Possible Causes (California & Federal)
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.
Insufficient glow plug "On" time will not allow enough heat to accumulate in combustion chamber resulting in a hard start condition. If glow plug system "On" time is insufficient, probable cause is a faulty wiring harness connector, bad ground connection or defective glow plug control module or relay. Look very carefully for poor connections, burnt or loose fitting pins that will cause high resistance.
- Glow Plug Control Module (GPCM) or glow plug relay.
- Power circuit to GPCM/relay (fusible links from starter relay).
- GPCM/relay to valve cover connector circuits.
- Valve cover gasket.
- Under valve cover (UVC) wiring harness.
- Glow plugs.