Last post on Mar 15, 2008 at 5:55 AM
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Toyota Sienna, Auto Repair, Scheduled Maintenance, Van
#794 of 2209 Lock-up torque converter - Help please fellow owners.
Jun 08, 2004 (7:02 pm)
I have an 04 LE AWD and think that I am having trouble with the Lock-up Torque converter. In "Drive", when the van goes up an short hill, you can see the rpm go up 200-300 rpm when the lock-up takes hold. It'll go back to the previous rpm's when the incline is over. When I am driving in 4th (ie: the overdrive locked out as required when pulling a trailer), I cannot get the same response with the RPM rising on an incline, so believe that the lock-up has not engaged. If the hill is big enough, the tranny will however downshift into 3rd. I've tried this repeatedly both with trailer in tow and without trailer, with cruise on and off, with the same results. Have had my dealer run their computer diagnostic when we went for a test drive. the results were the same. The computer showed that the lock-up was "off" and was working (went to "on")when braking. They are now raising the issue within the Toyota technical community.
Has anyone else noted this? Could I ask some of you to try this at about 60 mph and let me know what you experience. You just have to cruise at a steady 60 mph or so and check the rpm when you go up a hill. has anyone noticed this when towing a trailer?
My concern is that I want that additional torque when needed when towing the trailer.
Thanks for your help.
#795 of 2209 Re: 2004 Sienna LE 18500 miles Update [cybernut04 #725]
Jun 09, 2004 (5:18 am)
I finally have an opportunity to get the dealer to look at my '04 Sienna for 1) sluggish transmission response and 2) A/C blowing noticeably warmer air when compressor clicks off. I have an appointment this Friday ... but I had a really tough time with the service manager I talked to. He said the transmission thing was normal - that I was just "hitting the shift point" when I experienced a lag. And he said I should run the A/C on recirculated air. He seemed surprised when I mentioned the TSB on the transmission. I really don't have a very good feeling about this. I have taken the van in to this dealer only once before, for the first oil change ... and they neglected to reset the "maintenance needed" light on the dash. First time that came on after the oil change I went digging through the manual to find out what was going on, and I reset the light, but you'd think they would be able to deal with minor things like that. And if they can't, is this a place I want to take the van to? Unfortunately, the closest Toyota dealer to me is not a dealer I would ever want to touch my vehicle - I've had dealings with them before, with my Previa. And if I end up thinking of this other dealer in the same way... maybe that's why Toyota builds a pretty darn good vehicle? 'Cuz their service isn't all that great?
Re: "Many thanks to tolenal for posting this message - I found it very helpful, especially: 4. Pause before transmission engages after depressing gas at low speeds. Resolution: updated software for transmission timing (see Technical Service Bulletin).
"Along with the AC problem I posted about recently, I have experienced this sluggish transmission as well. It will be great to be able to not only describe the situation to the dealer but to reference the TSB on transmission timing."
#796 of 2209 woodytwo
Jun 09, 2004 (10:28 am)
Maybe this explanation will help...
When not "locked up", the torque converter input shaft will always turn faster than its output shaft, that's simply the way it works.
So, when you're driving up an incline and the system downshifts from OD you will oftentimes see two distinct increases in engine RPM. One when the transmission shifts down from OD, and another when the torque converter is unlocked.
I don't know which will happen first and sometimes they will both occur simultaneously, so you will only see one "bump", increase in RPM.
In overdrive the input shaft of the transmission will be turning slower than the output shaft which would normally result in very poor efficiency of the torque converter. Torque converter efficiency increases with increased differences in its input shaft and output shaft.
Since the object of an OD system is to run the engine at a lower and more efficient RPM, less friction and wear, it is extremely beneficial to lock the torque converter's input shaft to its output shaft in OD.
#797 of 2209 Re: Lock-up torque converter - Help please fellow owners. [woodytwo #775]
Jun 11, 2004 (6:56 am)
I don't think the lockup function works in 4th. I leave mine in 4th driving in town and have never seen the RPM change indicating lock-unlock.
(04 XLE Ltd AWD)
#798 of 2209 4th....
Jun 11, 2004 (8:09 am)
Lockup only works in the top, OD, gear. And I would assume that on some models you might never see two separate RPM "bumps".
#799 of 2209 Tire Problems
Jun 11, 2004 (6:47 pm)
I have had my XLE AWD for 10 months now. I was wondering if anyone else was having a problem with the tires wearing out. I have the Dunlop run flat tires. The van went in for an oil change at 10,500 miles. I asked them to check the tires because the steering wheel was shaking. The Toyota service dept told me there was a problem with my tires. They rotated the tires and did an alignment(the alignment was fine). Two weeks later (at 11,100 miles) they put 4 brand new Dunlop tires on the van. At 13,500 miles, I took the van in for an oil change and had them look at the tires because the steering wheel was shaking again. They rotated the tires and aligned it again(the alignment was fine). Toyota had them take pictures of the tires. The service dept had to send in the pictures and the alignment information. The response I received so far is that they are monitoring the situation. At my next oil change they will rotate the tires, take pictures, and align it again. This should be in about 4 weeks. Has any one had a similar problem? Does any one know of a problem with the Dunlop run flat tires?
#800 of 2209 service bulletin ID number or date for retiming transmission
Jun 12, 2004 (1:51 am)
HELP me in advance please....
Does anyone have any ID number or date for the bulletin for "retiming the transmission" that people are quoting? I am sure when I mention it to my service department, they are going to say they don't know what I am talking about. My van always shifts pretty rough in low speeds and I'm going to bring it up as a possible problem on the next visit. I would like to quote the exact service bulletin so they don't deny it is a problem.
They already think I am a troublemaker because I said my front strut was leaking. They said they never saw a bad strut in a new vehicle with less than 1,000 miles on it, period! Well I guess I made history. (They thought I ran over some oil on the road and it splashed up on the strut! And I am not intelligent enough to see fluid is dripping out of a shock! Only a service manager has that technical expertise.)
Unfortunately I was right.
Jun 12, 2004 (7:17 am)
This may be of interest:
You, Your Vehicle and the Technical Service Bulletin (TSB)
Any other dealers nearby? Your's sounds awful. If they give you the run-around this time you might escalate it to Toyota. If the dealer already thinks you are trouble, you may as well live up to their expectations and run them through the customer service hoops!
#803 of 2209 Re: 4th.... [wwest #779]
Jun 12, 2004 (5:17 pm)
Thanks for the reply. Interesting to hear that lock-up only works in overdrive. My service dept and another that I know of, think it should also work in 4th gear. My 98 Sienna, although only 4 speed, the lockup worked in OD and third when i was towing. Is your info generic or specific to the Sienna?