Circuit/System Testing (w/o LY6)
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
- With the ignition OFF, disconnect the harness connector at the FPCM.
- With the ignition ON, engine OFF, probe the control circuit of the fuel pump control module terminal 13 with a test lamp that is connected to a good ground. Command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF with each command.
- If the test lamp does not turn ON and OFF, test for an open, high resistance, or a short to ground in the fuel pump relay control circuit, an intermittent or a poor connection at the engine control module (ECM). If the circuit tests normal, replace the control module.
- If the test lamp remains illuminated with each command, test for a short to voltage in the control circuit of the fuel pump relay or an intermittent or a poor connection at the ECM. If the circuit tests normal, replace the control module.
- If all circuits test normal, replace the FPCM.