Electrical system intermittent in MK3 Mondeo Ghia X

[Howard_silver]

I conducted a brief review but did not find anything that aligns with my specific circumstances, so I decided to submit in hopes of receiving insight or being directed to the appropriate resource.

I possess a 2004 Mondeo MK3 Ghia X equipped with a 3.0L V6 Duratec engine. The problem is that while driving, the interior electronics (as detailed below) and the headlights intermittently activate and deactivate, which is clearly problematic.


I initially believed the battery was failing; however, upon testing, it registered 13 volts after remaining idle without the engine running for a whole day.
The battery measures 14 volts with the engine running and 16 volts with the headlights activated, indicating that the alternator appears to be functioning properly.
Consistently initiates on the first attempt and engages and disengages properly.

I suspect the problem may stem from a loose connection; nevertheless, I am not a mechanic and lack certainty.

The brake lights function properly and have never malfunctioned, even when all other systems are deactivated; this same applies to the indicators, power steering, and the engine.

I am pleased to address enquiries and furnish further information if required.

Have any similar difficulties been observed? Is there anyone who can identify a probable cause?

Devices that have been activating and deactivating intermittently:
Dash cluster (all gauges simultaneously)
Power windows
Climate-controlled seats
Blower fans
Thermal displays
Radio or head unit
Headlight assembly (comprising sidelights, dipped beam, and main beam integrated into a single unit)

Thank you for any responses.

[CyberNinja]

Provide the findings for each phase of the test with greater precision than merely indicating 12v or 13v, etc.

[Howard_silver]

Understood, I will adhere to that and incorporate it into the original post if possible. Thank you for the clear directions! I am grateful for your notification.

[DSM10000]

Inspect the earthing negative wire for corrosion beneath the battery tray.

[Howard_silver]

I will examine that, thank you.

[CyberNinja]

There is no requirement to modify the original; simply present the outcomes below. Simply state the method employed for obtaining the readings.

Measure directly at the battery, from the lighter socket, or utilise an OBD instrument or dashboard diagnostics. They all exhibit modest variations but should yield a consistent overall voltage pattern.


16 volts may indicate an elevated level and suggest a deficient battery necessitating a high charging rate.

[Howard_silver]

Thank you for the valuable information.

Outcomes of alternator and battery examinations:


I recorded measurements directly from the battery; my multimeter can only display one decimal point. I trust this is adequate.

Battery voltage after overnight rest: 12.3V (fluctuating to 12.2V)

Battery voltage after 10 minutes of using headlights and warning lights: 12.1 volts

Battery voltage after 3 minutes of engine operation: 13.7V

Engine operational, lights, back window, and heated blowers: 13.1 volts

Please share your thoughts.

This afternoon, I will attempt to remove the battery and inspect the ground for stability, as suggested by the other respondent. Additionally, I possess an other battery that I may substitute for testing. Would it be prudent to replace it to determine if there is a variation in voltage?

[Howard_silver]

😍