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They certainly could have picked up data from their long term fleet and they probably also have some running 24x7 on the bench too. However there are other reasons for the revisions; cost savings or diversifying the supply chain are common ones.

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Lexus should hold their head in shame. Not that the part failed, as we all know how fantastically well their cars are designed and built but at the diagnosis and quoted repair charge of the dealer.

I have had 2 GS450H's which I loved and i am about to buy my third having been without one for the last 10 months. I am having to buy an older one with higher mileage and no warranty so a bit more risk.

Congratulations on your repair and I hope you do something fantastic with the £3200 you have saved.

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REPAIRED FOR £7 !!!

Hi all,

I have finally repaired my transmission oil pump on my GS450h !!!

After many months of 'trying to find time' to repair it, I finally got the car on a ramp today.

Firstly drained the ATF fluid from the gearbox (approx. 4.5 litres came out). I them removed the exhaust bracket mounted on the gearbox (4 bolts). Then I unbolted the oil pump (4 bolts) from the gearbox and unclipped all the connectors from the oil pump controller and wiring mounts from the chassis and fed the cables back from the engine compartment to the gearbox area. I then checked out continuity of the wiring from the connectors to the pump. All were fine.

Next I removed the pump housing from the motor and inspected the shaft by trying to spin the shaft on the output of the motor. It was seized. I tried moving it with some mole grips and the shaft moved, but grated.

I then took the pump assembly apart to look for brushes (had to drill out 3x M5 screws as they were seized on), only to find that it is a brushless motor with 3 coils, like a stepper motor. I checked out the front shaft bearing and found that it was worn, causing the shaft magnets to grate against the motor coil assembly. Bingo.!!!!! Fault found!!!!

I then visited my local bearing specialist and, hey presto, he had the correct bearing in stock! I also purchased the rear bearing too, just as a matter of course, totalling £14 in parts. They are only little 22mm bearings, and are common parts.

Then I started to reassemble the motor with the new bearings. I had to drill out the 3 M5 screws completely and re-tap the threads to M6 and fit 3x new M6 screws in place.

I then reversed the removal procedure and then filled the gearbox with ATF.

I started the car. The same Hybrid fault came up. So I plugged in my code reader and cleared the P2797 code, and HET PRESTO. NEXT TIME IT WAS STARTED, THE CAR RAN PERFECTLY.

I now had full Hybrid functionality and a fully wrking car.

I am ecstatic. and extremely pleased with myself. Considering Lexus say the only remedy is a new oil pump at the cost of £3240. I have fixed it for £7.

All in all, it took me 5 hours to repair (not including finding a bearing supplier).

Lets hope this is good news for all of us GS450h and LS600 owners (same pump on both cars).

Regards,

Giles.

Hi Giles any chance you could call me on +441628673344.

Not sure where you are in the country.Your post on the bearings is very interesting to me ,as i have been battling with the insurance company ever since i was crashed into.

The Auxillary pump has not worked

Kr Buce

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Hayne, glad you were able to work everything out. I'm still slowly struggling with mine. Your description is very helpful, but i dont understand the mechanics of the tranny that well. I'll see if i can send it to my mechanic to figure out.

Last week my shop took a look and ended up bringing in a lexus mechanic. They say that while the Aux trans pump was plugged in accordingly, the contacts were not actually touching. This caused my aux trans pump to not work, which in turn caused the trans fluid to heat up. When the fluid got to certain temps, it limited my driving slower and slower until I stopped and the fluid cooled. This was to avoid burning through the trans fluid.

They swapped out the plug and the contacts are touching now. The pump is supposedly working, but there must be another issue because the P2797 code is still showing up. My symptoms are closer to yours now, as I can drive fine in engine only (No hybrid), and the car is limited to 70mph. The trans fluid is no longer heating up and causing my car to go into slower versions of limp mode. The above diagnostics and plug change costed me $600 thus far. I'll have them look at the bearing that Hayne describes and hope that is the only other issue.

Thanks

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Thanks Brian. I hope everyone with a GS450h and LS600h can be rest assured that there is a relatively simple low cost fix.

