AlwaysBuyMondeo Posted March 11 Share Posted March 11 Hi, I have a 2003 Mondeo Estate (my oldest Mondeo to date) and both of the main beam headlights have stopped working. I only realised when people started flashing me early one evening. All the other lights are OK, it's just both main beam lights. Here is what I have done to check and remedy with no success. Checked both 7.5A fuses and they are OK. I changed the Right headlight fuse to be sure. Checked both main beam bulbs and they are OK. I changed the Right headlight bulb to be sure. Changed the switch control box (the entire module with the main switch setting, height and brightness control) and this is not solved the problem. So, if it is not the bulbs, the fuses or the control box (sic) then what else could it be? To recap, all the other lights work OK including side lights, full-beam, indicators etc. NB: I get the lights on warning tone when the lights are ON and I open the door. NB: I noticed a few weeks ago the the fog-light on indicator was showing (small light to the bottom left of the control knob) when the lights were off. This was intermittent which is why I thought it might be the control box. If you fiddled / tapped it a bit the light would go off. NB: The other day (before I did any of the above) I got in the car and turned on the lights. I noticed the reflection on a wall, got out and the lights were on. I am 100% sure they were on. Drove home OK (10 mins) and they were not working next day. I need to get this fixed ASAP and need to try and avoid a garage visit where at all possible. All suggestions appreciated. m@ Quote Link to comment Share on other sites More sharing options...
TomsFocus Posted March 11 Share Posted March 11 Just to clarify - it's your dipped beams that aren't working. Main beam is also known as full beam or high beam. Perhaps you've been checking the wrong fuses? 1 Quote Link to comment Share on other sites More sharing options...
unofix Posted March 11 Share Posted March 11 mmmmmm............... thinking 🤔 I have virtually no information on the Mondeo 2003 model. On later models and in fact on all models now the Dipped beam (Low beam) headlights are controlled by what is now the Body Control Module (BCM) but on your car would be the General Electric Module (GEM). On nearly all models there are fuses for the Main beam (High beam) and very often a control relay, but this is not normally the case for the Dipped beam. Usually the lighting circuit for the Dipped beam is directly controlled by the GEM and there are no fuses or relays as the GEM provides the circuit protection. Mondeo's of the 2003 range are very prone to water ingress to the GEM module which is part of the fusebox in the passenger compartment. I would recommend disconnecting the car battery before investigating. Remove all connectors from the fuesbox / GEM and remove the entire assembly. Inspect all pins on the connectors for signs of greenish corrosion and water ingress. Check inside of the GEM for signs of corroded connections and track damage. 1 Quote Link to comment Share on other sites More sharing options...
AlwaysBuyMondeo Posted March 11 Author Share Posted March 11 Update: I did some more checking and fuse F88 behind the glove box is OK Quote Link to comment Share on other sites More sharing options...
AlwaysBuyMondeo Posted March 11 Author Share Posted March 11 To clarify further and make things clearer for all. 1. Indicator - Works OK 2. Sidelight - Works OK on all settings. 3. Main beam - Never works in any setting 4. Full beam - Works when 'flashed' or when on 'full-beam' using stalk and shows as blue light on dashboard. Flashes using stalk when lights off. I have been checking fuses: F88 (15A in glovebox) F16 (7.5A under bonnet) NB: bulbs not changed by me since owning 9 months) F18 (7.5A under bonnet) NB: bulbs not changed by me since owning 9 months) Quote Link to comment Share on other sites More sharing options...
AlwaysBuyMondeo Posted March 11 Author Share Posted March 11 55 minutes ago, unofix said: Mondeo's of the 2003 range are very prone to water ingress to the GEM module which is part of the fusebox in the passenger compartment. When I came back to my car and the lights were reflecting in the wall...it was raining. 😞 Quote Link to comment Share on other sites More sharing options...
