Accumulator leak malfunction code C1391
09-29-18, 10:41 AM
#2
Intermediate
Before I answer your question, I have a small request for you. Please keep us posted and share with us how you eventually solve the problem. I answered quite a few 1-posting questions. After I took the time to provide my recommendations, the person who posted the question never came back to share if the problem was solved and how it was resolved. Sharing information on this forum will help others who may have the same problem in the future.
-Yes, you can do a lot at home, if you are willing to do it, including fully fixing the problem on your own. Error code C1391 (and C1396) suggests three possible problems: (1) leak in brake hoses between the brake actuator and brake caliper (i.e., not an actuator problem), (2) a bad brake skip control ECU (i.e., again, not an actuator problem), and (3) a bad brake actuator.
-The first step is to check if there is any external leaks on brake hoses. If there is any leak on a brake hose, replace the broken hose and problem is solved.
-If there is no leaks on brake hoses, if you are handy and have Techstream, you can check the brake actuator pressure voltage. A functional brake actuator should have a voltage range of 3.2-4.0V. You do this test with the engine ignition at ON position (but not actually starting the engine). If the brake actuator pressure is not in the normal range, you can do a full brake bleeding with Techstream per factory service procedure and see if the full brake bleeding fix the problem. In some cases, full brake bleeding fixes the problem. If a full bleeding doesn't fix the problem, you will need to replace the brake actuator.
-If your brake actuator has the normal voltage range of 3.2-4.0V, then, your brake skip control ECU is bad and you need to replace it, not the brake actuator.
Hope that this is helpful. Again, please keep us posted about the outcomes.
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The following 4 users liked this post by yyymmm31:
09-29-18, 06:28 PM
#3
Driver School Candidate
Thread Starter
c1391
Subject: Re: Reply to thread 'Accumulator leak malfunction code C1391'
thanks for getting back to me. This is what was going on when the lights
came on. At a red light stopped using the brake hold feature on the
steering wheel. It worked fine until this time. I touched the throttle to
go. within 5 or 6 seconds after leaving the light the brake hold light,
ABS,VSC, Brake malfunction pull over warning and red brake light all come
on. You think the sky is falling. So I had Toyota dealer clear the lights
and he told me at least one of the wheel speed sensors is not talking to
the computer and the cause for all the lights. I left the dealer and the
same lights come back on within 15 minutes. He told me their dealership
did not carry Lexus parts but could order them but still had a problem
programming the new sensor when installed. So a dead end. Went on to see
Craig my friend who has a computer and it spit out the C1391 code.
Changing a wheel sensor looks easy but programming no can do.
Craig recommended at shop that may be able to fix the whole mess and
scheduled for Tuesday next week. We will see what happens. Question do
the new sensors have to be programmed?
Another question. Today my trunk lid will not open, yesterday I could
open only with the dash button, today nothing. It seems I have bought a
host of problems. Love the car. Hope to be driving for a while in my
business. If you know anyone near Knoxville, Tn let me know please and
hopefully before Tuesday.
kindest regards,
Dano3899
thanks for getting back to me. This is what was going on when the lights
came on. At a red light stopped using the brake hold feature on the
steering wheel. It worked fine until this time. I touched the throttle to
go. within 5 or 6 seconds after leaving the light the brake hold light,
ABS,VSC, Brake malfunction pull over warning and red brake light all come
on. You think the sky is falling. So I had Toyota dealer clear the lights
and he told me at least one of the wheel speed sensors is not talking to
the computer and the cause for all the lights. I left the dealer and the
same lights come back on within 15 minutes. He told me their dealership
did not carry Lexus parts but could order them but still had a problem
programming the new sensor when installed. So a dead end. Went on to see
Craig my friend who has a computer and it spit out the C1391 code.
Changing a wheel sensor looks easy but programming no can do.
Craig recommended at shop that may be able to fix the whole mess and
scheduled for Tuesday next week. We will see what happens. Question do
the new sensors have to be programmed?
Another question. Today my trunk lid will not open, yesterday I could
open only with the dash button, today nothing. It seems I have bought a
host of problems. Love the car. Hope to be driving for a while in my
business. If you know anyone near Knoxville, Tn let me know please and
hopefully before Tuesday.
kindest regards,
Dano3899
09-29-18, 06:59 PM
#4
Intermediate
CORRECTION
I thought the Toyota dealer meant the brake pad sensor. After reading your description again, I realized that they said the speed sensor was bad. Discard my posting below. Just replace the bad wheel speed sensor. After replace it, clear the error code and see if it solves the problem. However, it the error code is C1391, it may not be a wheel speed sensor problem.
