Brake lights staying on but roof brake light not

[Nightmonkey]

I also have a trickle charger I must use on it every night when parking it up.

Normally, the car can stand still for several days without any problems with the battery.
Is this still the first? Manufacturing date should be recognizable on the battery somewhere.

If you have to charge every night, then there is definitely something wrong.

Do to:

1. Reset by disconnecting the battery
2. Determine date of manufacture of the battery.

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[JaybeM5]

Normally, the car can stand still for several days without any problems with the battery.
Is this still the first? Manufacturing date should be recognizable on the battery somewhere.

If you have to charge every night, then there is definitely something wrong.

Do to:

1. Reset by disconnecting the battery
2. Determine date of manufacture of the battery.

I haven’t had to charge it. It’s starts first time but when I checked the voltage in the car settings I thought it seemed lower than it should be. I would say it’s original battery. It was Ford branded when I checked yesterday not that that means anything. I’m away from the car till later so will check then.
Am I right in saying the tail lights are led and not bulbs ? I did see a cover cap on the tail light so what is that for if they’re led ?

 

[Nightmonkey]

Yes, full LED!
Completly sealed.

 

[ORRadtech]

What voltage should the battery be when driving ? In the settings it says 12.9v which seems low.

I also have a trickle charger I must use on it every night when parking it up.

Battery voltage when driving should be right around 14V. Mine sits at 14.2 very consistently. That is not actually battery voltage though, it's the charging system voltage. 12.9V, if that is accurate, may indicate a charging system problem and/or a failing battery. As said above, if you have to put it on a trickle charger nightly something is not right with the battery or the charging system.
The original batteries seem to average 2-3 years before they start to get weak. Weak batteries in modern cars will cause all sorts of erratic behavior. Messing with the brake light operation is not out of the realm of possibility.

 

[JaybeM5]

This c

Battery voltage when driving should be right around 14V. Mine sits at 14.2 very consistently. That is not actually battery voltage though, it's the charging system voltage. 12.9V, if that is accurate, may indicate a charging system problem and/or a failing battery. As said above, if you have to put it on a trickle charger nightly something is not right with the battery or the charging system.
The original batteries seem to average 2-3 years before they start to get weak. Weak batteries in modern cars will cause all sorts of erratic behavior. Messing with the brake light operation is not out of the realm of possibility.

I’ll have a look this evening and check it all out and do a reset. Car isn’t going to be driven everyday so is it recommended to put them on trickle charge then ?
I know my BMW eats the battery if left for a week without driving it. Battery needs changing every 2 years.

 

[Skye]

Car isn’t going to be driven everyday so is it recommended to put them on trickle charge then ?

I hope it's an easy fix.

You and others have been educating me on some of the electrical bits with this thread. go raibh maith agat .

I make a distinction between charger and tender.

A charger presents a constant force to the battery, with little to no intelligence.

A tender conditions or exercizes the battery, as well as charges, when needed; CTEK units are one popular brand. Battery Tender, Battery Tender Plus is another well-liked one.

A trickle charger could help you for now. Long-term, it's best to migrate to a tender/maintainer.

Agree with others: the car's battery should hold a good change for several days, if not a few weeks, by itself.

 

[JaybeM5]

I hope it's an easy fix.

You and others have been educating me on some of the electrical bits with this thread. go raibh maith agat .

I make a distinction between charger and tender.

A charger presents a constant force to the battery, with little to no intelligence.

A tender conditions or exercizes the battery, as well as charges, when needed; CTEK units are one popular brand. Battery Tender, Battery Tender Plus is another well-liked one.

A trickle charger could help you for now. Long-term, it's best to migrate to a tender/maintainer.

Agree with others: the car's battery should maintain a good change for several days, if not a few weeks, by itself.

Go raibh maith agut Skye The one I have is a CTEK MXS 10. I find it very good. I use it on my F10 M5 all the time when it’s not in getting fixed but that’s another story

 

[ORRadtech]

I hope it's an easy fix.

You and others have been educating me on some of the electrical bits with this thread. go raibh maith agat .

I make a distinction between charger and tender.

A charger presents a constant force to the battery, with little to no intelligence.

A tender conditions or exercizes the battery, as well as charges, when needed; CTEK units are one popular brand. Battery Tender, Battery Tender Plus is another well-liked one.

A trickle charger could help you for now. Long-term, it's best to migrate to a tender/maintainer.

Agree with others: the car's battery should hold a good change for several days, if not a few weeks, by itself.

It's all semantics. They're all chargers. But like any other tool some are designed for different specific purposes. I have several chargers from large, 50A ones to trickle chargers. And a trickle charger is just a hold over term from when low output chargers didn't have enough electronics to navigate space craft...
Any modern vehicle, with a healthy battery/charging/electric system should be able to sit for several weeks- 3 or 4 at least - without going flat. But since all modern cars have various things that constantly draw current (alarms, clocks, keyless entry, monitors, etc) they will eventually go flat. Any vehicle that goes dead in a week or less has a huge parasitic draw, a failing battery or a poor charging system or a combination of all three.
Troubleshooting any electrical issue requires a good, constant power source. The very first thing any competent technician will do when troubleshooting an electrical gremlin is connect the battery to a charger.
The OP's tail/brake light issue may, or may not be related to the battery/ charging system but until that is fixed/confirmed any other attempts to locate the problem would simply be randomly shooting in the dark.
My suggestion to the OP is, despite the trip and small roads, to take it straight to the selling dealership and avoid adding any extra layers of complication.

 

[JaybeM5]

Ok battery was at 13.7v after an hours drive home. I disconnected the battery for about 15-20 minutes and no difference to the lights.
I can’t see the date on the battery. It’s etched into it but unrecognisable.
Next step is diagnostics but I won’t be available to do that until early next week.
Hopefully something will show up if not I’ll be bringing it back to the dealer to let them sort it out.

 

[JaybeM5]

Update on this. I disconnected both tail lights and plugged them in one at a time and quickly realised one worked perfect but once I plugged the other in the brake lights would stay on. Got onto the Garage and they sent me a new tail light and it fixed the problem thankfully.
Can these tail lights be split like the headlights so I can try fix the issue and have a spare one ?

 

[Nightmonkey]

Must be sawed open and plastic welded afterwards, as far I know.

Find a cheap used pair there: https://www.kleinanzeigen.de/ (use Chrome translator)
https://www.kleinanzeigen.de/s-mustang-rückleuchten/k0
https://www.kleinanzeigen.de/s-mustang-heckleuchten/k0

shipping to Ireland should not be a pain.

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