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Test Description

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.
  2. 3:  This step determines if the condition is located on the coil side or the switch side of the circuit.
  3. 4:  This step verifies that the ECM is providing voltage to the fuel pump relay.
  4. 5:  This step tests for an open in the ground circuit to the fuel pump relay.
  5. 6:  This step determines if a voltage is constantly being applied to the fuel pump relay.
  6. 13:  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.
  7. 15:  Use the same amperage fuse in the jumper as is used to protect the fuel pump circuit.
  8. 17:  Inspect the ground connection for the fuel pump. Be certain all ground connections are clean and tight.
Fuel Pump Electrical Circuit Diagnosis

Step Action Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  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  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 9  Go to Step 4 
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 that is connected to a good ground.
  5. Command the fuel pump relay ON and OFF with a scan tool.
Does the test lamp turn ON and OFF?		 Go to Step 5  Go to Step 6 
5 
  1. Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay.
  2. Command the fuel pump relay ON and OFF with a scan tool.
Does the test lamp turn ON and OFF?		 Go to Step 19  Go to Step 22 
6  Does the test lamp remain illuminated with each command? Go to Step 7  Go to Step 8 
7 Test the control circuit of the fuel pump relay for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 27  Go to Step 26 
8 Test the control circuit of the fuel pump relay for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 27  Go to Step 20 
9 Turn ON the ignition, with the engine OFF.
Does the fuel pump operate continuously?		 Go to Step 10  Go to Step 11 
10
  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 21  Go to Step 25 
11 Is the fuel pump fuse open? Go to Step 12  Go to Step 14 
12
  1. Test the supply voltage circuit of the fuel pump for a grounded circuit between the fuel pump fuse and the fuel pump. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Replace the fuel pump fuse if necessary.
Did you find and correct the condition?		 Go to Step 27  Go to Step 13 
13 
  1. Install all disconnected electrical 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 24  Go to Intermittent Conditions 
14
  1. Turn OFF the ignition.
  2. Disconnect the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery voltage circuit of the fuel pump relay switch with a test lamp that is connected to a good ground.
Does the test lamp illuminate?		 Go to Step 15  Go to Step 23 
15  Connect a 20-amp fused jumper wire between the battery voltage circuit of the fuel pump relay switch and the supply voltage circuit of the fuel pump.
Does the fuel pump operate?		 Go to Step 19  Go to Step 16 
16 Test the supply voltage circuit of the fuel pump for an open or high resistance between the fuel pump relay and the fuel pump. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 27  Go to Step 17 
17 
IMPORTANT: Inspect the ground circuit for correct tightening, corrosion on the terminals, or damage to the wiring harness.
Test the ground circuit of the fuel pump for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 Go to Step 27  Go to Step 18 
18 Inspect for poor connections at the fuel pump. 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 27  Go to Step 24 
19 Inspect for poor connections 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 27  Go to Step 25 
20 Inspect for poor connections at the harness connector of the 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 27  Go to Step 26 
21 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 27  -
22 Repair the open in the ground circuit of the fuel pump relay. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 27  -
23 Repair the open in the battery voltage circuit of the fuel pump relay switch. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 27  -
24
IMPORTANT: Inspect for poor connections at the fuel pump, within the fuel tank, before replacing the fuel sender assembly.
  1. Replace the fuel sender assembly. Refer to Fuel Sender Assembly Replacement .
  2. Replace the fuel pump fuse if necessary.
Did you complete the replacement?		 Go to Step 27  -
25 Replace the fuel pump relay.
Did you complete the replacement?		 Go to Step 27  -
26 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 Go to Step 27  -
27 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 2 
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