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Courtesy lights do not automatically switch off/ECUB#4 Fuse

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  • Courtesy lights do not automatically switch off/ECUB#4 Fuse

    I am having issues with my battery going flat after not using the car for three days. One of the causes of this is that I often use the rear drawers as a work bench and have the tailgate open, I have a project I am working on away from home and this is very convenient. However, having the tailgate open means the interior lights come on and sometimes I leave the doors open as well and the courtesy door lights stay on. According to the car manual these lights should go out automatically after twenty minutes, they don't. Sometimes these courtesy lights stay on for three hours. This is not the first time I have had problems with my battery going flat, when the car was eighteen months old it went flat (I later discovered the battery was fine and I still have it) so I replaced it with a new one. The new battery went flat on a road trip three days later. Fortunately I have a 110amp auxiliary battery that I am able to jump start from but this is not the point, I have electrical problems. I also have a raft of electrical accessories fitted to my car, all fitted by qualified auto electricians. My recent encounter involved leaving my car with an auto electrician for three days to investigate the issue and $275 later nothing really has been resolved. The only positive theory was that I may have a problem with the ECUB#4 fuse circuit. My car is now 4 months out of warranty and there is a prospect of major expense replacing computer components. My other option is to replace all my interior lights with LED which is cheaper and more efficient to run but I am concerned the electrical problem will not go away and I will be stranded one day somewhere remote without electrics, can anybody help?

  • #2
    I have plenty of wiring diagrams , but an issue like that is hard to find. There are LED globes you can use to replace the factory lights , thats not a problem. And yes the lights are supposed to turn off after 20 mins , thats programmed into the ECU. If something re triggers them they start the timer again.
    to eliminate the interior lights as being a problem , try removing all the globes and see if the problem goes away.

    Interior Lights (RHD) with connectors.pdf

    ive attached the wiring diagram for the interior lights.
    2019 GX , in White


    • #3
      Thank you White One for the wiring diagrams. The interior lights are a possible cause although the problems started after having a RedArc BC/DC and auxiliary battery fitted, I have many other RedArc items fitted as well and I have every confidence in the RedArc product, I am not so confident in the people who fitted them. Again, thank you for your help.