Transmission oil motor pump assembly
 

Hello everyone. I have been having some issues with my 08 450h. I will give you all some background on the issue. My car has just over 118,000 miles on it. About a week ago my check hybrid system warning came on while I was at work. I called a dealer and was told to drop it off for diagnostics. That whole day I drove it and according to the display screen, my hybrid batteries charged and discharged as usual and the car felt fine. Before I could take it to the dealer, the light went off so they told me to wait until I got a warning again. Two days later, the light came back on while I was at a red light and the car shut off. The car had literally only been running for less than 5 minutes before this all happened. I put the car in park and started the car right back up again and it started just fine, but the warning lights remained. I took the car to the dealer and left it over the weekend. The dealer checked the car on Monday and told me that they got several codes and they felt that not all of them would possibly be bad all at once so they decided to clear the codes and have me drive it until the lights came back on to see if they could get an accurate code. I drove the car for about a day and a half and about 120 miles or so and the light came back on while I was parked at work (this morning). I called the dealer and informed them and took it back to the dealer. I got a call later to come past the dealership(this evening). They informed me that indeed it was only sending out one code now and that that code was for the transmission oil motor pump and the tech said that he inspected it and found that the part was bad and that all of the other components looked good. They quoted me $3900+ to repair this issue. I wanted to see if anyone else has had this part fail, and/or if anyone has any insight on what this part is exactly? The service guy told me that I could fix it or that I could sell it to one of the number of mechanics there that were interested in buying my vehicle. I really like the vehicle and have gotten really comfortable with it in this short period of time I have had it (3 months/6,000mi). Not sure if I should just sell it and cut my losses or shell out the money to fix it. I would really want to find a way to fix it for much less. Any help would be greatly appreciated.

Known issue. The pump's DC motor bearings have seized - one or both. Fixable for a lot less :P

Read this:
https://www.clublexus.com/forums/hyb...8-gs-450h.html
and this:
https://www.lexusownersclub.co.uk/fo...loss-of-power/
and this:
http://carlthomas66.blogspot.com/201...-oil-pump.html

Note that the uk lexus club thread and the blogspot posting are for right hand drive cars, you'll have to disconnect transmission oil cooler lines (metal ones that attach to the transmission, not just the hoses unfortunately) on yours to get to the pump... unless the EU-spec LHD model somehow differs to the US spec.

I'd also change the ATF and oil strainer (well, the filter :P) while you're doing this.

The part on the schematics:
https://lexus-europe.epc-data.com/gs...is/3901/35300/
Multiple part numbers depending on years, I don't know if different years are incompatible... I'd wager it's just upgrades (better bearings? :P). I'd just pull the pump and do the transmission oil at the same time.

As for the pump itself - from what I've seen (i.e. recorded with techstream out of curiosity), it runs primarily at lower speeds and when stationary, I guess it's circulating the oil while the crankshaft driven pump (I assume there is one, the ls600h has one, according to the oak ridge national lab teardown) doesn't work. It also spins when MG2 shifts between high and low gears.

Good luck!

Thanks for the reply. I will look into this. Will any mechanic be able to do this?

I started reading the first link and noticed that the OP stated ending up in limp mode. I see that a lot on different threads and that is where my car is different. My car never feels any different. It runs basically normal outside of the 2 or 3 times it shut off. Also all of the times it did it was idle. Once at a traffic light, once parked in a driveway, and the last at the dealer switching my stuff from my car to a loaner.

Can you scan the car and post the exact codes that are output? It's a bit of a guesswork otherwise.

In addition, if you have access to techstream with a decent interface (mongoose pro(pretty much OEM), tactrix openport, vxdiag vcx nano, some others), you can check the DTC's freeze frame data, and the pump's operation. The "active test" (or utility, can't get to the car right now) menu in the hybrid control section has a "force pump to run at 500/1000rpm for 30 seconds" option - you can set that and watch the requested/actual RPMs in the live data view. If the pump doesn't spin at all, this should diagnose it quickly.

EDIT:
One more thing about the shutdown at idle (well, "idle" - most likely engine isn't running) - from what I've seen (mentioned this in my first post), that's when the pump runs the most, I'm guessing due to the shutdown of the crankshaft-driven transmission pump. I can record some data on my way home today if you don't think that's the case.

EDIT 2:
Forgot to mention - might be the motor pump controller ECU as well (located somewhere in the engine bay, check the schematics), or the harness to the pump (which can't be easily separated from the pump itself - it's not a connector)… at least that was mentioned in some (or all?) of the threads that I linked.

Better late than never. Took a... scenic route, 50 minutes drive total (usual is 15):

https://cimg2.ibsrv.net/gimg/www.clu...3552421387.png

Would this be included if I just replace the whole tranny?

It's an external pump, most of the 2nd hand transmissions I've seen come without it. They're usually sold separately.

Ok thanks! Is this the right part:
https://parts.lexus.com/p/Lexus_2008_GS-450h/PUMP-ASSEMBLY---OIL-WITH-MOTOR/63066821/3530030032.html

I call l the parts department at the dealer and they quoted me $2547 for the part, so it is cheaper on that site.

That, and all the parts that it supersedes. I'd get the highest number - the later revisions should be better.

Again, consider doing some data logging to get a better feel of what's going on. Also consider doing the bearings instead of changing out the whole unit. You'll have to drain ATF from the transmission and remove the wire harness regardless.

I did not have to remove harness. If i can go back, i wish i got it up on a 2post lift. Also not a mechanic but good with tools. My subcode was 865

Correct, for swapping bearings you don't need to remove the harness, but getting the pump on a table instead of hanging on the cables gives you many more options. A 2post lift will still be massively better :)

2013 Gs 450h
 

https://cimg1.ibsrv.net/gimg/www.clu...f16668c10.jpeg
Hi everyone, is anyone know what’s can be the problem. I had rear all the information more about 3-rd generation had fail with Auxiliary transmission pump . Soo my car is driving fine is just takes few second until starts the engine and is running all the time plus engine light is on and check hybrid system. Could anyone help me please ? Thanks

I have the feeling that you have the right solution