sorcerer

It's good that you found them at a decent price but they aren't actually needed and many people just do away with them when they start to give problems. Sent from my SM-T520 using Tapatalk

Previous keeper details will be on the V5C (log book) when you get it. I always contact the previous keeper to see if they were having any problems with it etc.

Maybe I'm being a bit simplistic but surely, all you need to do now then is to adjust the mechanical brake light switch so that it switches the lights on at 1mm depression and that would be it sorted wouldn't it?

A car engine has to go through its operational cycle in order to start. To 'crank' an engine means to turn it by external means, such as a crank handle in the old days or a starter motor in modern cars. Once the engine fires up, whatever was used to crank it becomes redundant, so in the case of a starter motor, you release the key when the engine fires, thereby shutting off the power supply to the motor and it stops spinning. A switch is just a device that, if you move it to the 'on' position or 'close' it, it will 'make' the circuit and when you move it to the 'off' position or 'open' it, it 'breaks' the circuit. When you turn the key through the IGN position and on to the START position a few things happen, but in the context of this thread you're basically just closing a (low power) switch that energises an electromagnetic switch (the solenoid) which then pulls in a big, beefy set of contacts (a high power switch) and allows high battery current to flow to the starter motor and makes it spin. When the engine fires and you let go of the key, that opens the low power switch and cuts off power to the solenoid, which in turn should open the high power switch and stop the flow of high battery current to the starter motor so that it stops spinning. Because (we think) that the solenoid contacts have welded together, letting go of the key has no effect. The solenoid contacts can't open so battery power is constantly being supplied to the starter motor and causing it to spin continuously, so the noise of the motor turning is what you're hearing.

A valiant effort Nigel but that relay was never going to be the problem - it's a small relay, drawing a small current that's used to switch the much heavier current at the solenoid. As I mentioned earlier, a starter motor draws a minimum of about 300 Amps so it's at the big, heavy contacts at the solenoid end where the arcing takes place and where they can eventually weld together.

It's certainly turned into quite a saga Nige! This is from the American forum and it relates to an RX330 rather than our RX300s, but it should help: https://www.clublexus.com/forums/rx-2nd-gen-2004-2009/596123-rx-330-yaw-sensor-location.html

Just looking through my historic postings for something and came across this from March - I knew someone else had had a problem with it

You're very welcome Nigel, hope you get it sorted without too much hassle. Good luck!

I suppose it could be, but it's not very likely and I very much doubt it. The most likely scenario is that the starter solenoid contacts have welded together so that you now have, in effect, just one big wire directly from the battery to the starter motor, which is why you get sparks and the motor runs when you connect that wire to the battery. If you do want to try looking for problems with the ignition switch, or if you want to prove beyond doubt that it's the solenoid, you really need a multimeter for proper testing. Quite a decent one can be had for about £25-£30 but even a cheapo one at about a tenner would do. Easiest thing is to check for continuity on that big wire that you connect to the battery. Switch the multimeter to measure resistance or to its continuity buzzer if it has one, put one croc clip on the wire at the battery end* and the other croc clip or probe on the starter motor +ve terminal and I'll bet a week's wages that either the buzzer will sound or the meter needle will swing all the way over to the right (or give a reading of either zero or close to zero if it's a digital readout). The solenoid is just a big switch so if it was working properly you wouldn't have continuity but I think you'll find that you have. * Sorry if this sounds condescending but I don't know your level of electrical knowledge so, just remember that you're only looking for continuity, not voltage, so don't connect the wire to the battery when (if) you do this test.

Welcome to the Lexus Owners Club Nigel I don't have an LS400, I'm not a mechanic and I'm not an auto electrician, so hopefully someone more knowledgeable than I will be along soon. In the meantime, for what it's worth.... I think the problem was initially a faulty or dying starter solenoid. When you turn the key, a small current is applied to the starter solenoid, which then electromagnetically pulls in a heavy set of contacts to allow a large current to flow to the starter motor (when cranking a starter motor it's almost like putting a direct short circuit across the battery and the motor will draw 300 Amps or more). The coil of the solenoid may have gone faulty and was not pulling the contacts in strongly enough, or maybe there's a loose connection to it or something. Either way, with a minimum of 300A flowing there will have been a lot of arcing and now the solenoid contacts seem to have welded themselves closed, thereby allowing continuous current flow to the starter motor and why it's running all the time. Some cars have a separate starter solenoid but it's more common now I think to see it integrated into the starter motor and I'm afraid that I have no idea which way it is in the LS400. Hope you get it sorted quickly and cheaply, whatever it turns out to be.

