why is it permenent live?

macafee2 · 5th January 2021, 13:16

According to my owners manual of my facelift CDTI, fuse 47 in the passenger footwell is Traction Control.
I don't have traction control but testing 47 it is permanent live, why would it be live when the engine is off, what is the point?

macafee2

clf · 5th January 2021, 15:30

Quote:

Originally Posted by macafee2

According to my owners manual of my facelift CDTI, fuse 47 in the passenger footwell is Traction Control.
I don't have traction control but testing 47 it is permanent live, why would it be live when the engine is off, what is the point?

macafee2

at a guess, it would be a simple cost matter. The wiring loom would be standardised up to the fuse box. It is then a matter of fitting a loom with a traction control (or other options ticked when ordered) and then fitting the fuse. to complete the relevant circuit.

It is permanent live simply because that is the way it was designed. I dont see the point of it being so, as it is not required if the car is not moving, but may come down to some form of diagnostic purpose. Also I believe it is linked somehow to the ABS, so it could have some safety reason too - related to the ABS rather than the TC itself. If the engine cut out at speed, for whatever reason, the ABS would still be able to do its job - traction would not be used of course with no power, but the ABS would still be available.

COLVERT · 5th January 2021, 17:12

Take it out and see what it does.---

SD1too · 11th January 2021, 08:07

Quote:

Originally Posted by macafee2

... fuse 47 in the passenger footwell is Traction Control ... it is permanent live, why would it be live when the engine is off, what is the point?

Hello Ian,

That's a good question. Looking at the wiring diagram it appears that the feed you've identified is used by the ETC ECU to supply its servo motors. The wires for both are quite thick so the current will be large. That will be the reason why it's not wired through the ignition switch.

Simon

macafee2 · 11th January 2021, 09:02

Quote:

Originally Posted by COLVERT

Take it out and see what it does.---

I have used it for part of my towing electrics. I can't recall why I did not use 22 which shows in the handbook as Towing Accessory. Sitting here thinking, I'm not sure why I did not used a switched live. Perhaps the towing relay needs a permanent live but it does not seem to go on to supply power to the caravan unless the engine is running.

macafee2

raykay · 11th January 2021, 10:01

The contact supply to the towing relay is direct, but the coil supply is ignition controlled, so the output from the relay is only 'On', when the ignition is 'On'.

5th January 2021, 13:16	#1
macafee2 This is my second home Rover 75 Saloon & Tourer Join Date: Sep 2012 Location: Lincoln Posts: 14,912 Thanks: 1,630 Thanked 3,032 Times in 2,181 Posts	why is it permenent live? According to my owners manual of my facelift CDTI, fuse 47 in the passenger footwell is Traction Control. I don't have traction control but testing 47 it is permanent live, why would it be live when the engine is off, what is the point? macafee2

5th January 2021, 17:12	#3
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	Take it out and see what it does.---

11th January 2021, 10:01	#6
raykay I really should get out more....... Now Other Manufacturer Join Date: Nov 2006 Location: Co. Kerry Posts: 2,786 Thanks: 16 Thanked 310 Times in 283 Posts	The contact supply to the towing relay is direct, but the coil supply is ignition controlled, so the output from the relay is only 'On', when the ignition is 'On'.