P38 Brake Light Switch ABS Fault Traction Failure.

All - just to flag up ( and raise a few serious question marks) over a P38 occurrence that I have just resolved.

Scenario:

I am owner of a 2001 P38 DHSE.
Its a great car: luxurious, durable and attractive.
The dashboard tells me everything I need to know and more: from bulb failures to the status of the doors, split interior temperatures to the name of the song I am listening to .

SO WHY WHY WHY ....WHY doesnt it tell me that the brake lights have failed when the switch has packed up?????????

OK so I drive to Wales from London in torrential rain. Driving back (again in rain of biblical proportions) she bleeps at me twice and flashes a message "ABS Fault Traction Failure" and two small warning lights come on.

I pull over - brakes working fine and vehicle has plenty of traction. So I proceed carefully down the M4 in difficult conditions until home reached. No change - fault still showing. Hmm sounds like a ££££ experience at the garage.

So i research on this site and find a couple of postings about this subject. Brake light switch failing can cause ABS Fault etc £5.70 XKB100170 etc etc Check your brake lights etc etc.

Sure enough lo and behold I have driven 130 miles on a flooded motorway with NO brake lights and no bulb failure or other alert from my "clever" car.

2 days later XKB100170 courtesy of RST Landrover spares drops through my letter box and 10 mins later the brakelights are working and the faults have all cleared.

Thanks LR for a monumentally flawed piece of designed obsolescence and the most mental piece of electrical engineering I have ever encountered!

Moral of the tale:

If you P38 shows "ABS FAULT TRACTION FAILURE" then there is a very high chance that you have NO BRAKELIGHTS!

STOP - get a new switch fitted asap. Its a dirt cheap part that controls a critical function of your car. But your car wont tell you it has failed!!!
It will however tell you that you are nice and warm and listening to Radio 2.

So that's alright then!!

The bulb failure warning is just that, it warns of a bulb failure, what do you want, fecking miracles? It can't tell if the switch is broken but if you use your eyes you can, brake lights can easily be seen in the rear view mirror in dark wet conditions.

If it doesn't know when you are pressing the brakes - how is it to know it is fecked....

Yes some high line switches have feedback circuits built in o them, but you ain't gonna find them on a car....unless you pay SERIOUS cash for it!

The door open is activated by a switch isn't it???

defender300td1 said:

The door open is activated by a switch isn't it???

Click to expand...

Yeah - but if that switches fecks up - it won't know its fecked it'll just think the door is still closed so won't show a fault - now if the switch had a self monitoring circuit so it would know it's state and then compare it to another switch it will then know that it is in fault and then issue a message to that affect....

But a switch is either on or off - unless you tell it using some form of logic circuit and compare it against a known set of criteria - it will never know if it is in the correct state for a given mode....

Saint.V8 said:

Yeah - but if that switches fecks up - it won't know its fecked it'll just think the door is still closed so won't show a fault - now if the switch had a self monitoring circuit so it would know it's state and then compare it to another switch it will then know that it is in fault and then issue a message to that affect....

But a switch is either on or off - unless you tell it using some form of logic circuit and compare it against a known set of criteria - it will never know if it is in the correct state for a given mode....

Click to expand...

Ah that explains it Ta hope you get yours sorted no smoking !

defender300td1 said:

Ah that explains it Ta hope you get yours sorted no smoking !

Click to expand...

No chance - gave up in Sept 2008 - but still I will be using a bit of red and white tape across the front to keep people out!!

Not looking forward to it, but reading and re reading the internet articles and stuff, gives me hope...

The only thing I am not looking forward to is draining the tank....