Giles.

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Hi Komain,

If the wiring has been checked, then there is likely to be something else wrong with the pump. It is such a simple design, that the most likely failure point (in my opinion, as I have stripped the pump down fully and inspected this) will be the front bearing.

Before you look at this, have you checked electrical continuity of the pump windings from the loom connector?

The pump has three coiled windings (like a stepper motor), so each of these must be measured. They are fixed coils and is a brushless design (i.e. no moving electrical parts).

Remove the large connector from the Oil Pump Controller (mounted on the left hand side wheel arch under the air box pipe). Get an Ohm-meter, and measure each of the three power wires on this connector, in turn, to ground (battery 0V); i.e. hold the black probe to battery 0V and the red probe to each wire in turn. Each winding will be about 0.5 ohms. It only takes a few minutes to check this, so its well worth while (I wouldn't trust any one else to do it, even if they are supposed to be Lexus experts).

If this is the case, then the pump is mostly likely to be electrically ok. Remove the pump and replace the bearings. I have a basic list of instructions further up this thread.

It is not a difficult job to do either, you just need a ramp for a day. I will find the part numbers of the bearings and post them on here so you can buy them in advance. You will also need 5 litres of Toyota ATF-WS to refill the transmission afterwards.

Good luck with the repair.

Giles.

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Hi Giles,

Although (thankfully) this problem hasn't affected me, I was hoping to get well prepped for if it ever did happen. Your description is fabulous and goes into great detail but as I have never seen a hybrid transmission oil pump, I wondered if you had a picture of the pump off the car so I would know what part to replace?

If this link works, this is what I think it is, but I'm not so sure;

http://thumbs1.ebaystatic.com/d/l225/m/mkw6-_J9wja1rsHroP01p3A.jpg

Thanks,

Mark

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Hi Mark,

No, the pump on your link is a different part. From memory, it looks like a RX400h/450h pump.

I have attached some photos. The pump can be seen from underneath the car when on a ramp. It is located on the lower off-side of the gearbox, so is pretty easy to get to. I had to remove the gearbox mounted exhaust bracket to get to it properly before removal.

As you can see, it is a well engineered, simple part with one moving part; the impeller shaft. The three coils are fixed, therefore there are no brushes to wear out and the shaft has the magnets mounted on it. There really is not much to go wrong with it. It's just a shame that Lexus made a poor choice of bearing specification.

The two bearings can be seen in the photos. One is located under the circuit board (this is the shaft position sensor board) and the other is at the bottom of the motor housing (can also be seen mounted on the end of the shaft in he photo.

Hope it makes sense.

Giles.

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post-48671-0-23316700-1427580617_thumb.j

post-48671-0-61976000-1427580622_thumb.j

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Thanks Giles, those pictures are perfect. You're right about the picture I supplied being from an RX, I assumed they were the same part as the GS.

I had visions of buying a used hybrid transmission oil pump, reconditioning it and having it ready to swap straight over should it go wrong however they look rare as hen's teeth. I think I will just chance it instead. Thanks again for the pictures.

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Mark, I spent months looking for a used broken pump, nut it appears they are just discarded. If it does fail, it only takes an hour or so to replace the bearings.

The best preparation would be to buy the bearings ready for if it does fail. I will have a look for the receipt from the bearing place for part numbers and dimensions.

Giles.

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Awesome photos Giles. I'm hoping you can get a copy of the receipt to show the bearing part number.

I actually ended up buying a used transmission a few months ago since my original symptoms were a bit different from yours. My shop checked all of the connections already to ensure electrical continuity. I'm waiting for the weather to warm up before I take the spare transmission pump apart. Will let you know how it goes in a few weeks when i get some time. Thanks again for all your help.

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You're welcome Komain. I will dig out the receipt this weekend. The bearings are a standard size that most bearing manufacturers will be able to supply, so I will post the dimensions on here too (if I can find my verniers!).

Good luck with repairing your spare pump. If you need any help, just PM me your number and we can have a chat.

Cheers.

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I have found the receipt for the Hybrid Pump bearings.

