Hi all,

I recently bought a 2011 Mondeo MK4.5 (2.0 TDCI Titanium X)  a few months ago and had a few problems with it (now fixed) and figured I would create a post of how I repaired the issues I had in case others have similar problems in the future:

Headlights not working 'low beam bulb fault':

The main problem I had when receiving the car was that the headlights would only work intermittently, always displaying the same message on the dash 'Low beam bulb fault' 

This was a difficult problem to diagnose as the previous owner had attempted to repair by wiring both headlights together which either had never worked or had stopped working by the time I got the vehicle.

Nevertheless, the standard diagnostics were carried out:

• Replaced bulbs as per Ford Owners Manual: no change
• Checked fuses for continuity: All fuses operational
• OBD scan: Earth to ground fault on each headlight as well as BCM fault (this turned out to be the problem)
• Battery voltage checked (multiple electrical faults on car): Battery voltage satisfactory

At this point with the fault, the basic diagnostics were coming back fine other than the OBD diagnostic codes, without auto electrical experience it was difficult to progress further so this went to a local auto-electrician for more analysis. It quickly became very clear it was a serious fault with the BCM which was giving no output on the terminals assigned to the adaptive headlight system meaning BCM replacement was the only option to fix the issue. This then had to go to an official ford repair centre to have the BCM replaced and recoded to my keys, so wasn't something fixable DIY style. The root cause of the issues was reported as water ingress across pins on the actual BCM module where the main plugs connect from the car, main plugs were fine that connected onto the BCM.

Overall, if you are having issues with the lights similar to this, I would recommend checking the pins on the BCM for corrosion if you can rather than replacing headlights etc. though actually recoding will likely need to be completed by a main dealer (I've seen some services that can clone a BCM but can't comment on these). My repair was paid for by the car dealer I bought it from otherwise I may have considered this option.

Wipers only work on highest setting, cutting out frequently:

A secondary problem I had with the car was the wipers would only work consistently on the highest setting, frequently cutting out on the lower settings mid sweep leaving the wipers blocking my view. The only way to move the wipers was clicking back into the highest setting and slowly moving the stalk back down to the lower settings which would soon cut out again at random intervals. During the cut out even the automatic wiping when spraying washer fluid wouldn't work so quite annoying when driving.

I tried the following repairs in this order:

• Replaced the wipers: Made no change
• Replaced the wiper stalk: Made no change

After ruling out these solutions, I searched the forums and someone suggested to replace the R8 relay (intermittent wiper relay) with a similar problem so I tried this as a last ditch effort before going to an auto-electrician. This relay turned out to be faulty, and after replacing with the same relay model works perfectly. With functioning wipers, I can now see that the cut-out was happening when the auto rain sensor was lowering the frequency of the wipers as now when this condition is met they skip a wipe instead of cutting out completely as before.

Parking sensors not working:

When I got the car, the parking sensor button would flash twice and not function, this turned out to not need electrical equipment replacing as with the above issues but simply water ingress into the sensors which was fixed by spraying WD-40 into the sensors to displace the trapped water. Parking sensors now work perfectly.

 

If you have similar issues, I hope this report might help you in diagnosing the faults, I couldn't find many resources online to help especially with the lights/BCM fault and spent many hours going in circles! I just figured maybe I could save someone time if they find this post.

5 minutes ago, Jamesdearing101 said:

I bought an Mondeo MK4.5 a few months ago

I think you need to update your profile as it's showing Focus 2009

The fault with water ingress to the BCM on the Mk4 Mondeo is quite common. The water makes it's way through the inside of the wires from the screen wash pump. You need to check this on your car otherwise your new BCM will have a short life.

 

11 minutes ago, unofix said:

I think you need to update your profile as it's showing Focus 2009

The fault with water ingress to the BCM on the Mk4 Mondeo is quite common. The water makes it's way through the inside of the wires from the screen wash pump. You need to check this on your car otherwise your new BCM will have a short life.

 

Thanks for the response, I'll make sure to pull that pump out and check it as would rather not replace BCM again!

On 11/4/2023 at 5:12 PM, unofix said:

I think you need to update your profile as it's showing Focus 2009

The fault with water ingress to the BCM on the Mk4 Mondeo is quite common. The water makes it's way through the inside of the wires from the screen wash pump. You need to check this on your car otherwise your new BCM will have a short life.

 

Update: Thanks for sending me this! Took it to my local garage today and they found water in the cables off the power feed, fitted a new pump and got it nicely sealed for extra protection. Fair to say you've saved me some time and money!

You'd have thought that whoever resolved the BCM issue  would have been aware of this water ingress 'feature' and done something about it! 

6 hours ago, nicam49 said:

You'd have thought that whoever resolved the BCM issue  would have been aware of this water ingress 'feature' and done something about it! 

Was one of these 'car dealer repairs the minimum to get it running' situations, at the time repairer said it was likely because it had a new windscreen fitted (cracked one would have allowed water ingress) but clearly that was either a lie or just lack of knowledge. Either way, luckily got there in the end thanks to this forum!