Spudey

Thanks - yes i get the impression there are no good used modules around on ebay or breakers because they cause so many issues. The module has been revised a few times too i think in the last 10 years - hopefully more reliable now. Also for being an MQB platform car this module seems to have different part numbers and pin layouts across the various vag brands - so i wasn't confident enough to use one that 'looks' the same from Audi or VW in case the programming is incompatible. Thanks - That is the problem with these electrical gremlins - often simple fixes but takes a lot of time had head scratching to find the issue in the first place. not so good when diagnostic sessions cost an arm and a leg. I would like to think the more senior dealer techs may be more aware of common faults and be able to use experience to get it done faster, however I've not often found that to be the case at many main dealers i've visited in the past.

Hi All. Just wanted to update this thread for closure in case it helps anyone in future. I learned the two cable running from the fusebox (Black & Red) are actually both live feeds going to the left and right side of the car for various modules, so not much helo there. Further investigation revealed that disconnecting the power tailgate (Fuse 22 Luggage compartment door opening) did allow the car to go to sleep. I located the module in the boot behind the left interior trim, disconnecting the output side still gave me issues so i though I had a problem in the module itself (Control Unit for Trunk Lid, p/n 5E0 959 107A). I removed it and inspected inside and sure enough visibly identified a blown component on the board. New part ordered from Skoda for £225 (no good used ones available for a more reasonable cost). fitted and all working again perfectly - no more battery drain issues overnight.

Hi Aperture, Thanks for the confirmation of this and your comments re. troubleshooting. I think i'm on the right path but will see if I can get any more clarity on whats going on over the weekend. Until then I have a trickle charger going on every night to stop the battery being repeatedly depleted too far.

Hi All, posting my troubleshooting here in the hope someone can lend some insight into what is going on with my MY2015 Octavia mk3 VRS TDI combi. I've tried to be sensible and thorough with my process so far but reaching the limit of my available skill and patience at the moment. 🤯 About 2 months ago the battery started to go flat, initially blamed by son for leaving the door open and draining by the interior light. Jumped it back to life with another car but after a few days i had the same problem. It would struggle to start after being parked for a day. 2 days would require a jump. Battery was 6 years old and as it was draining so rapidly/deeply (3 volts at one point) i replaced it with a new Yuasa AGM model. I had drain issues back then and the new battery fixed it so suspected the same here. Programmed the make/type/capacity/S/N to the car with OBD Eleven. Drain issues continued, also had some simultaneous failure of my reversing camera (Cheapo aliexpress model) and the power tailgate intermittently refusing to close (3 beeps when button pressed). Unclear if they failed by coincidence, if are the cause of the issues somehow or a result of repeated drain to low voltage and then jump starts. Started to troubleshoot the power consumption/parasitic draw and issues. Observed current fluctuation 750mA with a regular spike up to 1.2A every minute or so while car was off (locked/asleep) Firstly removed all possible power consuming additions (aftermarket reversing camera/harness, dashcam, phone charger). Removal of the reverse camera stopped the regular spike to 1.2A, so now sleep state is hovering somewhere in the 750-800mA range measured with both a clamp meter and via OBD. Investigated tailgate closure issue, no fault codes on the module but suspected a sensor failure, sure enough I disconnected the left strut sensor connection in the d-pillar (but left the power connection) and the boot now opens/closes without issue (although the disconnected sensor does throw an error in OBD Eleven) - No change to battery drain issue though. I tried to identify what components are pulling current by following the VAG bulletin method of checking voltage drop across the fuses (i know pulling fuses in these modern cars can cause more confusion than it solves as other related modules are woken/shut down as you go) - my results showing the voltage drop and calculated current draw for the components i found to be active are below, listed from largest to smallest: Also checked with clamp meter what the stable current draw as before/after removing fuses and this broadly agreed with the above results. So seems Central locking left, Central locking right and the dash are showing high current draw as well as the tailgate. If there are multiple modules active then are they being kept awake by the CANbus? If a boot strut motor is shoring out would this also keep the door units awake? or could it be a gateway issue causing current draw in multiple other modules? I logged some charts showing current draw with OBD Eleven when the car is off and showing the sequence when car is opened, ignition on, then locked again. I know having the dongle live on OBD port will draw a small current also but I haven't seen it register when checking with the amp clamp on the battery lead. Current is shown as negative as it registering draw from the battery, Also checked alternator lead from fusebox with amp clamp and disconnected it entirely to make sure - there is no current flow to alternator when car is off. There are two leads from the engine bay fuse box back to the cabin fuse box (Black and red), can anyone explain what they each do? - i would assume positive and negative from the colours but the clamp meter is showing different values on each and broadly they add up to the total draw seen at the battery lead. OBD Eleven backup file listed below in case it helps any of you VAG professors who can comprehend it. So that is my story so far. Thinking of trying to isolate the tailgate module from the system next but not sure if just disconnecting it would help or if i can code it out somehow in the OBD app. I have spent days searching online for similar situations but not turned much up so far, so my next step is to post here for any suggestions before I go down the route of what could be a expensive dealer diagnostics done. Any comments or suggestions welcome! .

Hi @pab567. Appreciate any help up upgrading my bolero firmware. Thanks.

Hi, appreciate any help on updating to newer firmware. Thanks!