Can anyone answer this fuse question?

[Swanny78]

Hi all, I have posted a question on FB and a few other sites but no one can seem to answer this.
I installed some LED bulbs in my 2017 GT, actually built in 2018 but 17 shape. Passenger one went in fine driver I must have shorted as it no longer works. Tried known good bulbs but nada. I see other 2017 owners say its a fuse and called on demand lighting in fuse location 1. Issue is I don't have a fuse in location one. I believe this is the case of all 2018 Mustangs. Where the hell is the fuse then. My Manuel says location 1 but I assume its a 2017 manual, even tho my car was manufactured in 2018. Any help greatly appriciated. Odd passenger map light works but not driver...must be on different circuit ? Its a right hand drive UK car. So passenger on left side etc. .

Please please help its driving me mad.

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[ugstang17]

You do understand that LED's are polarity sensitive correct? They are a diode that glows. For a diode to forward bias (turn on) A positive potential must be felt on the anode and a negative on the cathode. This forward biases the diode allowing current flow. The opposite reverse biases the diode and opposes current flow. Make sure you have the 12vdc positive on the anode, but first verify that you have 12vdc at the source with a multimeter. Then check the other wire to ground to ensure you don't have an open circuit. This can be verified by measuring resistance of the wire to ground. Reading 2ohms or less to ground will indicate a good connection. Good luck.

 

[Swanny78]

Hi ugstang17, yes I am aware doesn't work either way, tried 3-4 bulbs including the standard bulb I took out. All bulbs work fine in passenger side OK.

 

[ugstang17]

So which lights are you referring to? There are overhead map lights (aka dome lights for us old guys), and then there is interior floor lighting that I will refer to as "mood lighting". How about distinguishing with some detail as to what you are working on. I may be able to at least reference an older schematic and see how the lighting strategy works. It's not always the magical fuse causing the problem. It is also possible that you have a bad body control module if it is interior lighting aside from overhead map lights. A BCM is responsible for the interior lighting in the floor, cupholder, etc., on the 14 and I would not suspect that this would change much though I have no 15+ schematic to verify against. Providing specifics and being CLEAR on what you have done will only benefit you, save time, and provide a better resolve.

 

[Fordever]

Hi all, I have posted a question on FB and a few other sites but no one can seem to answer this.
I installed some LED bulbs in my 2017 GT, actually built in 2018 but 17 shape. Passenger one went in fine driver I must have shorted as it no longer works. Tried known good bulbs but nada. I see other 2017 owners say its a fuse and called on demand lighting in fuse location 1. Issue is I don't have a fuse in location one. I believe this is the case of all 2018 Mustangs. Where the hell is the fuse then. My Manuel says location 1 but I assume its a 2017 manual, even tho my car was manufactured in 2018. Any help greatly appriciated. Odd passenger map light works but not driver...must be on different circuit ? Its a right hand drive UK car. So passenger on left side etc. .

Please please help its driving me mad.

Check with a multimeter from each side of the contact where the bulb is inserted, for voltage and a good ground connection. One side should show 12+ volts, if the fuse isn’t blown, and the other side should see a good connection to ground(chassis). You may just have a faulty socket or cold solder joint on the socket. As you didn’t mention any other electrical/lighting issues, it seems weird that a fuse would only be powering one interior light. That’s why I would check my wiring thoroughly. Good luck.

 

[Swanny78]

So which lights are you referring to? There are overhead map lights (aka dome lights for us old guys), and then there is interior floor lighting that I will refer to as "mood lighting". How about distinguishing with some detail as to what you are working on. I may be able to at least reference an older schematic and see how the lighting strategy works. It's not always the magical fuse causing the problem. It is also possible that you have a bad body control module if it is interior lighting aside from overhead map lights. A BCM is responsible for the interior lighting in the floor, cupholder, etc., on the 14 and I would not suspect that this would change much though I have no 15+ schematic to verify against. Providing specifics and being CLEAR on what you have done will only benefit you, save time, and provide a better resolve.

