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07-15-2015, 12:58 PM
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#1
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Senior Member
Name: Gordon
Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
North Carolina
Posts: 5,155
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Tug throttle cut off when trailer brakes activated manually
I have installed a Tekonsha P3 in a 2015 Toyota Sienna and noticed that if the vehicle’s throttle is activated (gas pedal pressed) and the manual control on the P3 is activated at the same time, then a warning is displayed in the dash and the throttle is cut off. The van then coasts until the manual control on the P3 is released. This is with no trailer even connected and I assume it would be the same with a trailer. The same thing happens if I press both the brake pedal and gas pedal at the same time, even with the P3 disconnected altogether. I guess this is one of the design changes that Toyota made after all the inadvertent acceleration lawsuits.
My question: is this normal operation for the brake controller? Would it even present a problem?
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07-15-2015, 03:35 PM
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#2
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Senior Member
Trailer: 2002 19 ft Scamp 19 ft 5th Wheel
Posts: 3,640
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Does not do that on our Silverado. Ask Toyota.
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07-15-2015, 03:57 PM
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#3
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Senior Member
Name: Gordon
Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
North Carolina
Posts: 5,155
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Quote:
Originally Posted by Darwin Maring
... Ask Toyota.
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Please don't suggest that. The last time I asked Toyota a question about towing equipment I got this response:
Thank you for contacting Toyota Motor Sales, U.S.A., Inc.
We apologize as we do not recommend or assist with modifying our vehicles from the original factory specifications.
Toyota's warranty covers repairs and adjustments needed to correct defects in materials or workmanship of any part supplied by Toyota.
Modifications to your vehicle could affect the performance, safety or durability, and may violate government regulations. Non-Genuine Toyota Parts, or any damage or failures resulting from their use, are not covered by any Toyota warranty.
We are sorry; we do not offer a tow wiring harness, for your vehicle. Regrettably, we do not have any recommendations to a supplier or source that may.
Your email has been documented at our National Headquarters. If we can be of further assistance, please feel free to contact us.
Sincerely
Greg S.
Toyota Customer Experience Center
As you can see.. they are NO HELP AT ALL.
I will ask Tekonsh / Cequent Performance Products however. I did contact them before and they actually helped me.
BTW, does your vehicle do as I have described with the gas and brake both pressed at the same time?
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07-15-2015, 04:19 PM
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#4
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Member
Name: John
Trailer: Casita
California
Posts: 52
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Mine does not..... P3 in a Nisaan Murano
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07-15-2015, 04:27 PM
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#5
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Senior Member
Name: Gordon
Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
North Carolina
Posts: 5,155
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I guess what I need to know is:
Does this happen in a Toyota or other make vehicle that has the "safety feature" that cuts off the throttle when you hit the brake and gas at the same time?
If your vehicle does NOT have this "feature" then it seems the brake controller will not cut off the throttle, just as hitting the brake and gas pedals simultaneously will not either.
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07-15-2015, 04:32 PM
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#6
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Senior Member
Trailer: Class A Motorhome
Posts: 7,912
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Me thinks that you need to move up the line at Toyota for some help, otherwise they may pretend to not know you if something should d happen and the problem you are describing is certainly making your vehicle unsafe to drive. For example, if you encounter severe trailer sway you may want to be able to apply trailer brakes while at the same time maintaining positive throttle
This Brochure and several Toyota press releases describe both an "Up to 3500 lb towing capacity" as well as the availability of a towing harness:
http://www.toyota.com/sienna/ebrochure/
In as much as many states require trailer brakes at well below 3500 lbs (1500 in California) I it would seem that they (meaning Toyota) has a problem if there is no way to connect a brake controller into their fly-by-wire throttle control system.
Basically I doubt if they want to be sued for selling a vehicle that can't legally tow what they claim it can tow. Put the ball back in their court.
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07-15-2015, 06:49 PM
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#7
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Senior Member
Trailer: 2002 19 ft Scamp 19 ft 5th Wheel
Posts: 3,640
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Bob Miller has the answer. Send a Certified letter to the CEO of the company outlining the situation. Be sure to cc (Carbon Copy) one to the Highway Traffic Safety department so Toyota knows the letter must be answered. The CEO more than likely will never see it because they have people to handle these things but it will get their attention.
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07-16-2015, 06:22 AM
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#8
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Senior Member
Name: Gordon
Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
North Carolina
Posts: 5,155
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The following is the reply to my query from Tekonsh / Cequent (a company that, unlike Toyota, believes in supporting their customers).
