear in Seats.
  3. Disconnect the fuel pump relay.
  4. Turn ON the ignition, with the engine OFF.
  5. Probe the control circuit of the fuel pump relay with a test lamp connected to a good ground.
    6. IMPORTANT:
    • The Fuel Pump Relay Command parameter may not change from OFF to ON or ON to OFF when using the Fuel Pump output control.
    • Additional DTCs may set when using the Fuel Pump output control.
  6. Command the fuel pump ON and OFF with a scan tool.
Does the test lamp turn ON and OFF?		 Go to Step 6  Go to Step 5 
5 Test the control circuit of the fuel pump relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 8  Go to Step 7 
6 Replace the fuel pump relay.
Did you complete the replacement?		 Go to Step 8  -
7 Replace the engine control module (ECM). Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 Go to Step 8  -
8
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition 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/Failure Records.
Did the DTC fail this ignition?		 Go to Step 2  Go to Step 9 
9 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
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