Key On Engine Running (KOER) Glow Plug Monitoring Self-Test
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2004 Ford RV Cutaway, 2004 Ford Pickup, 2004 Ford F550 Super Duty, 2004 Ford F450 Super Duty, and 2004 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.
Key On Engine Running (KOER) Glow Plug Monitoring Self-Test is a functional test of the glow plug system performed on demand with the engine running and the A/C off. Battery voltage must be maintained at 10-14 volts during this test. If necessary, press the accelerator pedal to increase voltage to the specified level. The PCM will activate the Glow Plug Control Module (GPCM) and monitor the glow plug circuits. A fault must be present at the time of testing for the test to detect a fault. DTCs will be sent to the PCM on the diagnostic line and then output to the scan tool.