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The decision depends on the affordability. Here in the States, a brand new LS460 brake actuator at my local Lexus dealer is priced at $1,870 (part number 44050-50170, which is even not the latest model number), and on eBay some Lexus suppliers are selling a brand new but older model of brake actuator for about $1,000 (part number 44050-50110). Also on eBay, used and refurbished LS460 actuators are priced between $400-$700. If you know the history of the used actuator (newer LS460 with lower mileage) and the price is substantially lower than new brake actuators, then go for it. Of course, if there isn't significant difference in prices, you should go for a brand new brake actuator.
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So I did bled the brake system at the service station, and there was an air in the rear circuit, so my rear brakes were not actually working, technicians were able to rotate rear wheels while brake pedal was fully depressed. It solved the issue for some hours, so on the way home I've got all the warnings except "Brake Malfunction" again)
And now 1 day after service I cannot clear the errors anymore, even by disconnecting the battery.
So I believe my ABS actuator needs to be replaced.
And here is another question: I found brand new actuator, part number 44510-50090 for 1500$ with 1 year warranty from manufacturer. Is it the latest one?
Can also opt for the same, taken from 2017 LS600 with 12.5k miles for 1000$, but i'm afraid of conditions of storage, if some moisture or dust came inside, than probably it will not serve as long, or as good as new.

 

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From your description of the problem, it seems to me that you have a leak somewhere in your brake system. The reason is that your technician fixed the problem (bled the air out of the your rear brakes) but the problem came back after a while (most likely from a leak somewhere in the brake system). Once again, it is rare for a brand new brake actuator to be bad out of box, and it is even more rare for two brand new brake actuators to be bad out of box. So, I'd check the brake hoses and joints for leaks and fix the brake hardware leak before purchasing a 3rd new brake actuator. As for the brake actuator part number, here is what Club Lexus members reported: Brake Actuator part number: Latest 04003-45450 (older 44050-50170, 44050-50130). They all work, but the latest part number is supposed to fix the brake noise problems and is believed to have a longer service life. Brake part number 44510-50090 will also work, but it is an older part that has the problems reported by members of the forum, such as noises and shorter lifespan. If you know the history of the used brake actuator (low mileage and no existing problem), you could save some money to install a used brake actuator. Despite the reported brake actuator problems, most brake actuators actually last as long as the lifespan of the car. BTW, disconnecting the battery doesn't not clear brake trouble codes. You need to use Techstream or similar tools to clear the brake trouble codes.
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Thanks for reply!
I've probably described something wrong, the actuator I'm using now is the original one from 2007 and has never been replaced.
Regarding leak somewhere, that were my thoughts as well, will try another service station to do a whole system check.
As for the clearing errors, disconnecting the battery did help me before, just like the simple stop/start engine, but this time all the lights stay on the dash.
And much thanks for mentioning part numbers)

 

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Got it. You have been trouble-shooting the original brake actuator and haven't replaced it yet. In this case, with the trouble codes C1246 and C1364 and considering the age of the original brake actuator, and also since you have performed the "brake actuator replaced" bleeding procedure without curing the problem, it is most likely that the problem is with the brake actuator. To cut down the cost, you could consider the low-mileage used brake actuator from a 2017 LS600 instead of a new one.
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Sorry for late response
I'm not quite sure that brake bleeding was performed using "Actuator has been replaced" function, since I was not present there at the time and basically nobody would allow me to stay there and stare at technician.
I've been running car for some time now, C1246 error still comes frequently (like every other ride)
But today I've got a new code C1365 and buzzer sounded all the time
Since I now have Techstream and cable, I tried to clear the code, but couldn't. It just stays there along with the C1246 and C1364
Does it mean that actuator is finally dead? or I should I try to perform brake bleeding by myself, following TSB?

