Diagnostic Aids

WARNING: This page is about a different car, the 2004 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

Fuel Pump Electrical Circuit Diagnosis

Fuel Pump Relay Underhood Electrical Center Terminal Identification
Front of Vehicle
Left Side of Vehicle	Ground	Ignition 1	Right Side of Vehicle
Left Side of Vehicle	Fuel Pump Supply	Control	Right Side of Vehicle

The following conditions may have caused the fuel pump fuse to open:

The fuse was faulty.
There is an intermittent short in the supply voltage circuit of the fuel pump.
The fuel pump has an internal intermittent condition.

For an intermittent condition, refer to Intermittent Conditions .

Fuel Pump Electrical Circuit Diagnosis

Step	Action	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module (PCM) 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	Turn ON the ignition, with the engine OFF. Command the fuel pump relay ON and OFF with a scan tool. Repeat the commands as necessary. Does the fuel pump turn ON and OFF?	Go to Diagnostic Aids	Go to Step 3
3	Command the fuel pump relay ON and OFF with a scan tool. Do you hear the fuel pump relay click when you command the fuel pump relay ON and OFF?	Go to Step 9	Go to Step 4
4	Turn OFF the ignition. Remove the fuel pump relay. Turn ON the ignition, with the engine OFF. Probe the control circuit of the fuel pump relay with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems. 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	Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay. Command the fuel pump relay ON and OFF with a scan tool. Does the test lamp turn ON and OFF?	Go to Step 21	Go to Step 25
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 30	Go to Step 29
8	Test the control circuit of the fuel pump relay for a short to ground and for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 30	Go to Step 22
9	Turn ON the ignition, with the engine OFF. Does the fuel pump operate continuously?	Go to Step 10	Go to Step 11
10	Turn OFF the ignition. Remove the fuel pump relay. Turn ON the ignition, with the engine OFF. Does the fuel pump operate continuously?	Go to Step 24	Go to Step 28
11	Inspect the F/PMP fuse. Is the fuse open?	Go to Step 12	Go to Step 15
12	Remove the left rear wheel house panel. Refer to Wheelhouse Panel Replacement in Body Rear End. Disconnect the fuel pump harness in-line connector. Refer to Inline Harness Connector End Views in Wiring Systems. Test the supply voltage circuit of the fuel pump between the fuel pump relay and the fuel pump harness in-line connector for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Replace the F/PMP fuse if necessary. Did you find and correct the condition?	Go to Step 30	Go to Step 13
13	Remove the left fuel tank. Refer to Fuel Tank Replacement (Right) or Fuel Tank Replacement (Left) . Inspect the fuel sender harness on top of the fuel tank for the following conditions: Any damage to the harness A short to ground in the supply voltage circuit of the fuel pump-Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Replace the F/PMP fuse if necessary. Did you find and correct the condition?	Go to Step 30	Go to Step 14
14	Install all removed electrical components. Install a new F/PMP fuse. Command the fuel pump relay ON with a scan tool. Inspect the F/PMP fuse. Is the fuse open?	Go to Step 23	Go to Intermittent Conditions
15	Turn OFF the ignition. Remove the fuel pump relay. Turn ON the ignition, with the engine OFF. Probe the ignition 1 voltage circuit of the fuel pump relay, switch side, with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems. Does the test lamp illuminate?	Go to Step 16	Go to Step 26
16	Connect a 20-amp fused jumper wire between the ignition 1 voltage circuit of the fuel pump relay and the supply voltage circuit of the fuel pump. Does the fuel pump operate?	Go to Step 21	Go to Step 17
17	Remove the left rear wheelhouse panel. Refer to Wheelhouse Panel Replacement in Body Rear End. Disconnect the fuel pump harness in-line connector. Refer to Inline Harness Connector End Views in Wiring Systems. Test the supply voltage circuit of the fuel pump between the fuel pump relay and the fuel pump harness in-line connector for an open and for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 30	Go to Step 18
18	IMPORTANT: Inspect the ground circuit for proper torque, corrosion on the terminals, and damage to the wiring harness. Test the ground circuit of the fuel pump for an open and for high resistance between the fuel pump harness in-line connector and ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.Did you find and correct the condition?	Go to Step 30	Go to Step 19
19	Test for an intermittent and for a poor connection at the fuel pump harness in-line 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 30	Go to Step 20
20	Remove the left fuel tank. Refer to Fuel Tank Replacement (Right) or Fuel Tank Replacement (Left) . Inspect the fuel sender harness on top of the fuel tank for the following conditions: Any damage to the harness An open circuit-Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 30	Go to Step 23
21	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 30	Go to Step 28
22	Test for an intermittent and for a poor connection at the PCM. 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 30	Go to Step 29
23	Test for an intermittent and for a poor connection at the fuel pump connector within the fuel tank. 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 30	Go to Step 27
24	Repair the short to voltage in the supply voltage circuit of the fuel pump. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?	Go to Step 30	-
25	Repair the open or high resistance in the ground circuit of the fuel pump relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?	Go to Step 30	-
26	Repair the open in the ignition 1 voltage circuit of the fuel pump relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?	Go to Step 30	-
27	Replace the fuel pump. Refer to Fuel Sender Assembly Replacement (RH) or Fuel Sender Assembly Replacement (LH) . Replace the F/PMP fuse if necessary. Did you complete the replacement?	Go to Step 30	-
28	Replace the fuel pump relay. Did you complete the replacement?	Go to Step 30	-
29	Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement . Did you complete the replacement?	Go to Step 30	-
30	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2