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sean, Ford Technician
Category: Ford
Satisfied Customers: 3105
Experience:  Ford Master Technician.
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none of the interior lights in my 2004 Mondeo GhiaX terbo diesel

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none of the interior lights in my 2004 Mondeo GhiaX terbo diesel work. I've checked the bulbs and the fuse in the main fuse box behind the glove compartment and all are OK. A frioend suggested disconnection of battery to ensure no static build up. This didn't work. I cant see the door switches so don't know what else to look at. Any ideas please

Hello, I hope I can offer you some assistance.

Do you have the chassis number of the car? So I can obtain the correct wiring details. Do the lights not work even if you turn them on manually?

Does the boot lamp work?

Let me know and I'll reply as soon as I'm able to.

Thank you.

Customer: replied 3 years ago.


Chasis number WF0WXXGBBW4L49852


The loghts do not work if turned on manually.


Sorry its an estate. There are 3 internal lights in total. Front and rear passenger units includes reading lights each side of internal lamp.


Plus There is a seperate roof light just in front of rear tailgate. None of the above work .



Hello again,

the interior lights are powered through the battery saver relay in the fuse box inside the car, this relay is triggered by the GEM. Check for 12 volts at pins 2 and 5 of the relay, these are supplied by fuse 7 in the fuse box under the bonnet. Pin 3 of the relay is earthed by the GEM to energize the relay, when the relay is energized pin 3 of the relay supplies 12 volts to fuse 99 in the interior fuse box, this is the interior light fuse.

If the relay isn't triggering then test it manually, you can supply pin 2 and earth pin 3 and see if the relay clicks. If the relay is operating manually but not in the car then check the GEM circuit. The battery saver relay is labelled as K 115 in the diagram below.


The pin locations are also shown and will be numbered on the relay if you remove it.

Start with these points, let me know if I can assist further and I'll reply as soon as I'm able to.

Best wishes,


sean and other Ford Specialists are ready to help you
Customer: replied 3 years ago.

Thanks Sean,

Don't know if you got my last email but could you tell me what GEM stands for.


I'll have a go at what you suggest over the next couple of days. I have an average understanding of non auto electrics so should be able to plod through. I'll let you know if i hit any brick walls.


Regards & thanks for the advice


Bob Haddad

Hello again,

the GEM is a Generic Electronic Module, this controls many functions on the car such as locking, wiper timing and the heated screens. It is located up behind the drivers side at the bottom of the "A" pillar and has 5 connectors to it.

Let me know if I can assist further.

Thank you.

Customer: replied 3 years ago.

Thanks Sean. I checked as you suggested and established the relay was faulty. Its now been replaced and the lights are working correctly. Thanks very much.



No problem, glad it's sorted.