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Discussion Starter · #1 ·
I used to have rear occasions where I would not be able switch to Reverse right away...but that seems to become a more frequent issue. Today I had to shift from N to R about 10 times before orange light came on and R was engaged. When reverse is failing to engaged Green N light stays on...but I can clearly hear it trying to switch.(clicking noises in the back of the car). Sometimes after it tries for a little while it does switch to R, and sometimes it just turns off the engine and flashing red light as well as engine light comes on. I don't have any problems with any other gears. Any advise would be appreciated.

Thanks

Alex
 

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Discussion Starter · #2 ·
follow up

Read codes back P1646 and P1647(pointing to ECU), but I have my doubts since I can hear it attempting to switch to reverse(so I am guessing ECU is sending the right signals>?). Also changed Battery today(mine was not in good shape), didn't solve the problem.

Please advise.

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Let me draw your attention to the thread titled..."Trouble shooting the no reverse beep problem on SMT Spyder " on this board, as it probably has the answer to your problem.

Plebian gave me some great advice, and it seems to fit in with your problem.

As a follow up, after I changed the swich that plebian suggested, ( $40 ) everything has been working wonderful, and I thank him again. I was waiting a while longer before giving my great results, but I have now used it for a few hunded miles on short trips with no problems.

Good luck.

Harryco.
 

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Do you let the pump finish building pressure before you shift into reverse? Have you check your reverse sensor by any chance.
 

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Discussion Starter · #5 ·
Thanks for the feedback. Harryco I have read your post...one thing that I do notice is when its not switching in Reverse my back light are not turning on. (was it the same for you?) Back lights only turn on once it actually makes it in R gear. How easy is it to get to those two sensors?(do i need to remove anything)

Edwin I just check and once pump builds up pressure first time I can most likely switch to reverse gear however any further consecutive switches are not as successful...

How do I go about checking a reverse sensor, is there a test i can perform myself.

Thanks

Alex
 

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Check your fluid first, reverse is the first to start showing problems when the fluid starts getting low (don't know exactly why, maybe takes more fluid for the push). After that I would take it to get a full relearn, the select sensor may be starting to go out of it's previous range and that would should fix that.
 

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Hi Alex.
I just typed a long message and then lost it !

Basically. I did as plebian suggested to me, and changed the sensor , number 84210-12040, cost of $38.21 . Both of these switches are the same part number.
I used a 1 and 1/8 inch deep socket to change the part ( $5 ) .... use a long extension to reach down to the part to be changed, and have had no problem since.
It is easy to reach once the airbox is removed from near the battery location.

Good luck.

Harryco.
 

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.I just typed a long message and then lost it !.
I always do a Copy before I Send.. that way if ( When ) the Server Dumps me Off, I have my Post Saved..

If the back Up Lites are not going on, then the Tranny is not confirming reverse, and the TCU will get mad and Ignore the Engine ECU asking for Information.. then you get the 1646/1647 Code.. so it not a Problem with the ECU/TCU, they are just Ignoring each other.. It's actually a Software Bug that should have been fixed by Toyota.. because the Dealers see the 1646/47 and say the ECU/TCU's are bad..

Check the Fluid..
Do a relearn on the Sensors..
Replace the Reverse Switches..


Without actually being at the Back looking at the Shifter on the Trans, I can't tell if the Trans is actually making it to reverse and the 'Confirm in Reverse' Switches are bad, or the Tranny never actually makes it to reverse, and the Reverse Lites do not come on.. ( Catch 22 ).. Either way the TCU uses the Reverse Switch toi confirm reverse..

Good Luck
 

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Discussion Starter · #9 ·
Thanks everyone for your feedback. I have removed airbox today and looked at SMT fluid. Its pretty hard to determine the level of the fluid, however looking inside the container I can definitely see SMT fluid.(I would say definitely over half of that container, it does look pretty dark though). I also disconnected electrical connection from the switches\sensors. I am presuming its a gray and white connectors. (have not unscrewed sensors\switches yet...saved it for the other day) . Put everything together and made sure i didn't break anything. So now, every time pump comes on I always shift in R with no problems.....if I do it two more times and pump does not comes on again...I don' switch. What is considered normal?(how many times can i switch to R without requiring pump to engage)

It sounded like both of the reverse sensors are the same part...could I perform experiment where I swap them and see if that changes failure dynamics? Also was wondering if I was going to do relearn...would you recommend attempting it myself(if its even possible) or take it straight to Toyota dealer. (with page 18 and 19 printed of course)

Thanks again for all your help in this matter.
 

