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Discussion Starter #1
IS 250 jerks into 1st when coming to a stop while in drive. When I put the car in neutral to stop it does not. Got the B solenoid replaced, there are no metal shavings in the transmission (which is 1 1/2 years old), the ECU unit has the latest upgrades. I bought a used ECU and it would not start, then I sent the ECU to get repaired and it did not fix the hard downshift. Car runs fine otherwise. At a loss. ANY SUGGESTIONS please.
 

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Your complaining about a harsh downshift into first at speed. In addition, your wondering why shifting to neutral doesn't help slow down the car. Either its manual and your jamming the fuck out of the shifter through a lockout or doing it with an auto manually which equally begs the question.... Why?
 

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Discussion Starter #3
I guess I didn't explain well enough. This is automatic transmission & when slowing to a stop it auto downshifts smooth except from 2nd to 1st...there is a jerk. Therefore I put the car in neutral when I have to slow to a stop because then it doesn't jerk as it isn't downshifting. It's been to lexus & a tranny mechanic both misdiagnosed with the repairs suggestions listed in my 1st post.
 

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IS 250 jerks into 1st when coming to a stop while in drive. When I put the car in neutral to stop it does not. Got the B solenoid replaced, there are no metal shavings in
the transmission (which is 1 1/2 years old), the ECU unit has the latest upgrades. I bought a used ECU and it would not start, then I sent the ECU to get repaired and it did not fix the hard downshift. Car runs fine otherwise. At a loss. ANY SUGGESTIONS please.
This happened to me exactly as you describe! (hard downshift into 1st )

I own is250 MY2008, 120'000 km, RWD, automatic transmission.

about a week after this happened, the Check Engine light + Check VSC came up, i connected the obd scanner ans saw "P2714 Pressure Control Solenoid "D" Performance/Stuck Off." code.
i disconnected the battery for 10 minutes and the car drove ok again.

after a month, the P2714 error code came up again, I talked with the dealer here and asked about any Updade available for the transmission, he said to come over and check the car and connect it to Lexus-diagnostic-tools and Update the software to see if it will solve the problem.

Im planning to go to him and will let you know in any update.
 

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Discussion Starter #6
Any new info from anyone? All the people I talk to say sell it but how can I sell it with this issue? Having to put it in neutral every time I have to stop is a pain plus I am afraid it may eventually effect something else in the car. Lexus was no help either. Thank you
 

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*Update*

(2nd time) The Error Code P2714 Pressure Control Solenoid "D" Performance/Stuck Off + Check VSC appeared agein 2 weeks ago, I cleared it and the car back to normal.

(3rd time) Today it happened again: P2714+Check VSC + the transmission stuck on 3rd gear and the rpm accelerated, I cleared it and the car back to normal.

(4th time) Today it happened again: P2714+P0751 Shift Solenoid "A" Performance/Stuck Off + Check VSC + the transmission stuck on 3rd gear and the rpm accelerated, I cleared it and the car back to normal.

So I went to the dealer, they did some software update to the transmission (A960E transmission), the vehicle works normally in the meantime.
They charged me for 100$ for the diagnistic+Update.
 

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Any update since Jan? Did the software upgrade do the trick? My 07' IS350 is doing the same thing.

Thanks.
 

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Discussion Starter #9
Shlomie11 I am glad the update helped you. So far no help on this end. If anyone else is having the issue please let us know what your solution was if you got one. The check engine light does come on randomly and goes back off on its own. The code is bad B solenoid which was replaced a year ago when the code first came on but is keeps coming on anyway.

Recap....automatic 2006 is250 hard downshifts into 1st (all on its own) when coming to a stop. I put it in neutral right before stopping to prevent the car from jerking when it shifts into 1st. Transmission is only 2 years old, no metal shavings in it, B solenoid repalced about a year ago, was told by Lexus the computer is updated. Tried a used computer (new ones cost 3000) and it did not work so returned it. Tried a computer repair guy and it did not work so got my $ back.

There is no jamming of the gears or manually shifting, just slowly breaking for a stop light/sign etc.

THANK YOU for any info
 

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ECU repair fixed the hard downshift

My 06 IS250 had 148K miles and I had the same hard downshift from 2nd to 1st around 8 mph. There was no change in RPMs so I thought it was electronic. I took the chance and sent the ECU out for repair and the car was back to normal when I reinstalled the ECU.
 

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Shlomie11 I am glad the update helped you. So far no help on this end. If anyone else is having the issue please let us know what your solution was if you got one. The check engine light does come on randomly and goes back off on its own. The code is bad B solenoid which was replaced a year ago when the code first came on but is keeps coming on anyway.

Recap....automatic 2006 is250 hard downshifts into 1st (all on its own) when coming to a stop. I put it in neutral right before stopping to prevent the car from jerking when it shifts into 1st. Transmission is only 2 years old, no metal shavings in it, B solenoid repalced about a year ago, was told by Lexus the computer is updated. Tried a used computer (new ones cost 3000) and it did not work so returned it. Tried a computer repair guy and it did not work so got my $ back.

There is no jamming of the gears or manually shifting, just slowly breaking for a stop light/sign etc.

