4Runner weak battery and flickering lights

Hi, I've got a 2000 Toyota 4Runner with a gasoline engine, and I'm experiencing some weird battery issues. It only has 79763 km on it. When I start the engine, the battery seems weak, and I've also noticed weak or flickering lights, especially at idle. My vehicle diagnostics suggest it's a bad battery sensor. Has anyone else run into this?

4 comment(s)

I had a similar problem with my 4Runner. Although mine is a newer model, it sounds like a defective voltage sensor. Have you had the battery properly tested, including a load test? Low voltage readings can often point to the sensor malfunctioning and throwing off the entire electrical system.

Thanks for the insight! I haven't done a load test specifically. Could you elaborate on how the battery sensor affects the electrical system? Does it only measure the voltage, or is there more to it?

It's more than just voltage; these sensors often manage charging cycles and communicate directly with the ECU. A faulty signal can cause the alternator to undercharge the battery, leading to the symptoms you described. I strongly suggest getting the sensor replaced at a workshop; I reckon it will cost you around 315€.

Thanks so much for the advice! I took it to a local shop, and you were spot on – the battery sensor was defective. Replaced it, and everything is working perfectly now. I really appreciate the help!

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