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If the Toyota dealer talked about a bad brake pad sensor, then it will be an easy fix. Based on your profile, you have a 2007 LS460, which has only two brake pad sensors, one in front and one at back. You don't need to program a brake pad sensor. After replacing it, just clear the error code either by unplugging the negative battery terminal for 10 minutes or preferably using Techstream. Then, everything should be fine. An OE Lexus brake pad sensor could cost you about $100. However, non-OE brake pad sensor can be had for just about $10 (eBay or Rockauto.com). I have also seen that some owners used an "innovative" solution by simply cutting off the sensor cable and clearing the code. If you still get the error code C1391 after you replace the brake pad sensor, you may try the suggestions in my previous posting.
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Last edited by yyymmm31; 09-29-18 at 07:30 PM.
10-02-18, 01:26 PM
#5
Driver School Candidate
Thread Starter
OK, spend most of the day tracking the fix for c1391 and c1210. Lexus is the only place that has bleeding tool after replacing actuator for ABS system. Cost is about 2500 plus labor. So here's the plan. put a switch on the neg. batt. cable to reset the computer at night, drive the car until a less expensive fix and be found.
Any suggestions welcome.
Dano3899
Any suggestions welcome.
Dano3899
10-02-18, 03:48 PM
#7
Intermediate
OK, spend most of the day tracking the fix for c1391 and c1210. Lexus is the only place that has bleeding tool after replacing actuator for ABS system. Cost is about 2500 plus labor. So here's the plan. put a switch on the neg. batt. cable to reset the computer at night, drive the car until a less expensive fix and be found.
Any suggestions welcome.
Dano3899
Any suggestions welcome.
Dano3899
Are you certain it is a bad brake actuator? The only special tool that is needed for replacing the brake actuator and bleeding the brake actuator properly is Techstream, which is the software used by both Lexus and Toyota service centers. A Toyota dealer service center can do the job at a lower cost than a Lexus dealer. It is best to find an indy shop that specialized in repairing Lexus/Toyota cars to do it at a lower cost. A new OE brake actuator costs about $1200. It takes about 2-4 hours to do the work. The basic steps are: 1) use Techstream to release the pressure in the brake booster/actuator assembly, 2) replace the actuator (mechanical work), and 3) use Techstream to bleed the new actuator and the brake system (basically follow the instructions on the Techstream screen step by step, nothing high tech). If you are handy, you can learn to use Techstream and do the work yourself. However, before purchasing a new brake actuator, I suggest that you use Techstream to bleed the existing actuator and the brake system. In some cases, a full bleeding of the actuator and the brake system revived the brake system.
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Last edited by yyymmm31; 10-02-18 at 03:53 PM. Reason: added recommendation
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10-02-18, 05:35 PM
#10
Driver School Candidate
Thread Starter
The tech guy today had meter readings moving around which to him indicated the actuator sensor is bad... O'rellys did not have the DOT5.1 brake fluid. I suppose thats what it takes?
10-02-18, 07:52 PM
#11
Intermediate
No. To bleed LS460 properly, Techstream is needed. It is a must. Whoever said that LS460 bleeding process is the same as any other ABS system doesn't know LS460 brake system. If you or anyone bleeds LS460 without Techstream, you will not have a full bleeding and most likely will end up with more error codes.
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The service manual says that your 2007 LS460 uses DOT3 brake fluid. Any synthetic DOT3 brake fluid is fine. Personally, I have been using Preston DOT3 synthetic brake fluid on my cars and my friends' cars and I am happy with the results. You need 2 32-oz bottles of brake fluid to do a full bleeding on your 2007 LS460. The 32-oz bottle of Preston brake fluid is about $6.38 at Walmart.
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10-03-18, 10:34 PM
#13
Intermediate
You need to use Techstream to do the "replacing actuator" bleeding procedure, not just a regular bleeding procedure. The hope here is that bleeding the actuator will revive your abnormal brake actuator (to save the $1200 for a new actuator). If after bleeding the brake actuator you still get error code C1391, and your actuator's voltage is not in 3.2-4V range, you will most likely need to replace the brake actuator to fix the problem.
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The following users liked this post:
scutch (12-17-23)
10-31-18, 03:24 PM
#15
Driver School Candidate
Thread Starter
the day I scheduled the repair I did the braking test by sliding the car in a field and about 30 minutes of driving all ABS lights went off. WOW, went on the the Lexus dealer and told him what happened and I did not do the 2,200 repair on the ABS, but after leaving the Lexus dealer the lights came back on, so I did the slide again and nothing, lights still on today. Go figure. I will just keep driving until ready to choke up some cash and fix it.