Mondeo 2009 no rear lights including tailgate lights

[benjo247]

Hi all - I hope someone can help with my rear lights issue. 

For a few weeks now i've been noticing issues with the rear lights. At times both sides are fine, then only one side is working and sometimes neither OS or NS lights are working. The brake lights, hazards and reverse lights are working fine.

After doing a bit of research, I changed the bulbs and checked the bcm for corrosion and nothing was noticeable. I also checked the connector above the rear which arches and no corrosion or signs of dampness.  The car has spent over 5 hrs in 2 different garages and they both can't diagnose the issue but they think it's ECU related.

Which ECU do the rear lights connect to and where is it located.

At the moment having exhausted most suggestions from forums and youtube, I'm considering taking it to a specialist. Could someone please recommend a ford specialist - I'm based in Manchester. I have looked through the recommended list (painful exercise due to lack of ability to search) but i didn't find any in Manchester.

Just to add, all other lights are working fine. No other issues with the car and no warning lights on the dashboard.

Many thanks

[dezwez]

have you disconnected the battery i did this on my sons and it all worked when i reconnected them after 30 mins

[benjo247]

2 minutes ago, dezwez said:

have you disconnected the battery i did this on my sons and it all worked when i reconnected them after 30 mins

Yes. I disconnected the battery for an hour with the hope this would clear any errors but no change.

[unofix]

Both of the rear tail lights are controlled directly from the Body Control Module (BCM), there are no fuses.

The left and right tail lights each have their own circuit to the BCM so that they can be operated individually when using the parking light system controlled by the indicator stalk.

Partial failure of the BCM due to water ingress is quite common on the Mondeo. You need to disconnect the battery negative lead before beginning work. Fully remove all connectors from the BCM and remove it from the vehicle. check both sides of the BCM and all connectors very carefully. Look for signs of water and/or greenish corrosion.

[benjo247]

1 hour ago, unofix said:

Both of the rear tail lights are controlled directly from the Body Control Module (BCM), there are no fuses.

The left and right tail lights each have their own circuit to the BCM so that they can be operated individually when using the parking light system controlled by the indicator stalk.

Partial failure of the BCM due to water ingress is quite common on the Mondeo. You need to disconnect the battery negative lead before beginning work. Fully remove all connectors from the BCM and remove it from the vehicle. check both sides of the BCM and all connectors very carefully. Look for signs of water and/or greenish corrosion.

Thanks for your response. I have disconnected the battery and removed the bcm and there are no signs of water or corrosion. Also checked the connectors and they look pristine... let me attach some images. I can't see any water damage sign.

[unofix]

1 hour ago, benjo247 said:

Also checked the connectors and they look pristine

Yes I agree, it all looks in good condition.

The BCM monitors the current that each of the tail lights takes, and in the event of a fault it will turn off the circuit. With each new ignition cycle the BCM will recheck the circuit to see if the fault has cleared, and if so it will turn it back on.

It's a bit of a long shot, but I'd suspect damage to the wiring harness but unfortunately I have no circuit diagrams for your model. It is looking like you are going to need a good auto-electrician to take a look at it.

[benjo247]

19 hours ago, unofix said:

Yes I agree, it all looks in good condition.

The BCM monitors the current that each of the tail lights takes, and in the event of a fault it will turn off the circuit. With each new ignition cycle the BCM will recheck the circuit to see if the fault has cleared, and if so it will turn it back on.

It's a bit of a long shot, but I'd suspect damage to the wiring harness but unfortunately I have no circuit diagrams for your model. It is looking like you are going to need a good auto-electrician to take a look at it.

Thanks. Can somebody please recommend an auto-electrician in Manchester/ northwest.