Thank you for contacting Tech Support. When you apply the manual lever on the P3 it turns on the brake lights of the vehicle, which makes the computer think you are applying the brake pedal. This is normal operation. If I can be anymore help, please let me know.
Best Regards,
Dan
Danny Dunn
Technical Service Coordinator
Cequent Americas (Electrical Division)
101 Spires Parkway
Tekonsha, MI. 49092
(888) 785-5832
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07-16-2015, 06:36 AM
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#9
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Senior Member
Trailer: Class A Motorhome
Posts: 7,912
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I think that provides an answer as to why it happens, but is that a good idea when towing???? I think that Toyota needs to provide a method to over-ride this feature if they are going to advertise a 3500 lb towing capacity.
No doubt they will as soon as someone pulling a trailer gets into an accident when they unexpectedly loose engine power when manually applying trailer brakes.
But wait.... maybe that towing limit only applies to trailers with surge brakes, such as boat trailers...LOL
I would expect that update within 30 days after the first lawsuit is filed.
Again, write to Toyota and copy to the NHTSA.
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07-16-2015, 07:21 AM
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#10
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Senior Member
Name: Gordon
Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
North Carolina
Posts: 5,155
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Quote:
Originally Posted by Bob Miller
I think that provides an answer as to why it happens, but is that a good idea when towing????
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That is now the question for this thread.
Do you need to keep throttle on when applying trailer brakes to stop sway? Is it just as effective to release throttle while lightly applying trailer brakes, and after sway is under control, then resume throttle ?
Termed, Toyota smart stop technology, this feature can be disabled on some other makes apparently, but I do not find a way to disable it on a Toyota (not surprising since they were hit so hard for what was mostly driver error).
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07-16-2015, 07:51 AM
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#11
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Senior Member
Trailer: Casita Spirit Deluxe 2003 16 ft
Posts: 1,899
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I think I would find myself in this situation fairly often (manual trailer brake apply while tow throttle applied). After first hooking up each trip I confirm the controller setting by briefly using the manual control and after crossing a puddle I might drag the brakes briefly while still more or less maintaining speed. Its not a deal-breaker since I could test & drag with my foot off the throttle, but I don't think I like that particular Toyota "feature".
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Quando omni flunkus, moritati.
Also,
I'm a man, but I can change, if I have to, I guess.
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07-16-2015, 08:21 AM
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#12
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Senior Member
Trailer: Class A Motorhome
Posts: 7,912
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Sway Control
Quote:
Originally Posted by gordon2
That is now the question for this thread.
Do you need to keep throttle on when applying trailer brakes to stop sway? Is it just as effective to release throttle while lightly applying trailer brakes, and after sway is under control, then resume throttle ?
Termed, Toyota smart stop technology, this feature can be disabled on some other makes apparently, but I do not find a way to disable it on a Toyota (not surprising since they were hit so hard for what was mostly driver error).
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I would say yes, especially with front wheel drive. Letting up on the throttle will throw the sway of the trailer forward towards the wheels with drag on them, making the tail more apt to try to wag the dog. In some extreme cases accelerating is the solution, especially if the trailer is tongue light to the extreme.
As mentioned, giving the driver the ability to override that feature may be the best answer.
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07-16-2015, 09:39 AM
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#13
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Senior Member
Trailer: 1973 Compact Jr and 1980 Bigfoot 17 ft
Posts: 1,339
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I have owned 3 Toyota Siennas (2003, 2006, & 2011) and towed with all of they. They have all been capable tow vehicles and very reliable cars. Toyota is not interested in their use as a tow vehicle and seems worried about resulting liability. All 3 owner manuals contained the following statement; " do not exceed 45 mph when towing or the posted speed limit whichever is lowest".
__________________
1980 Bigfoot 17' & former owner of 1973 Compact Jr
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07-16-2015, 03:18 PM
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#14
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Senior Member
Trailer: 2009 Trillium 13 ft ('Homelet') / 2000 Subaru Outback
Posts: 2,222
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It is a design feature
"Since the advent of electronic throttle control, many automakers have added software to program the throttle to close—and therefore cut power—when the brakes are applied. Cars from BMW, Chrysler, Nissan/Infiniti, Porsche, and Volkswagen/Audi have this feature, and that’s precisely why the G37 aced this test."
From this article:
How To Deal With Unintended Acceleration - Tech Dept. - Car and Driver
Shutting down the throttle is preferable to shutting off the engine which would remove power steering/brakes.
I understand that some people have stomped on both in panic situations.
The answer:
Don't apply brakes in any fashion while the throttle is open.
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