Not sure if the part numbers would make sense, so I have measured the bearings with vernier callipers so the correct parts can be ordered.

I bought mine from Brammer UK Ltd, in Hereford (01432 276630). The part numbers are 61900-2Z and 608-2Z. They were in stock at the time.

The dimensions for the front bearing are 22mm OD, 10mm ID, 6mm width.

The dimensions for the rear bearing are 22mm OD, 8mm ID, 7mm width.

Giles.

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I have the same problem as you your self Hayne.

Check Hybrid System came up on dash board along with the VSC light.

The car works on combustion engine alone with no input from the Hybrid system.

After driving for 40 miles, I switched the car off. When I restarted it the VSC light was off.

Hybrid light is still on.

The Aux battery has been checked. Voltage is 12.7v.

I have ordered a code reader. If I get the same code as yourself then the fault will be narrowed down.

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Sounds like similar symptoms that I experienced.

Once you have read the codes, that should head us in the right direction.

If it is the pump, at least its a relatively easy and cheap repair (as long as you don't visit a Lexus dealer!!).

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Sounds like similar symptoms that I experienced.

Once you have read the codes, that should head us in the right direction.

If it is the pump, at least its a relatively easy and cheap repair (as long as you don't visit a Lexus dealer!!).

I disconnected the 12v battery for a few seconds hoping that it would reset the system.

Lo and behold, it did!!!

Hybrid system is working fine now.

There is a ticking noise coming from the middle of the car. I am guessing it is the oil pump but will have to wait until code reader arrives so I can diagnose it.

When I select reverse, a warning comes up on the sat nav screen saying "System Initializing".

Have not driven the car since the reset.

Whilst the Hybrid system was offline I drove the car for 120 miles. Horrendous fuel economy. 23-25 urban, normally it's 30-32. and combined came to 27, normally it is anywhere between 32 and 40.

I will keep you all posted. Just waiting for my diagnostic machine to arrive. Bank holidays!

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Exactly the same fuel economy figures as I had!

Once the car detects that the pump shaft won't rotate, it will always show the fault on the dash until reset. Sometimes, the worn bearing will give a bit, allowing the pump shaft to rotate, therefore clearing the fault.

If it is the pump bearing, this WILL happen again and will become worse over time, so be aware that you will grind to a halt again, potentially in an unsafe situation next time. If it were me, I would unplug the pump loom from the pump motor controller (mounted to the chassis under the air box) and drive it in ICE only mode until you confirm the fault.

One guy on this forum (Bruce, with an LS600h) saw my post and went through the same procedure, but found that the bearing had seized completely, but was still rotating within the motor housing, with the bearing wearing away at the housing. He needed a slightly larger bearing to fit in the same hole. It is a torquey little 3-phase motor, so allowing it to run after the fault has been detected may be causing you more problems when you come to repair it.

Giles.

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Exactly the same fuel economy figures as I had!

Once the car detects that the pump shaft won't rotate, it will always show the fault on the dash until reset. Sometimes, the worn bearing will give a bit, allowing the pump shaft to rotate, therefore clearing the fault.

If it is the pump bearing, this WILL happen again and will become worse over time, so be aware that you will grind to a halt again, potentially in an unsafe situation next time. If it were me, I would unplug the pump loom from the pump motor controller (mounted to the chassis under the air box) and drive it in ICE only mode until you confirm the fault.

One guy on this forum (Bruce, with an LS600h) saw my post and went through the same procedure, but found that the bearing had seized completely, but was still rotating within the motor housing, with the bearing wearing away at the housing. He needed a slightly larger bearing to fit in the same hole. It is a torquey little 3-phase motor, so allowing it to run after the fault has been detected may be causing you more problems when you come to repair it.

Giles.

I won't be driving the car until I have diagnosed the fault. Better safe than sorry.

Bearings were ordered on Saturday so they should arrive this week sometime. I will get a local mechanic to fit the bearing. I am guessing it should take him 3-5 hours max.

I would rather pay £200 to an independent garage than £3500 to Lexus.

Saved a fortune by the looks of it. Also found some one who can recondition the batteries for £800 should the pack ever fail.

