1. Diagnosis: It's rarely just one glow plug.
* Don't jump to replacing glow plugs immediately. While a faulty glow plug is *possible*, the flashing light usually means a problem with the glow plug control module, wiring, or a relay. Replacing plugs without addressing the underlying issue is often a waste of money.
* Check the obvious: Ensure the battery is fully charged and has good connections. A weak battery can affect the glow plug system.
* Read the fault codes: Use an OBD-II code reader to retrieve diagnostic trouble codes (DTCs). This will pinpoint the specific problem area (e.g., a faulty glow plug relay, a short circuit in the wiring, or a malfunctioning glow plug control module). The code will be far more informative than the flashing light.
* Visual Inspection: Carefully examine the glow plug wiring harness for any signs of damage, such as fraying, broken wires, or corrosion. Pay close attention to the connections at both the plugs and the control module.
2. Potential Problems and Solutions (based on DTCs and visual inspection):
* Faulty Glow Plug(s): If the code indicates a specific glow plug, replacement is necessary. This usually requires specialized tools and some mechanical knowledge. It's often best done in pairs (or all at once for preventative maintenance).
* Glow Plug Relay: A malfunctioning relay prevents power from reaching the glow plugs. Replacing the relay is relatively inexpensive and straightforward. You can usually find the location in your car's manual or online forums.
* Glow Plug Control Module (PCM): This is the "brain" of the system. A faulty PCM is more expensive to replace and requires more technical knowledge or professional assistance. Again, the OBD-II code will be crucial here.
* Wiring Issues: Damaged or corroded wiring needs to be repaired or replaced. This might involve tracing the wiring harness to locate the fault. If you're not experienced with electrical work in vehicles, this is best left to a professional.
* Low Battery Voltage: A weak or failing battery can prevent the glow plug system from functioning properly. Have your battery tested to ensure it's holding a sufficient charge.
3. Repairing the Issue:
* DIY Repair (If you have mechanical experience and the correct tools): Replacing glow plugs, relays, and even some wiring is possible for those with experience. Refer to a repair manual specific to your Mondeo's year and model. Improper repair could damage other components.
* Professional Repair: If you are not comfortable performing repairs yourself, take your Mondeo to a qualified mechanic or Ford dealership. They have the diagnostic equipment and expertise to identify and fix the problem correctly.
Important Note: Continuing to drive with a flashing glow plug light can lead to further damage. It's best to address the issue promptly. The code reader is your best friend in this process. Without it, you're essentially guessing, which can be expensive and time-consuming.
