Delphius1

I'd make sure the 12v battery is fully charged. It's the time of year when we all start turning on the heater fan up to full to demist and the screen/mirror/seat heaters go on. i.e. it's puts more strain on the 12v battery. It's very easy to get the battery to a stage where it doesn't have the oomph to unlock the latch and work the tailgate (it's takes quite a bit of current to do the job). On a hybrid you don't tend to notice the 12v battery dying as you would with a totally internal combustion engine car. If you can, try charging the 12v battery and see if the tailgate action improves. Might save you a bit of money chasing other things when all you might need is a new battery.

Herbie, It just seemed obvious when the OP was posting about oil level, especially as it was an info screen message rather than a big red warning light! I've tracked down the sensor for the RX300/RX330, I'm guessing the RX400 should be similar or the same: https://www.lexuspartsnow.com/parts/lexus-sensor-engine-oil-level~89491-33030.html It would be worth checking the sensor is (a) connected and (b) faulty before shelling out for a new one. They don't seem particularly cheap for what they are!

I'll have to bow out of commenting on this one as I didn't have a working Lexus camera to compare against. I bought the car with a broken camera.

I'm not sure if it's the same on the RX400, but on my RX300 the oil level warning and oil pressure warning are two entirely different warnings, supplied by two different sensors. The oil pressure switch measures the oil pressure in the oil gallery after the oil pump and lights the red oil can if the pressure is low on my RX. The light is red for a reason: the engine shouldn't be run with low oil pressure. The oil level is measured by a float switch in the sump. The oil level warning light is an amber oil can on my RX300. ON the RX400 I assume the warning is in the information display. Being amber (or the information display) it means the warning is not as critical as oil pressure. You can check the level using the dipstick and if the level is okay, then get the sensor changed. Regarding the Original Posters comments, they've got an oil level warning, but changed the parts that sense oil pressure. They changed the oil pressure switch and the oil filter, but not the oil level switch, which is completely different. No wonder the fault is still there. The oil level float switch in the bottom of the block needs changing.

It's nice that 18 months after I posted it, this thread is still helping people. Must be the most helpful thread I've posted anywhere. :-)

There's no direct replacement/upgrade as far as I'm aware. You could look into one of the modules that plugs into the external CD changer socket on the original ML head unit and gives you Bluetooth. The main bugbear with closed systems like the ML one is that the line levels and speaker impedances used in the system are completely different than standard systems. So you can't just go out and buy a head unit and expect it to plug straight into the Mark Levinson wiring and have it work. The ML head unit drives and amp under the rear seats, which then drives the completely non-standard speakers. So if you fit a head unit from any of the usual makers like Panasonic, Sony, JVC, etc, then you may need a line level convertor between it and the Mark Levinson amp. You may also need a 12v feed from the head unit to the amp when the head unit is switched on, to switch to amp on and off. Otherwise you either don't switch the amp on and get no audio, or if you feed it permanent 12v, you risk draining the battery. With closed systems like the Mark Levinson one, I always recommend taking the car to a car audio specialist. They can advise on what would be required to interface a new aftermarket head unit into the existing system. That way you drive the components at the correct level and get decent audio.

Cutting and re-connecting two wires doesn't usually result in this sort of catastrophic failure. The only time I've ever seen a list of errors like that is when the battery has been connected the wrong way round or the car has suffered damage from water ingress. The only other thing that could explain it is if the wires were something like digital data signal wires where simply resoldering them isn't necessarily the way to repair the wire. The only thing I can suggest is to hook the car up to techstream so you get an idea of what modules are reporting faults. It's possible that multiple modules have lost connection to a single module and that's why you're getting so many errors. Have you disconnected the battery for 20 minutes or so to reset the car's systems? The old "turn it off and back on again!" trick might just reset all the modules so they communicate with each other again.

When you start the car, the loud noise from the open exhaust pipes where the cat used to be is a bit of a giveaway. :-)

Don't forget the gearbox and engine should be at operating temperature and the engine should still be running while checking the gearbox oil level, unlike checking engine oil.

I've just fitted budget tyres to replace the Avon zx's on My RX300. Couldn't really justify spending over a quarter of the value of the car on tyres! I fitted Three-A EcoSavers, never heard of them before, but they are Chinese (just like most budget tyres and even some premium tyres these days). C rated for economy and wet grip, 72Db on noise. I'm very happy. They are 104 load rated rather than the 100 of the Avons and I must say the car rides a bit better. I was originally offered Blacklions, but the noise, wet grip and economy ratings were a lot higher then the Three-As. I suspect they were just trying to sell them off. Wet grip was tested on the M56 last weekend in a torrential downpour. No aquaplaning and no drama when hitting patches of standing water. They just ploughed through it. Being budget tyres, I'll see what the longevity is like and how they hold up on the ratings once they get a bit of wear on them. Edited to add: I was in Australia during the winter and was interesting to see the Chinese brands Like Jinyu and LingLong get advertised just like the major European brands. There doesn't appear to be the same badge issue. If they work just as good as the major brands, then the Australians buy them.

