yes, disconnect the signal wire to the VQM,

https://www.fullfatrr.com/forum/topic52063.html

So I bought myself a ctek myself 5.0 yesterday and charged the battery all night and after a long drive today (1 hour plus) in ideal start/stop conditions it didn't work once. No errors popped up on the ctek which I'm assuming means the battery is OK. I'm stumped why this isn't working for me, I know it has the potential to work as it worked once a few days after I bought the car!

*Ctek MXS 5.0

How old is your car? does it have the Aux battery or a capacitor? If its the aux battery then it could be that its drastically low or dead. if this is the case the ASS is unlikely to work as the electronics use this leisrue battery to provide assistance to all the
important systems that run in the back ground and protect them from surges and voltage drops etc... during the ASS feature.

The main battery could have full voltage but if the little aux batt is low then ASS is disabled, they both have to be in range of the right voltage before ASS will work and then it will only work if there is not a high electrical demand from the car such as heated wheel, heated seats, high AC fans, etc (see further up this post for more on this.

If the it is the aux batt and its really low then the car will "top up" the main battery first and then the BMS will start charging the little guy, which if low could take a while! (might be worth charging that one overnight)

If it has the capicitor instead of the aux battery then it could just be the main battery is on its way out and whilst the CTEK has charged it up to full (it doesnt mean that the full charge has enough amps to run the systems and the ASS) If the battery has lost some of its punch over the years then it might not meet the BMS requires on volts and AMPS to run ASS

If the last point is true then it might be worth using the CTEK in AGM recon mode and see if that has any effect, but if the main battery is near 5yrs old then might just be easier to swap it with a new one and then us the CTEK to maintain it, thats what im doing.

Good luck but ou are not missing out on much to be honest! But i know what its like if something is supposed to work then it should! If a jobs worth doing, get a someone who knows what they are doing to do it!

RRS Autobiography Indus
RR P38 HSE V8
RRS Supercharged Santorini
AMG CLK Rear Tyre Shredder

Thanks for your reply mate. Erm it's a 2016 model and I checked in the boot and there's a capacitor in there not an aux battery. I've just put the charger on again tonight and put it in recond mode see if that makes a difference.
Hah i know its not an essential feature its just doing my head in why it's not working, all the other cars I've had for the past few years had it so seems odd when it doesn't shut down at the lights now

let us know how the Ctek fairs on reconing the battery. If its the origininal battery which i reckon it probably is its ont he cusp of its warranty life span, so it might be worth see if thats an option, that sais I dont reckon LR are likely to hand over a new battery for free as its now second hand car etc... all the excuses, or they will but will charge to swap it over!

Might just be the main battery is on it way out, interested to see how the Ctek recons it if it starts working again after. If a jobs worth doing, get a someone who knows what they are doing to do it!

RRS Autobiography Indus
RR P38 HSE V8
RRS Supercharged Santorini
AMG CLK Rear Tyre Shredder

Hallelujah! After a one minute warm up the start/stop worked perfectly everytime. It also cleared my airbag warning light and discovered that also apparently my spare tyre pressure is low.
Battery recond mode seems to have saved the day but it says it should only be used once a year so may not be able to save me if it stops working again

Great news then if you use the quick connector that comes with them (you will also need the extension cable, you can connect it to the battery in the boot and then feed the connector up through the wheel well and out to either side of the boot floorjust by the cargo eyelets. This way you can plug in the charger inside the boot and just run a lead out to the car and place under the rear of the car if its raining leave on overnight.

Mine is in a the garage and its a ball ache to keep popping the bonnet for me, other have manage to stretch the lead to poke out the top of the bonnet to do the same.

I reckon as long as you keep it charged on a regular basis you might be ok then (dont forget to change the setting on the CTEK as it remembers that last setting).

I did the batt change anyway as piece of mind if I went away somewhere, I know the battery is good for it.

Good news though now you can get annoyed at the ASS kicking in at roundabouts and when parking its great fun just like being a learner again! If a jobs worth doing, get a someone who knows what they are doing to do it!

RRS Autobiography Indus
RR P38 HSE V8
RRS Supercharged Santorini
AMG CLK Rear Tyre Shredder