THANK YOU for any info
Did you ever figure this out? I have a 2006 IS250 2WD (my own personal car) and it does exactly the same thing, except it slams on the 3 - 2 and the 2 - 1 downshifts. I have no codes. I am actually an A.S.E. Certified Master Tech and run my own shop, and I can't figure this out. I have also talked to my transmission guy and we both thought it to be a speed sensor issue. I replaced SN2 (output shaft speed sensor) and no change. I think it is a stuck solenoid not allowing a clutch to release but with each solenoid around $300 each, I am not going to throw them at it without being reasonably sure it will fix the issue.
 

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Did you ever figure this out? I have a 2006 IS250 2WD (my own personal car) and it does exactly the same thing, except it slams on the 3 - 2 and the 2 - 1 downshifts. I have no codes. I am actually an A.S.E. Certified Master Tech and run my own shop, and I can't figure this out. I have also talked to my transmission guy and we both thought it to be a speed sensor issue. I replaced SN2 (output shaft speed sensor) and no change. I think it is a stuck solenoid not allowing a clutch to release but with each solenoid around $300 each, I am not going to throw them at it without being reasonably sure it will fix the issue.
I have the exact same problem on this exact car. Harsh downshift 2 to 1 started after replacing transmission oil so I assume is related to some little dirt in valve body. Bought another complete reman valve body with solenoids but problem persists after replacement. I did reset ECU per service manual, no difference.
 

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I have the exact same problem on this exact car. Harsh downshift 2 to 1 started after replacing transmission oil so I assume is related to some little dirt in valve body. Bought another complete reman valve body with solenoids but problem persists after replacement. I did reset ECU per service manual, no difference.
It may be your speed sensors.
 

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It may be your speed sensors.
My exact thought. I had a funky reading on SN2 (output shaft sensor) so I replaced it. No change. Input sensor reads perfectly. If I forget to put it into neutral before it downshifts to 2nd it bangs your teeth out, and it is getting worse with some other symptoms now, such as a double clunk when going from park to drive and a sometimes hard shift into 5th. No codes; no leaks; and slamming shifts. I'm over it so I ordered a re-man trans from Lexus and will be replacing it on Saturday.
 

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I have the exact same problem on this exact car. Harsh downshift 2 to 1 started after replacing transmission oil so I assume is related to some little dirt in valve body. Bought another complete reman valve body with solenoids but problem persists after replacement. I did reset ECU per service manual, no difference.
 

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I sent the PCM to a place in Ft Lauderdale that said this is a VERY common issue with 2006 IS250 RWD (not AWD) and 2006 GS300s, but ONLY 2006. Trans solenoid drivers burn up. He replaced them all and like magic, the car is perfect again.
 

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Follow up on this problem for the benefit of future readers: after giving up on fixing this problem myself, I took the car to a generic repair shop. They replaced about 3 transmissions, then figured out the problem was the ECU. Just like kumpy wrote, solenoid drivers are build into ECU and burn up sometimes. My mechanic explained me that since there is no protection circuit between ECU and solenoid, drive circuit is likely to fail. He tried to even explain me how this is related to transmission fluid change on high miles vehicle, but I didn't understand his argument. The point is, you either regularly change trans oil every 40-50k miles, or you leave it alone like factory advice is. Under no circumstance you should change trans oil over 150k miles for the first time, or trans solenoid driver can burn up. I read about this failure, just couldn't believe it it failed on me right after trans oil change. Expensive mistake on my side.
 

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I sent the PCM to a place in Ft Lauderdale that said this is a VERY common issue with 2006 IS250 RWD (not AWD) and 2006 GS300s, but ONLY 2006. Trans solenoid drivers burn up. He replaced them all and like magic, the car is perfect again.
Hello, I think my car just had the exact same problem with you guys after a car wash from yesterday. The car felt like humping whenever I downshift from second to one. Does anyone have any reference regarding the solenoid driver? such as where is the location of it, or how one could possible fix it? I'm a software engineer and half electrical engineer, and if possible would like to give it a hack myself. Thanks in advance!
 

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Follow up on this problem for the benefit of future readers: after giving up on fixing this problem myself, I took the car to a generic repair shop. They replaced about 3 transmissions, then figured out the problem was the ECU. Just like kumpy wrote, solenoid drivers are build into ECU and burn up sometimes. My mechanic explained me that since there is no protection circuit between ECU and solenoid, drive circuit is likely to fail. He tried to even explain me how this is related to transmission fluid change on high miles vehicle, but I didn't understand his argument. The point is, you either regularly change trans oil every 40-50k miles, or you leave it alone like factory advice is. Under no circumstance you should change trans oil over 150k miles for the first time, or trans solenoid driver can burn up. I read about this failure, just couldn't believe it it failed on me right after trans oil change. Expensive mistake on my side.
Changing the ATF after 150k miles and trans failing has nothing to do with driver/solenoid failure. It has everything to do with clutch debris build up in piston seals, valve body, and accumulators. The trans is still alive partly due to this build up because it helps 10+ year old seals to actually seal. ATF is extremely high detergent so when you put new fluid in, it goes through and cleans out a lot of that debris that was keeping things going. I've been an A.S.E. certified Master Tech since 1987 and I have seen this happen over and over again. Trans shops will NOT do a service on a trans with 100k+ miles if it has never been done before. The issue with these PCM's is weak MOSFET transisitors that burn up after a while because they were too small to handle the current long term.
 
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