 

Hi hardtopte7,
Just curious about step 6. If the accumulator connectors are disconnected, with the ignition ON does the accumulator run ?. Please clarify
Thanks,

 

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If you are not certain that the technician actually performed the "Actuator has been removed" bleeding procedure and if you have Techstream, you may do the procedure yourself. It will confirm if you have a bad actuator or not. Before performing the bleeding procedure, make sure that your car's battery is fully charged and preferably connect a good charger to your car's battery. Performing the "Actuator has been removed" brake bleeding consumes a lot of battery power. A dead battery in the middle of brake bleeding will trigger trouble codes and complicate the situation.
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Hi, acican. Hardtopte7 was basically saying that he should have begun the bleeding procedure by going directly to Page 19 of the instruction and performed the bleeding procedure by following the instruction on Techstream screens, foregoing the manual bleeding steps prior to Page 19. Since you have already successfully bled your front brakes manually, you may try this way too. That is, begin your bleeding procedure by going directly to ABS/VSC/TRAC => Air Bleeding => Actuator has been removed, then follow the screen instruction to dry-run the two front brakes and then begin to bleed RR/Actuator, and then RL brake, and follow the instruction on the screen to zero down four times, and reset memory and do the linear calibration to complete the bleeding procedure.
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So I've performed a brake bleeding as per tutorial using "Actuator has been removed" function. Everything went smooth except last step bleeding RL contour.
While I held a pedal depressed, and my fellow opened a bleeding pot, compressor started running and there was a knocking noise coming from actuator.
However procedure went well, all calibrations were ok and DTC cleared.
But after test ride all codes went back, C1246 C1364 and now C1365, stating there is a trouble with accumulator pressure sensor.
So I checked Data via Techstream and found out that accmulator pressure sensor voltage is 4.8V, far beyond 4.0V limit. But at the same time, compressor keeps on building up the pressure, i.e. starting by itself every 10sec or so. And that's not clear to me. I undertsand if the pressure was low, so it tried to buid it up again, but what is the reason to pump fluid if it's already excessive?
Anyway, other thing I decided to do, is to disconnect the actuator and ECU harnesses to check resistance (found some tutorial for electronically controlled brakes diagnostics on Prius)
Then I discovered that ECU harness is different from that used on Prius, and just reconnected them back and voile, brakes feel good again.
So, can this DTCs be caused by a faulty harness connections?
I did test ride with Techstream connected and observed that from time to time there is a difference beetween Master Cylinder pressure sensor 1 and 2, and also benwee W/C sensors, and I think that's what triggers C1246 and C1364 codes. From time to time however I still have this barking noise from actuator, when coming to stop and starting from standstill. Here is a screenshot with Techstream Data List.

 

Hi vvdos,
When you perform bleeding with " Actuator has been remove" procedure, do you recall that after manual bleeding the FR,FL ,ignition OFF and put back the pump connector does the pump comes ON when you turn the ignition ON. For me I can't pass this step since the accumulator sensor voltage must be less than ~ 0.5 volts in order to proceed to the next step. If you don't mind can you provide me all the steps you performed the bleeding.

Thank you,

 

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Glad that you performed the "Actuator has been removed" brake bleeding procedure successfully, but sorry to hear that it only temporarily solved the problem. The possible causes for all three trouble codes C1246, C1364 and C1365 are faulty actuator assembly, faulty skip control ECU, or bad electric wire connections to and from the actuator assembly. Your observation of accumulator voltage is outside the normal range of 4.7V - 5.3V confirms that the issue is within the actuator/pump assembly. Since the "Actuator has been removed" bleeding procedure didn't revive your actuator, at this point, I'd be more leaning towards that you brake actuator is giving up. Can C1246, C1364 and C1365 be caused by faculty harness connection? Yes, they could be, but given your description of the problem, I'd think that your brake actuator has more to do with the trouble codes than faulty wire connections. However, I am no Lexus certified technician and I am sharing with you what I'd do at this point if it were my own car, but I can be wrong here.
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Hi, akican!
I strictly followed the instructions given by yyymmm31 in post #7 https://www.clublexus.com/forums/ls-...l#post10762895
after connecting pump motor relays it did not start, so pressure of my accumulator remained below 0.5V

 

Thanks anyway
I'm also thinking it is an actuator itself, but just trying to eliminate all other possible causes since I cannot find newest actuator model on the websites your mentioned in PM
and much thanks for starting this thread, it's really helpfull)

 

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Please keep us posted how you eventually solve the problem.
Best regards.
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