Hi apologies its the over head map lights. It's a convertible too so it's in same overhead console as the motion sensors and roof control switch They all work too.

 

[Swanny78]

Check with a multimeter from each side of the contact where the bulb is inserted, for voltage and a good ground connection. One side should show 12+ volts, if the fuse isn’t blown, and the other side should see a good connection to ground(chassis). You may just have a faulty socket or cold solder joint on the socket. As you didn’t mention any other electrical/lighting issues, it seems weird that a fuse would only be powering one interior light. That’s why I would check my wiring thoroughly. Good luck.

I'll try that. My friend has a multimeter so will borrow and revert back.

 

[ugstang17]

You do understand that LED's are polarity sensitive correct? They are a diode that glows. For a diode to forward bias (turn on) A positive potential must be felt on the anode and a negative on the cathode. This forward biases the diode allowing current flow. The opposite reverse biases the diode and opposes current flow. Make sure you have the 12vdc positive on the anode, but first verify that you have 12vdc at the source with a multimeter. Then check the other wire to ground to ensure you don't have an open circuit. This can be verified by measuring resistance of the wire to ground. Reading 2ohms or less to ground will indicate a good connection. Good luck.

hmmmmm...

 

[ugstang17]

Hi apologies its the over head map lights. It's a convertible too so it's in same overhead console as the motion sensors and roof control switch They all work too.

No problem. There is an additional fuse panel on the passenger side. It is likely in the kick panel. Inside that panel F1 is a 10A fuse called "demand lamps" whatever the %$^& that means. I assume this would be the interior lights since there is no fuse called such on either fuse panel and you were originally referenced to check F1 which is in that panel and called "demand lamps". You can find this on page 207 of the 2017 manual. I doubt this is your problem however. My guess is.........assuming the map lights are wired direct like the 1-14 preceding model, you have a pushed pin on the socket the holds the lamp, a broken wire behind the socket, or something wrong with the switch associated if there is one.

D%$N! I wish my 2017 manuals would arrive so I could effectively go deeper in this circuit with you. I put in a request order for them with the dealership and have not heard back. But that is my problem not yours.

 

[Swanny78]

Hi thank you, yes the fuse panel is is the footwell. In location 1 where a fuse is supposed to be there is nothing. Thru my investigations so far this is true of all MY18 Mustangs which is odd. There is no listing for on demand lights in 18 manual I found on line. The manual I got with the car was a 17 and does show on demand lights in socket 1....but as I day nothing there when I looked. It could be they are wired direct as you say. I've check with a multi meter but got 0 reading ,that just could be me tho.

 

[ugstang17]

When I said wired direct I was referring to not going through a body control module like the interior lighting in the floor boards and cup holders and others do. They have to be on a fuse somewhere or fed through a body module that us ultimately fused. The 14 which has likely little relevance but the only schem source I can locate shows the map lights fed from one fuse through the interior lighting circuit on the SJB (smart junction box) and through the battery saver circuit of the SJB when the overhead switches are bypassed on so the lamps go out after 10-15 minutes or whatever that delay relay is set to.

Sorry I cannot help you further. Crap like this really bugs me knowing that if I had the schem we could work right through this with a multimeter in no time...assuming the car isn't an 18 platform wiring config that may have changed.

 

[Fordever]

hmmmmm...

I guess this is for my benefit. Point taken.....

Merry Christmas

 

[Swanny78]

I guess this is for my benefit. Point taken.....

Merry Christmas

Not sure I understand did I miss something .


Merry Christmas too.

 

[Fordever]

Not sure I understand did I miss something .


Merry Christmas too.

You highlighted part of your quote after I kinda paraphrased what you said, unbeknown to me. So I thought it was meant for me, as I was kinda confused as to why you would do that and add the “hmmmmmmm”

 

[Swanny78]

You highlighted part of your quote after I kinda paraphrased what you said, unbeknown to me. So I thought it was meant for me, as I was kinda confused as to why you would do that and add the “hmmmmmmm”

Was not me. .... ? Was other poster I think.

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