Have a word with a car audio specialist. On closed systems like ML and Bose, the head unit drives an amp which then drives the speakers. The level between the head unit and the amp is usually different than the levels produced by standard head units. So you need a line level convertor between the new head unit and the existing amp so you drive the amp at the correct level.

The backing plate "issue" on the MOT only refers to brakes where the backing plate has a direct effect on the braking, as in the backing plate on a drum brake setup. In that case the backing plate is an integral and essential part of the brake integrity and any defect like rust (or not being there!) can directly affect braking. In disc brakes the plate behind the disc is shield and has no effect on the braking performance and isn't an MOT fail. If the tester fails it, he's reading the rules wrong. On hybrid brakes, where the inside of the brake disc also acts like a drum, then usually the drum brake will have a separate (stronger) backing plate, or the backing plate will be the actual suspension upright (because the thin dust shield isn't of sufficient integrity to support a drum brake). On the RX from the pictures in the Haynes manual, there is a separate backing plate which is not part of the dust shield. So the dust shield can be removed and the drum handbrake backing plate will not be affected. Therefore not an MOT failure. But you may have to argue the toss with the MOT tester if they don't understand. For instance how can the handbrake be working if the backing plate is missing? Having a Haynes manual handy to show them pictures may sway them.. :-) I've had it on classic cars with disc brakes where the dust shields are no longer available. You can remove them completely and still pass the MOT.

I don't mind which petrol I put in the car. Generally it's a mixture of regular supermarket petrol, with the premium stuff once a month or so. I did use a fuel cleaner once, it cleaned the system so well my mpg went from 32 to 22. It had cleaned the fuel consumption sensor so I was getting a true reading. ☹️

There is a company called Walker that produce a whole range of aftermarket sensors, coil packs, etc. They are originally a US company, but they have a presence here too. I think they are trade only and you have to go through a motor factor. I don't have their UK contact details. But it's worth checking with your local factor to see if they can get parts from Walkers. They do coil packs for the RX I'm sure they would be decent quality. I've used their coil packs and an oxygen sensor on an MX-5 before and they have worked fine. They appear to be better quality then the cheap Chinese stuff. Their US website is here: http://www.walkerproducts.com/

With the Xtrons unit, you need a reverse signal to switch the unit over to reversing camera mode. Without it the head unit won't display the reversing camera. Does your head unit switch to video input when you select reverse? If the head unit switches to a blank video signal on reverse, you need to get the camera video signal to the head unit, or the camera isn't being supplied 12v . The camera yellow lead runs to whichever socket on the xtrons is for reversing camera input. The positive of the camera goes to the reversing light positive and the camera negative goes to earth, so the camera is activated when the reversing light is on and the xtrons unit switches over when it gets a reversing signal as well.

That's a bit of a shame, doing the same on a Prius tends to solve the problem. Do you have access to Techstream at all? It may pay to get hold of it and start some deeper diagnostics. Without the ability to delve deeper into the cars electronic systems, you won't be able to see what the issue is. The problem is all the various modules have varying levels of interdependence and if it's not the BCPS that's faulty you really need to know why its throwing the code. Edited to add: Has there been any water ingress at the back of the car at all? Any wetness around the electronic modules? Water can cause untold electronic issues if it gets amongst the hybrid battery and control modules.

I'm with Herbie on this. The manufacturers don't actually make the filters. In fact in Europe, most Japanese manufacturers source filters from suppliers in Europe rather than supply all the way from Japan. It helps avoid long lead times for supply and keeps costs down. You're still getting an OEM-spec filter and it comes with the backup of the car's manufacturer. But you could probably buy the exact same filter in the aftermarket cheaper. For instance I know that Mahle in Germany supply filters to one Japanese manufacturer (not Lexus before you ask). I also agree that you should avoid the Chinese no-name filters you often see on eBay. No backup, no quality control, no thanks. My RX has a Bosch filter supplied by the local motor factor.

I'd try and run it a bit in hybrid mode and see if the capacitors are slow to charge up, then clear the code. If the code comes back straight away then you probably need a new bcps. But do check related fuses like the ABS fuse to make sure it's not as simple as a blown fuse.

On the Prius, C1378 usually points to a faulty brake control power supply. The BCPS manages the power fed to the high voltage battery under regen braking. It is powered from the 12v supply and I believe it contains a capacitor or bank of them to manage the 12v power supply when the 12v battery voltage drops, because it controls something essential like the brakes and needs a stable power supply. Don't want the 12v to drop and the brakes to disappear! If the 12v stays low for too long, the capacitors drop their voltage and throw a code. So the guys pointing to the 12v battery may be on the right track. The bad news is if the new 12v battery doesn't solve the problem, then it needs a bit of nous and diagnosis to confirm the cause of the fault code. Not sure if this is all relevant to the RX because the systems may be different between the RX and the Prius (for instance the BCPS may be incorporated into the DC/DC invertor on the RX), but it sort of informs you as to what may be causing the system to complain.