Hybrid Battery Solutions

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Ran a diagnostic check on the car yesterday. Came up with Hybrid battery failure. It was a Generic P0 code. Didn't write it down. I cleared the code and the car seems to be fine. Going to leave it for a few days and see if the code re-appears.

Due to the code being generic, I am not entirely convinced that battery has failed. I will need to examine it further with a more detailed diagnostic tool.

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Error code 3027. Battery module 17 needs replaced.

Fan for battery coolant system runs at high speeds.

On display the battery is charging and de-charging within a few minutes even when the car is stationery.

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New member moved across from Prius Chat having just changed from a Prius to a GS450H.

 Thanks Giles for the information on the pump motor bearings. I live in north Herefordshire, and would be happy to buy you a pint on behalf of the other members.

In time I hope to contribute much to this forum as I hope I did on Prius Chat. I have an electronics background that is useful working on hybrid systems. I also have Techstream so am able to read all fault codes, and am happy to read codes for anyone able to get to me.

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Edited to replace step by step write up with a blog post:

Many thanks to Hayne, without whom I would have bunged this into a dealer and probably spent 7-800 pounds on a pump or £3k on a transmission. If you have the P2797 code and suspect the pump bearings it's worth a go.

Armed with some car lifting kit, new transmission oil and bearings for both ends of the pump I carried out the pump repair over the weekend. Also used basic tools, spanners, oil drain tray and a pump for squirting the new oil in. Allow a full day but if you're very mechanically minded with a good set of tools you might half it. Photos and steps attached: 

http://carlthomas66.blogspot.co.uk/2016/03/lexus-gs450h-transmission-oil-pump.html

Took me twice the time Hayne did but I didn't have a ramp. So allow a day at least depending on access, tools and mechanical skill. Test drive it. Do a lot of gentle battery only driving to make sure the pump gets a good run and look out for dash warnings. Then a final check with the Mini VCI if you have it and hopefully no more P2797. Take it for a long run. I blasted mine up to Stansted and back to pick up the girlfriend! Brave I know!

Then celebrate with a beer. After you park up the car! I did!

Good Luck!

 

 

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Well Carl, I'm very impressed that you did this on your driveway without a ramp!!

Very commendable. And without removing the wiring loom! This is a great example of proper DIY.

I bet you are well chuffed with yourself! I know I was when I fixed mine. You are the 4th person to use my post to fix your car.

And, it's good to see such great step-by-step instructions. Should help others in the future.

You said that Lexus charge 7-800 for a pump; when I asked them for a new pump they wanted £3240 just for the pump (not including the gearbox). When Bruce did the same on his LS600h, Lexus quoted £8k for a new gearbox, so it's probably not much less for the 450h.

Again, well done Carl. I bet that beer tasted just fine!

 

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Carl, what's the HV battery conditioner you used? Sounds interesting...

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Cheers for the comments. But you were the pioneer! 

I bought the GS a couple of months ago. It had been stood a few months. After driving it a short distance it died on me. Then after restarting it did the same again. I limped it to the Lexus dealer for a hybrid health check. They listed the fault codes for me. And the estimated prices for the repairs which came to more than I paid for the car!

I searched around and all roads pointed to Richard at hybrid battery solutions in Northampton. I left the car with him and he pointed out that he could repair and recondition the battery for me but the gearbox oil pump issue meant that the battery management wouldn't be exercising the battery correctly and the guarantee would be invalid. It was probably a partially seized pump bearing and being stood so long that had killed the battery in the first place.

Whilst Richard did the work on the battery he gave me the additional option to install a port to attach a battery conditioner unit. I thought that I plan to keep the car quite a few years and it might save me a couple of trips to Northampton. 

You can attach the conditioner and plug it into the mains overnight. Or for up to 39 hours. Or leave it on a timer one hour a day if you go on holiday. I'm hopeful that now the oil pump is fully working I won't need the conditioner too much. But it's good to know that I have it.

Have a look at Richards site on the web or his eBay page. There should be more info there. And I think he's subscribed to this thread and will probably come along and correct some of my info! He's a very knowledgeable guy.

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