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Home >> Cadillac >> 2004 >> CTS Base, 3.6 7 >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Controls - 2.6L & 3.2L - Troubleshooting & Diagnosis) >> Troubleshooting >> Fuel Pump Electrical Circuit Diagnosis >> Test Description

Test Description

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

The numbers below refer to the step numbers on the diagnostic table:

  1. 2:  Command both the ON and OFF states. Repeat the commands as necessary. This can be determined by listening for an audible hiss from the fuel pump when the fuel pump relay is commanded ON or a vibration in the fuel feed line.
  2. 3:  This step determines if the condition is located on the coil side or the switch side of the relay.
  3. 5:  This step determines if the fuel pump relay is stuck closed.
  4. 7:  This step tests for a grounded voltage supply circuit. The fuel pump fuse supplies power to fuel pump. Disconnecting the fuel pump in-line harness connector isolates the fuel pump voltage supply circuit.
  5. 9:  This step verifies that the ECM is providing voltage to the fuel pump relay.
  6. 10:  This step verifies that the fuel pump fuse is providing voltage to the fuel pump relay.
  7. 11:  This step tests for an open circuit or a short to ground causing an open MaxiFuse.
  8. 12:  This step bypasses the fuel pump relay in order to activate the fuel pump.
  9. 13:  This step tests for an open in the fuel pump feed circuit between the in-line connector and the fuel pump relay.
  10. 16:  This step tests for an open or high resistance in the fuel pump ground circuit.
  11. 18:  This step determines if the condition with the circuit is intermittent. If the fuse does not open, inspect the supply voltage circuit between the fuse and the fuel pump for an intermittent condition.
Fuel Pump Electrical Circuit Diagnosis

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 
  1. Turn ON the ignition, with the engine OFF.
  2. Command the fuel pump relay ON and OFF with a scan tool.
Does the fuel pump turn ON and OFF?		 Go to Intermittent Conditions  Go to Step 3 
3 
  1. Remove the rear seat. Refer to Seat Cushion Replacement - Rear in Seats.
    2. IMPORTANT: An audible click should be heard.
  2. Command the fuel pump relay ON and OFF with a scan tool.
Do you hear a click when you command the fuel pump relay ON and OFF?		 Go to Step 4  Go to Step 9 
4 Turn ON the ignition, with the engine OFF.
Does the fuel pump operate continuously?		 Go to Step 5  Go to Step 6 
5 
  1. Turn OFF the ignition.
  2. Disconnect the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
Does the fuel pump operate continuously?		 Go to Step 20  Go to Step 24 
6 Is the fuel pump fuse open? Go to Step 7  Go to Step 10 
7 
  1. Disconnect the fuel pump harness in-line connector located near the fuel tank. Refer to Power and Grounding Component Views in Wiring Systems.
  2. Test the supply voltage circuit of the fuel pump for a grounded circuit. Refer to Wiring Repairs and Connector Repairs in Wiring Systems.
  3. Replace the fuel pump fuse if necessary.
Did you find and correct the condition?		 Go to Step 26  Go to Step 8 
8
  1. Lower the fuel tank if necessary. Refer to Fuel Tank Replacement .
  2. Test or inspect the fuel tank electrical harness for the following conditions:
  3. Replace the fuel pump fuse if necessary.
Did you find and correct the condition?		 Go to Step 26  Go to Step 17 
9 
  1. Turn OFF the ignition.
  2. Disconnect the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the fuel pump relay control circuit with a test lamp connected to a ground.
  5. Command the fuel pump ON and OFF with a scan tool.
Did the test lamp illuminate?		 Go to Step 18  Go to Step 19 
10 
  1. Turn OFF the ignition.
  2. Disconnect the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive voltage circuit of the fuel pump relay with a test lamp connected to a good ground.
Does the test lamp illuminate?		 Go to Step 12  Go to Step 11 
11 
  1. Turn OFF the ignition.
  2. Disconnect the fuel pump fuse.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive side of the fuel pump fuse, with a test lamp connected to a good ground.
Does the test lamp illuminate?		 Go to Step 21  Go to Step 22 
12  Connect a 15-amp fused jumper wire between the battery positive voltage circuit and the fuel pump supply circuit in the fuel pump relay cavity.
Does the fuel pump operate?		 Go to Step 18  Go to Step 13 
13 
  1. Disconnect the fuel pump harness in-line connector located near the fuel tank. Refer to Power and Grounding Component Views in Wiring Systems.
  2. Test the supply voltage circuit of the fuel pump for an open or for high resistance between the fuel pump relay and the in-line connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 26  Go to Step 14 
14
IMPORTANT: Inspect the fuel pump ground circuit for being tight, corrosion on the terminals, or damage to the wiring harness.
Test the ground circuit of the fuel pump for an open or for high resistance between the body pass through connector and the ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 Go to Step 26  Go to Step 15 
15 Test for an intermittent and for a poor connection at the fuel pump in-line connector to the body pass through connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 26  Go to Step 16 
16 
  1. Lower the fuel tank. Refer to Fuel Tank Replacement .
  2. Test or inspect the fuel tank electrical harness for the following conditions:
Did you find and correct the condition?		 Go to Step 26  Go to Step 23 
17
  1. Connect all disconnected components.
  2. Install a new fuel pump fuse.
  3. Command the fuel pump ON with a scan tool.
Is the fuel pump fuse open?		 Go to Step 23  Go to Intermittent Conditions 
18  Test for an intermittent and for a poor connection at the fuel pump relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 26  Go to Step 24 
19 Test for an intermittent and for a poor connection at the harness of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 26  Go to Step 25 
20 Repair the supply voltage circuit of the fuel pump for a short to voltage. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 26  -
21 Repair the battery positive voltage circuit of the fuel pump relay for an open. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 26  -
22 Repair the battery positive voltage circuit of the fuel pump fuse for an open or a short to ground. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 26  -
23
IMPORTANT: Inspect for poor connections at the fuel pump, within the fuel tank, before replacing the fuel pump.
  1. Replace the right fuel tank module. Refer to Fuel Tank Module Replacement - Primary .
  2. Replace the fuel pump fuse if necessary.
Did you complete the replacement?		 Go to Step 26  -
24 Replace the fuel pump relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems.
Did you complete the replacement?		 Go to Step 26  -
25 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 Go to Step 26  -
26 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 2 
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