Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2003 Ford RV Cutaway, 2003 Ford Pickup, 2003 Ford F550 Super Duty, 2003 Ford F450 Super Duty, and 2003 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.
WARNING:
Red-striped wires carry 115 volts DC. Severe electrical shock may be received. DO NOT pierce engine electrical wires or damage to harness may occur.
Perform this test when directed by QUICK TEST. Glow plugs are energized during and after WAIT TO START light is on. When WAIT TO START light turns off, engine is ready to be started. This test is only intended to diagnose the following components and circuits:
- Glow Plug Light (GPL) Or WAIT TO START Light
- Instrument Cluster
- PCM
- Econoline & F650-750
Glow Plug WAIT TO START Lamp is used to indicate to operator when glow plugs have been on long enough to crank and start engine. It is controlled by PCM. WAIT TO START lamp ON time is a function of engine oil temperature, barometric pressure and battery voltage. ON time normally varies between 1-10 seconds. - Excursion & F250-550
Glow Plug Indicator Light (GPL) is used to indicate to operator when glow plugs have been on long enough to crank and start engine. GPL ON time is a function of engine oil temperature, barometric pressure and battery voltage. ON time normally varies between 1-10 seconds. Command to illuminate indicator is sent from PCM to instrument cluster through Standard Corporate Protocol (SCP) communications. PCM sends cluster an electronic SCP message for indicator function. Failure check is performed by instrument cluster and pass/fail information is sent back to PCM for setting of failed GPL, DTC P0381. DTC P0381 is an OBD-II code for California emission vehicles only and will illuminate CHECK ENGINE light. - Detection & Management
An open or shorted to ground glow plug relay or WAIT TO START lamp circuit can be detected during KOEO ON-DEMAND SELF-TEST. Glow plug and glow plug harness problems cannot be detected by PCM.
NOTE:
WAIT TO START light ON time is independent from glow plug relay ON time.