LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 2006 >> STS Base, 3.6 7, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 3.6L - DTC P0342 To P0690 >> DTC P0628 >> Test Description
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Test Description

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 Connector End Views  or  Engine Controls Connector End Views 
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle
2
IMPORTANT:
  1. Turn ON the ignition, with the engine OFF.
  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. Disconnect the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the control circuit of the fuel pump relay with a test lamp connected to a good ground.
  5. 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 .
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 Control Module References for replacement, setup, and programming.
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 - Vehicle System OK
scientia non olet · About LEMON Manuals