If you drove quickly through large puddles, it can create enough water pressure to force water into all sorts of places it shouldn't be, like inside sensors. It can even strip wires from sensors. ABS sensors are the most vulnerable to water damage, but it's not uncommon for other sensors to be affected. It's worth getting under the car and doing a physical check of the wiring to the sensor to eliminate obvious repairable issues like a broken wire. Many years ago I had a Ford Sierra 4x4 and drove through a large puddle. Water got into the intake and killed the MAF sensors. It affected the fuelling so badly you could see the fuel gauge dropping.....

Welland, the reason I mentioned the gauge of wire in my previous post is because the wire that supplies current to the trailer socket (and then on to the fridge and the battery in the caravan) may not be chunky enough. If the wire is too thin, then there will be a voltage drop along the wire, which means that although you get a voltage change at the battery terminals on the car, the voltage at the trailer hitch socket and then the caravan is a lot less or there is none at all. What you end up seeing is just the battery voltage of the caravan battery. In bad installations, even if the wiring has been installed specially, it can still be under-spec and dangerously thin and risk catching fire if it's trying to supply current to the caravan fridge and a discharged caravan battery at the same time. In some really bad cases I've seen caravan wiring tapped into wires in the boot, relying on the car's wiring harness to supply several amps to the caravan socket, something it was never designed to do. You need to work logically on this and go back to basics. Don't assume anything, including the fact that the wiring for charging is actually installed in the car! Check first you need to check that the car battery voltage goes from 12.5v or thereabouts when the hybrid system is inactive to 14v approx. when you press the start button and the hybrid system is active. That then gives you the base to work from because you can see the voltage jump is happening. A tired battery may not reach the required voltage. Then check you have decent gauge wire installed from the car battery terminals to the trailer socket (through a fuse at the car battery terminal of course). You then need to make sure the wire goes to the correct pin on the socket and that the voltage is exactly the same at the trailer hitch as the battery terminal. Then check the wiring on the caravan plug corresponds to the wiring on the caravan socket. I've seen installations where the pins are not matched so you can plug the caravan socket into the car, but you'd never get voltage to the caravan because the car is supplying a different pin on the socket than the caravan is wired to on the plug. It's more common than you think, because different people wired up the car socket and the caravan socket. Once you are sure you've got a voltage step at hybrid switch on, decent gauge wiring to the socket, no voltage drop, the car and the caravan connect to the same pins and you have a good connection from the car battery terminals to the caravan, then you can measure the voltage at the changeover relay in the caravan. When the caravan is plugged into the car, the nominal 12.5 volts of the car battery should not cause the relay to switch from house mode to charge mode. When the hybrid system is activated on the car (the same as starting the engine on a normal car), the voltage on the battery terminals on the car should raise to 14v-ish. The same voltage should appear at the caravan relay and it should detect this and switch over to charge mode. Pressing the button to stop the hybrid system should drop the voltage back to 12.5-ish and the caravan relay should drop out and disconnect the fridge and battery. If it doesn't then you are in danger of flattening the 12v battery which comes with it's own issues on a hybrid. Just see the number of posts on here relating to dead 12v batteries on hybrids. :-) Hopefully that should cover most of everything. I'm a bit rusty with trailer and caravan electrics, haven't done it for a few years (pre 13-pin socket era) and it changes constantly. That's another reason why the plug and socket might be wired differently: because the standards can change year-to-year.

Exactly what I was saying. The hybrid battery maintains the 12v battery and the only thing that you can detect is when the hybrid system is activated. But then that's the hybrid version of engine running on a normal ICE-only car. The hybrid battery will maintain the 12v battery in the car and supply 12v to the caravan. If the hybrid battery can't maintain a charge then the engine will come on. But the process of starting the engine is entirely controlled by the car's electronics. The big thing you have to avoid is the caravan draining both the 12v and the hybrid batteries. So there has to be some way of disconnecting the caravan electrics from the car when the hybrid system is deactivated.

An interesting problem because the 12v battery is maintained by the DC/DC invertor from the hybrid battery and engine revs have no effect on the battery voltage. There won't be enough voltage change to trigger a voltage sensing relay. You may have to check the towing socket on the car and see if you get a 12v feed on one of the towing socket pins when the hybrid system is activated. Then use that 12v feed as a signal for the caravan relay to switch between house mode and towing mode in the caravan. Check the thickness of the cables to the pins on the socket though, as the "sensing" pin maybe the pin that feeds 12v to the fridge and/or battery and may need to supply a fair bit of current. It may need a decent electrician to check the car's installation (don't want any fires!) and modify the caravan wiring as necessary.

I'm with BatchelorDays. Cam or crank position sensor is the usual suspect, but confirm by reading the codes from the engine management system. An altwrnative bet could be not reading the immobiliser chip in the key. Reading codes from the OBD2 port will point you in the right direction.