Chris, this may be a question for Taz or FBB but in the mean time have you done a continuity check between the switch and the connector behind the fog light? I use a spool of wire and alligator clips along with an Ohm meter to check. Turn off the power and do one wire at a time. If you are getting power to the switch from the fusebox logic would dictate that it must be a disconnect between the switch and the light connector. Worth doing a quick diagnostic and at least you can rule out a wire break / problem.

 

Not sure if that circuit is on a relay, or only a fuse. But ensure fuse #12 in the diagram below is OK. It also powers the registration plate lamps and the instrument panel lamps, so if all those are working, the foglamps should be also.

I was going to recommend that you take the fixture apart and clean any corrosion from the lamp & lampholder, but if you're not even getting 12v at the harness connector going to the fixture, then your problem is further upstream.

Relay "P" is described as being for "External Lights", which is just vague enough that it might include foglamps as well, so ensure all your "External Lights" are coming on.

Good luck, & please update the thread to let us know what you find.

 

Hi Bob,

Thanks for your nice answer! I have tried to follow the wire but this is near impossible at that point the complete wiretree is coming from the engineroom to the leg area / fusebox area - i have the original connection diagram but there is also a problem - at the diagram a connector is shown with 24pin's in a row but in reality its a connector with 3 x 8 pin's in row - so you dont know which pin is pin 1 - it's not marked anywhere so you have 4 possibilty's .... :-(
this connector is near the fusebox in the leg area. i thought i know my duchess very well, but this case is hard :-/

 

Hi John,

Thanks also for your reply

I had changed all fuses at the fusebox - no result. At the instrument panel the lamp is not going on.... All other lights on my duchess are working fine.
John, maybe you are right and relais P is for the foglights - i will check that today evening.

Best Regards

 

Chris, if your foglamps and instrument panel lamp are not coming on, check your rear license plate lamps as they're all on that same circuit. If the license plate lamps aren't coming on, AND you're sure the #12 fuse is OK, then there may be a bad connection or a bad trace on the motherboard leaving that fuse.

It does seem odd that you'd have +12 at your foglamp switch, as that point would be downstream of the #12 fuse. That would indicate the fuse panel wiring is OK.....

More probing recommended

 

I have checked the relay, it is working fine, the Standing lights are on - i also checked the rear licence plate lights, they are also working, so the Problem is on another Position. I checked again 12+ on the fuse - it's there when the lamps are on - seems to be a interuption between the fusebox and the wiretree going outside, what about the Connection between the fusebox and the instrumentpanel? on the electricityplan are several Connections - maybe the mistake is somewhere out there? it's :-( :-(

 

I am having some trouble following your post. Do you have power coming in and going out of the switch itself at the dash or is the problem between the fuseboard and the switch?

 

If it happened after a car wash, I would check all the earth connections first.

 

Or maybe just wait a week or two in case it dries out? I know that sounds a bit like wishful thinking, but it just might happen (and if it does it would save an awful lot of work). And you don't need fog-lights much at this time of year.

 

@PRS Guitarist:

I have Power on the Switch of the Dashboard on both sides. The Problem seems to be between the fusebox and the wire to the fog lights.

@wheels1: yes you are right, it was after a carwash...

I checked all earth Connections, removed and cleaned them and after that i build a direct one to the car Batterie just for a trial - no result :-(

@bluebottle: This was last September so i think it was long enough time to dries out, it seems to be another Problem but all this have to do something with my carwash in September.

@all: Thanks for your ideas, my troublesearching will go on and i will tell you, when i find something out.

 

Hey Chris,

do you have the wiring diagram complete?
Obviously complete for Ferrari standard, not like MB or BMW standard .....
I have the 550 paper wiring diagram at my father's home, I can scanning next week if you like.
Did you try to follow the wire from the fuse box on? If you do not find the pin can help you with a multimeter and a clamp for cables, or the tips.

Good luck

 

Hey Fabio,


I don't know exactly - i have a original repair handbook but i think ist not exactly at some Details ore some Information are not excist.
I have tried to follow the wire from the fuse to the wiretree going outside but i don't know at what Clip on the fuse box the wire of the foglight goes out because there are about five or six Clips which are going outside and to the Dashboard and so on. ??
A complete Diagramm would be very needfuly...
I have one idea left: I will remove all fuses except the one for the foglights, give 12V to the box and see on which Clip Position 12V are coming out - that should be the foglight


What to you think?


Many greetings Chris

 

update

Hi everybody,

Thanks again for your brainstorming - now i have found the problem - I was always searching in the engine room or controling the fusebox and the connection to the switch (there was 12+) BUT the cableconnection (one kable of it) behind the stereo-radio was disconnected.... so it had nothing to do with my carwashing bevor i recognised the problem with the lights.
Everything is working fine again!

Thanks again and many regards to all

Chris

 

Hi everybody,

Thanks again for your brainstorming - now i have found the problem - I was always searching in the engine room or controling the fusebox and the connection to the switch (there was 12+) BUT the cableconnection (one kable of it) behind the stereo-radio was disconnected.... so it had nothing to do with my carwashing bevor i recognised the problem with the lights.
Everything is working fine again!

Thanks again and many regards to all

Chris

Good news Chris,
My files did help you?

 

Hi Fabio,

I checked your files exactly but there are the same than i have - i have this two genuine repairbooks but somehing is strange: the sides in this book about the electrical things are not komplete - between L24 and L63 is nothing (the same like in your mail with the pdf's attached). have you the complete Chapter L ?

Many Greetings Chris