The reasoning of Occam's Razor would say that the previous owner took out the white bulb/LED and replaced it with a red one, disconnected the reversing light feed and wired it up as a second foglight. Maybe.

You're not kidding Paul! Thing is, it's the magic smoke that makes things work - once that magic smoke escapes, that's it, it's broken

It's true that you won't want both the DRLs and puddle lights on when actually driving but there's also the other side to consider too. You'll have a 'normal' power feed to the DRLs for them to work in the normal way, but when you take your 'new' power supply to them, that 'new' power will also backfeed up the 'normal' wire to who knows where, so you need to stop that too. Auto electrics are a very strange beast. I remember a situation where every time a lorry driver put his foot on the brakes, the windscreen wipers came on. If I remember correctly it turned out to be a faulty earth connection somewhere allowing power to find an earth path through a different circuit.

Ah right, fair enough. So essentially you're going to provide power to the DRLs when they aren't meant to be powered up. Just be aware that cars that are wired from the factory to have the feature you want may have some electrical wizardry to stop power backfeeding into other circuits whereas yours won't have that.

I'm still intrigued. You say it's to power LED DRLs but you also say "even when car is locked" - by which I'm assuming you mean parked up and locked, with the engine off, in which case you won't need DRLs???

The first time we drove to Czechoslovakia was in 1991 before it became two separate countries again (Czech Republic and Slovakia; in 1993 if I remember correctly). At that time there was only one company producing a guidebook (Fodor's) so almost all tourists were turning up at the same places. We spent some time in a beautiful little place called Český Krumlov and we were very surprised to see, outside the hotel, a UK-registered Morris Minor with a split windscreen, which I think ages it to before 1956-58ish when they went to the single-piece windscreen, so it would have been at least about 33 years old when it did that road trip. It's still the oldest UK-registered car I've ever seen on the road abroad.

Get yourself out to Poland, Czech Republic and/or Slovakia. Some absolutely beautiful places with warm, friendly people - and beer at 85p/pint

Sorry, can't help with fuse allocation but why not just go and buy a multimeter anyway? Even very decent ones can be had for about £25 with cheap ones being under a tenner. Once it's bought, you have it for future use as well as now.

No doubt they have a chart on the wall like most places do and they only fit what the chart says should be fitted.

Thanks folks, all very informative and I appreciate it. @steveledzep did you get yours from a Lexus dealer or an independent?

Cheers Steve, good to know that maybe my budget will stretch to a 2013 model and your mpg info is very interesting, so thanks for that too.

I believe that the third generation RX450h was facelifted in 2012, where it acquired the spindle grille amongst other things. Hopefully, I'll soon be in the market for a 3rd Gen RX450h and I was just idly wondering if fuel economy was somehow improved in the facelifted version or was it mostly a cosmetic makeover? Don't get me wrong, I'm not tight and I do know that the RX is a big car and drinks fuel for fun, having owned an RX300 for about 20 months now. However, I just don't like wasting money if I don't have to. Plus, I may be able to convince my good lady wife that we should perhaps spend a bit more on the purchase of a facelifted model if it's going to be better and more efficient on fuel than a pre-facelift one. We should have a budget of £20k which I think puts us in the 2010 to early 2013 model years (perhaps being a bit optimistic including 13 in there unless I'm very lucky) but may be able to increase that slightly if the facelifted model justifies it.

Of course you didn't Dan, no apology necessary at all my friend - and thanks, so do I

Many years ago I had an accident at work that resulted in a back injury that was bad enough to see me medically retired from a job I loved. I've also had a triple heart bypass and bladder cancer (so far been clear for two years now from that). With a track record like that, I sometimes think that I'm not going to make it into my late 70s/early 80s but who knows - I may have gone through the worst now and not get anything else so serious I currently drive an RX300 and it's perfect for my back problem. The seats give me plenty of support and the extra height makes it so much easier to get in and out of, it's the perfect car for my needs. The vast majority of my working life was spent as a telephone engineer (cable jointer) on Post Office Telephones/British Telecom/BT, so driving a variety of different sized vans over the years means that I'm very comfortable with driving larger vehicles and don't find the RX any problem at all. Plus, we need every inch of boot space when we drive over to Poland/Czech Republic and other eastern European countries for our holidays because we're usually away for about four weeks at a time. It's definitely an RX for me

Definitely the water supply pipe for the rear washers - someone else had this exact problem a while ago.