GS300 Electrical Fault

en_passant · October 4, 2023

Hello all, I'm a long-time watcher, finally taken the plunge and signed up!

I have an '99 IS200 (which I will unfortunately have to sell due to it not being ULEZ compliant and my living inside the M25) and also an '06 GS300.

My GS300 has had problems for quite a while, meaning I haven't driven it as much. However, due to ULEZ, the IS200 isn't feasible to keep driving so I really need the GS300 working and so I have had a go at getting it up to scratch.

Basically, the Battery was completely dead. I had to use my NOCO booster every time to start the car and disconnect the negative when not in use to try to preserve the 20-30% life it had in it. I believe the Battery went dead due to it being charged/ discharged too many times.

So, I replaced the Battery and set about trying to find the drain. I had the amp-clamp around the neg lead of the Battery with the car completely off and observed approx 0.65-0.75A. I ensured the door and hood switches were seen as closed by the car then went around checking for voltage across every fuse, with none of them showing voltage across them. I also went around pulling every fuse to see if that would get the draw to drop but it was still there.

I also tried removed the cable for the alternator, to see if that would get it to drop but still nothing (I have highlighted the terminal I removed - I think I got the right cable but am not certain):

I have got the stage where I don't know what else to think / do. I'd really appreciate any help on whether someone has seen this before or any known causes - or just any guidance at all would be greatly appreciated as driving the IS200 is costing me a small fortune that I don't have!

Nice to meet you all and thanks in advance for any help whatsoever,

E_P

ColinBarber · October 4, 2023

Did you pull all fuses in all fuseboxes? How long was the car left off before measuring the current as it may need time to go to sleep?

Herbie · October 4, 2023

2 hours ago, en_passant said:

I also went around pulling every fuse to see if that would get the draw to drop but it was still there.

Never pull fuses when looking for a parasitic drain. You need the car to be completely 'asleep' but pulling fuses could wake up something and give you a false positive.