AlwaysBuyMondeo Posted March 11 Author Share Posted March 11 57 minutes ago, unofix said: I would recommend disconnecting the car battery before investigating. Remove all connectors from the fuesbox / GEM and remove the entire assembly. Inspect all pins on the connectors for signs of greenish corrosion and water ingress. Check inside of the GEM for signs of corroded connections and track damage. Is this a single multi-port connector into the GEM/Fusebox, or are we talking about several? The fusebox is a pain to access and I assume is secured somehow so will need detaching before placing on a bench. Quote Link to comment Share on other sites More sharing options...
AlwaysBuyMondeo Posted March 11 Author Share Posted March 11 OK so focusing on the relay what are your thoughts on this? 1 Quote Link to comment Share on other sites More sharing options...
nicam49 Posted March 11 Share Posted March 11 They're controlled by relay 78...Fuses f86 and f85 feed each individual bulb, but relay 78 is common to both bulbs. The relay power is fed via F8, a 50 amp!! fuse. Here's a link to the fusebox info. https://www.fordwiki.co.uk/index.php/Fuse_%26_Relay_Information I was going to pm you with pics of the circuit from the Haynes, but seems it I can't do it and am not sure I can post it here on the public site due to copyright. If you want to, pm me your email address and I'll email you the pics directly. Quote Link to comment Share on other sites More sharing options...
unofix Posted March 11 Share Posted March 11 I would just like to clarify some headlight terminology so as the saying goes "we are all singing from the same hymn sheet" [A] The normal headlights used for driving at night are known as: Low Beam Dipped Beam [B] The more powerful brighter headlights (they cause the Blue warning light on the instrument cluster to illuminate) are known as: High Beam Full Beam Main Beam Having said that, are we talking about the normal headlights, Low Beam (Dipped Beam) which is light number 3 in your photo above ? 1 1 Quote Link to comment Share on other sites More sharing options...
AlwaysBuyMondeo Posted March 11 Author Share Posted March 11 42 minutes ago, nicam49 said: They're controlled by relay 78...Fuses f86 and f85 feed each individual bulb, but relay 78 is common to both bulbs. Thanks and have PMd you. Can I check is it 78? or 88? Quote Link to comment Share on other sites More sharing options...
unofix Posted March 11 Share Posted March 11 The video seems a very useful place to start. As the guy says remove the relay and provide a 12 volt supply to the terminal that feeds directly to the headlights and check that they both come on. Quote Link to comment Share on other sites More sharing options...
AlwaysBuyMondeo Posted March 11 Author Share Posted March 11 9 minutes ago, unofix said: I would just like to clarify some headlight terminology so as the saying goes "we are all singing from the same hymn sheet" [A] The normal headlights used for driving at night are known as: Low Beam Dipped Beam [B] The more powerful brighter headlights (they cause the Blue warning light on the instrument cluster to illuminate) are known as: High Beam Full Beam Main Beam Having said that, are we talking about the normal headlights, Low Beam (Dipped Beam) which is light number 3 in your photo above ? To clarify we are talking about A I could happily drive early evening with side-lights on, or blind the drivers of oncoming traffic but nothing in between. 1 Quote Link to comment Share on other sites More sharing options...
StephenFord Posted March 11 Share Posted March 11 4 hours ago, AlwaysBuyMondeo said: Checked both main beam bulbs and they are OK. I changed the Right headlight bulb to be sure. Changed the Right headlight - to what? Do you have access to a multi meter, if so, are you getting 12v pumped to the bulb connector? I know it's unlikely, but a couple of months back, I also had both dipped beam bulbs not working, went though lengthy diagnostics, and turned out that by a fluke coincidence, both bulbs had simply blown! 2 Quote Link to comment Share on other sites More sharing options...