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Discussion Starter · #10 ·
Hey guys. So I replaced SMT fluid (mine indeed was a bit low and pretty dark looking), unfortunately it only works first two times after pump comes on. I tried swapping gray and white cables for reverse switches to see if there is a problem with one of them...results were the same. I have not done relearning yet but i am not sure what that would do...since it works every time after pump comes up.

Please let me know what you think.

Thanks

Alex
 

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I would take it in for a relearn, it would change the numbers in the system for the position sensors and hopefully be able to get into a range where it knows that it's in reverse.
 

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Hey Alex
I have the same exact problem as you: stall in reverse with no reverse lights. I did everything that was recommended from this thread and my reverse problem was not fixed. I took my car to a toyota dealership and they fixed it. They replaced my two back up reverse switch assembly, item number 84210-12040. I hope this helps! gl dude!
 

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Hi all, I feel your pain. Mine wouldn't go into reverse when cold, and generally after couple minutes would do, but now it's constant
When i put it in reverse, reverse light constant, no beeping, can hear it click behind, and it shuts down after 5 seconds, unless you go back to neutral.
No problem passing other gears. Can't check ECU codes myseld with my elm327 since i have an MR-S

What i tried
. I checked the HPU and it runs for 23 seconds which is between the 20-30s boundaries, implying thee SMT fluid is not running low (as reverse is the first to go when that is the case).
. Battery recently changed and no erratic behavior but should check ground terminals on the body and transmission just in case
. Shouldn't be the clutch since an SMT can switch gears even with clutch slipping...
. I used "diag my toyota" android amm with a bluetooth ELM327 OBDII dongle, but my Jap MR-S can't display the ECU error log...
. I bought two http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=251117245068#ht_4401wt_1031 since it's cheap and compatible with 84210-12040 and will try changing before doing a sensor relearn
. will try removing battery to get access to all 3 sensors, and see if after 2 hours disconnected it does sensor relearn (altough relearn on analog sensor why not, but on a switch ???)
. Will try Clean the contacts on the neutral and reverse position sensors (the black grey and white plugs under the airbox)

Links i found that could help:
. http://spyderchat.com/forums/showthread.php?47208-SMT-won-t-go-into-reverse
. http://spyderchat.com/forums/showthread.php?51902-02-mr2-no-reverse&highlight=reverse+sensor
. http://spyderchat.com/forums/showthread.php?48541-Need-help-SMT-reverse-problem-Please-reed!!!!!
. http://spyderchat.com/forums/showthread.php?46221-SMT-to-Manual-Conversion-How-I-did-it..
. http://spyderchat.com/forums/showthread.php?38752-How-does-the-SMT-Work
. http://spyderchat.com/forums/showth...6-any-ideas-what-the-problem-is&highlight=860
. http://spyderchat.com/forums/showth...-reverse-issue-(SMT)&highlight=reverse+sensor
. http://www.justanswer.com/uploads/skyvisions/2008-06-01_181036_02_spider1.pdf

Any assistance welcome
 

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Had same issue. relearn will not solve as it is a switch, not an analog sensor.
What are the SMT logs? you only gave motor DTC code, and if you rev above 1200 rpm, pretty sure the motor doesn't die...

if works more when warm, you have oil in both contacts...

Thread below should help

http://www.mr2roc.org/phpBB3/viewtopic.php?f=11&t=40133#p479073
I had this issue recently and found that my reverse light would light up but the buzzer wouldn't be heard. Pulled codes with Techstream got codes for the reverse switch and ECU fault communication. If you change gears back and forth it would eventually work(especially when it was warm).I remove the two reverse sensors and did a bench test. When the sensor is free it should be open and when push in it should have continuity.I had one that I had to push all the way down(bottom out) to get continuity but the other just had resistance.So if you don't get continuity but instead get resistance that sensor is bad.Tested the new one and it only takes maybe a 16th of an inch to get continuity, compare to the old ones which had to travel 1/4 of an inch.So, if you feel like reverse takes a little longer to engage you are most likely heading to future problems.ALSO KEEP IN MIND THAT THE SENSOR USES A 1-1/16 SOCKET NOT A 1-1/8 AS MENTION ABOVE
 

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which switch

could you guys tell me what one of these switches I am after? I pulled my airbox and battery tray out but there are 3 switches all gray on top. Please help, I am looking for the reverse switch mentioned earlier in this thread. I have intermittent lack of engagement into reverse then red trans light comes on the the engine shuts off and no shift indicator lights on in dash.
 
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