Hayne

Hi John, Yes, I'm still running it without Hybrid functionality. It runs absolutely fine, just with less economy. I haven't had much chance to fix it lately, but my findings are as follows; Read fault code. Checked all Hybrid fuses ok. Removed battery and reapplied to see if fault resets - it returned straight away. Put the car on a ramp to check ATF level - all is ok. While on the ramp, I checked the power to the pump - 14 volts present, so ok. I have come to the conclusion that the pump is at fault, not the pump controller or wiring. The cheapest price for a new pump is about £900 online, so I'm not prepared to pay that until there is no other option. On inspecting the pump, the electric motor housing appears to have got hot, which points towards an electrical fault with the pump. The brushes could be worn, or the motor needs rewinding. My next step is to remove the pump and check the brushes and windings and repair it. I just want to make sure I can remove the electric motor without the ATF draining out so I can still use the car, otherwise it will be off the road for a few days. I have contacted a motor re-winding shop who say they are likely to be able to rewind the motor for me. I hate this modern throw-away society. No one wants to repair anything anymore. I my opinion, everything is repairable!!! I'd rather repair the pump for £100 than spend £900 on a new one (well, who wouldn't). I will post again when I have an update. Regards, Giles.

I've only just got round to checking some electrical stuff and have checked fuses and relays relating to the Hybrid system and Oil Pump, but I can't find the oil pump fuse. It clearly states the location of this fuse in the left bank of fuses within the fuse box on the engine bay fuse box lid, but when I open it, there is no left hand bank of fuses where expected. There is a connector loom block which pulls out of the fuse box but still no fuses underneath. All the other normal fuses are where expected and labelled accordingly on the right hand side of the fuse box. Does anyone know how to locate it? Under the connector block, there looks like a silver colour bus bar under a clear plastic cover, but that doesn't look like fuses to me. Any ideas? any thanks.

That is great Colin. I will purchase an hours access and look up the info. I didn't realise this site existed. Thanks again. Giles.

Valid point Ganesh, but the mechanical transmission pump driven from the engine is working fine. The auxiliary pump only operates when there is no engine power (i.e. in Hybrid mode). As the hybrid system is currently disabled, the auxiliary pump is not required, therefore i believe that it wont do any damage.

More of an observation than a question, for those who may be interested; Since my hybrid transmission pump packed up, I'm now running on just the 3.5 petrol engine with no hybrid system. I normally get an average of 33mpg with the hybrid system working, but without the hybrid, on the same journeys i am getting 28mpg. Not a huge difference! (not as much fun running at 50bhp less though).

Does anyone know where the auxiliary transmission pump is located and what it looks like? Also, are there any wiring diagrams out there for the GS450h? Thanks.

Colin, Thank you for your fast response. I will disconnect the battery tomorrow and report back. I will check the fluid levels too. It doesn't sound too common, but I found a thread where someone was quoted £3600+vat for a pump form Lexus !!! That sounds ridiculous. If it is the pump, I have just had a quote for about £300 for a used one, and a thread tells me it is 3 to 4 hours labour to fit. Of course, I will diagnose before buying it, but I am very reluctant to use a dealer for diagnosis, as they are notorious for just replacing parts instead of carrying out a professional diagnosis, as you suggest (in my experience, main dealers are only useful if your car has warranty). Still, the car drives perfect, it will just be higher on fuel consumption until I repair it. Thanks again. Regards, Giles.

Hi, I was driving home today and some warning lights came on saying there was a hybrid fault. I have just read the OBD fault code and it came up with 1 code P2797. I googled it and it says 'Auxillary Transmission Fluid Pump Performance'. Has anyone had this fault or heard of it please? I restarted the car and it drives in petrol mode only. The gearbox and engine seem to be running fine, just no hybrid function. Any help is much appreciated. Regards, Hayne.

Hi, thanks for the info, but tried it and, no, bonnet and door open don't keep the engine running. But, putting the cabin temperature on high does seem to work for a while, which is good enough for me. Thanks for all the replies guys.

Hi Tony, I am surprised there is no emission test for Hybrids. Still, nice that it will never fails on emissions!! It just doesn't make sense that there is no way that the engine can be forced on when it is in for repair. Lexus must be able to do this even if it is a hidden function. I will give Lexus a call and see if they can enlighten me. Regards, GIles.

Hi, I'm afraid not. Sports modes still keep the engine off when no power is required. As you say. there must be a better way than draining the batteries. Maybe I'll try holding the power button down for a few seconds and see if that does it. Thanks for the reply though!

Hi, I was showing my friend my GS450h today and he asked to hear the engine. Of course, it was already warm and just stayed off when the power button was pressed, due to the Hybrid system. The question is: how do I force the engine to run when stationary? Surly there must be a way to do this when carrying out maintenance/fault finding or emissions testing during an MoT. Anyone any ideas? Thanks. Giles.

Many thanks for your advice, Tony and Kevin. I went out and bought one this weekend. It's an immaculate GS450h SE on a '57 plate, black with black interior, one owner from new, full Lexus history.. It's absolutely beautiful and drives perfect. There is not a thing wrong with it (I'm not used to that with owning German cars!!!). I bought it discounted with a tyre pressure monitor fault, which the seller couldn't fix. Got it home and read the manual and its all reset fine now! (just needed initialising). I travelled home on the motorway with the cruise at 80mph and got 37mpg, which I am pretty impressed with. Went on a country road journey on very light throttle and got 42mpg, which is incredible!! What a car. And, of course had to try the Hybrid PWR button. Definitely the fastest car I have ever owned (much quicker than my recent BMW 745i). Thanks again. Regards, Giles.

Hi, I am new to the forum and just wanted to ask a few questions about the GS450h. I am interested in buying a GS450h around a 2007 model, but would like to know how reliable they are. I have owned several high end cars over recent years, such as a BMW 535i, Audi A8, BMW 745i, etc, but I am fed up with cars developing faults or breaking down. I have had gearbox issues on some cars, two of which had to have reconditioned at huge costs. I have read about the GS450h and all reviews say they are outstanding cars which just don't break down. Is this true? Are the CVT gearboxes reliable? how many miles do they usually last before replaced/reconditioning? What are the weak points (every car has them from experience)? As it is a hybrid, is there anything I need to look out for? Does this make them more unreliable than the GS300 or GS430, for example? Is the fuel economy as good as claimed? My hilly mixed driving route to work sounds ideal for a hybrid. On the motorway, does the electric power have any affect? I can't imagine it would as at continuous speeds, I would expect that the electric motor will be redundant. Will it just be the economy of a 3.5 litre petrol on the motorway? Also, how does the driving experience compare to say, a 5 series BMW? (I like the way BMWs drive!!). Sorry for all the questions, but I just want to make sure I am buying the right car. Many thanks in advance. Regards, Hayne