AlwaysBuyMondeo Posted March 11 Author Share Posted March 11 10 minutes ago, StephenFord said: Changed the Right headlight - to what? Do you have access to a multi meter, if so, are you getting 12v pumped to the bulb connector? I know it's unlikely, but a couple of months back, I also had both dipped beam bulbs not working, went though lengthy diagnostics, and turned out that by a fluke coincidence, both bulbs had simply blown! I changed the bulb for a new like for like bulb. I replaced one fuse for new and the corresponding right bulb. This meant that the left fuse and bulb remain a constant whilst I try to find the fault. The story goes... A fortnight ago I realised both headlights had stopped working when on normal beam. After checking the fuses under the bonnet were OK I ordered a new set of bulbs online and was going to fit them when they arrived. Then, last week before the bulbs arrived I noticed both lights were working (see above comment) so realised it was unlikely to be bulbs or fuses. So, I ordered a new switch panel (see pic) and this didn't resolve the problem. Checked more fuses behind the glovebox and they were OK. Quote Link to comment Share on other sites More sharing options...
StephenFord Posted March 11 Share Posted March 11 3 minutes ago, AlwaysBuyMondeo said: Then, last week before the bulbs arrived I noticed both lights were working (see above comment) so realised it was unlikely to be bulbs or fuses. Not 'unlikely', but 100% rules them out. Once a bulb or fuse blows, it has no ability to resurrect itself... 1 Quote Link to comment Share on other sites More sharing options...
unofix Posted March 11 Share Posted March 11 3 hours ago, unofix said: Mondeo's of the 2003 range are very prone to water ingress to the GEM module which is part of the fusebox in the passenger compartment. I would recommend disconnecting the car battery before investigating. Remove all connectors from the fuesbox / GEM and remove the entire assembly. Inspect all pins on the connectors for signs of greenish corrosion and water ingress. Check inside of the GEM for signs of corroded connections and track damage. There are normally two but on some models three connectors for the GEM. Water ingress/corrosion would seem the most likely fault, especially since on one occasion you have seem the lights on when it was raining and you were not in the car. 1 Quote Link to comment Share on other sites More sharing options...
nicam49 Posted March 11 Share Posted March 11 1 hour ago, AlwaysBuyMondeo said: Thanks and have PMd you. Can I check is it 78? or 88? It's 78 according to Mr Haynes... I've emailed you the Circuits, btw Quote Link to comment Share on other sites More sharing options...
AlwaysBuyMondeo Posted March 15 Author Share Posted March 15 I can hear a click under the bonnet from the relay when I move the lights through to side-lights, low beam etc. There is also an audible click when flash the lights from under the dashboard. If I need to replace the relays. what are the values etc? Quote Link to comment Share on other sites More sharing options...
unofix Posted March 15 Share Posted March 15 By all means you can start randomly replacing relays, fuses, bulbs, switches etc. It will all take time and money and will almost certainly not fix the problem. You need to do an in-depth fault diagnosis with a multimeter and also physically remove and inspect the GEM unit. Yes you will hear relays clicking as you operate the lights, that's normally a good sign that they are working (but not always). I would recommend that you find a good Auto Electrician (not a mechanic) and get them to take a look and fix the fault. Quote Link to comment Share on other sites More sharing options...
nicam49 Posted March 15 Share Posted March 15 Try to locate which relay is clicking when you switch to dipped lights, and pull it out and look at the pins.... are they corroded etc. The clicking means the relay coil is OK, but doesn't test if the contacts are OK. Have you got a test meter? Did you find the 50 amp fuse (according to the Haynes circuit) and check it? If you suspect the relay and want to substitute it, then I suggest a visit to a breakers yard for a spare relay. Looking at my own mk3, the 50amp fuse is f7 in the battery fuse box (the markings are inside the lid) The relay is located in what Mr Haynes calls the "central junction box" which I assume is the one behind the glove box.*.... Happy hunting! *have just checked in my owners manual and Ford call it "Central Fuse Box" Here's a YouTube link, might help! Quote Link to comment Share on other sites More sharing options...
nicam49 Posted March 16 Share Posted March 16 Did you learn anything useful from the attached youtube vid? 1 Quote Link to comment Share on other sites More sharing options...
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