Thoughts on LS430 rough shifting and A761e transmission
03-08-19, 11:52 PM
#16
Lexus Champion
I would like to add to your thoughts that Lexus/Toyota decided that issuing TSB on A761e harsh shifting wasn't necessary most likely due to insufficient statistics. I am not surprised at all that most LS430 owners do not experience transmission problems, which is a great sign. What I do believe is due to construction and placement of ECM, the heating problem (very valid here in Florida) could contribute to some sort of electronics circuitry problem. But this is just an assumption.
I will definitely share the results of the fix, hopefully they do some magic.
I will definitely share the results of the fix, hopefully they do some magic.
ECU placement in the engine compatment is a BAD idea.
The manufacturer saves a little weight and a few $ by shortening the wire harness is a poor excuse for placing an ECU in the engine compartment.
I have seen ECUs adjacent to an unshielded turbo charger with only a token barrier...never mind the heat soak spillover over the top.
Electronics abhor heat.
Last edited by YODAONE; 03-08-19 at 11:56 PM.
03-09-19, 06:19 AM
#17
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The ECU on LS400 is correctly on passenger side of firewall behind glovebox.
ECU placement in the engine compatment is a BAD idea.
The manufacturer saves a little weight and a few $ by shortening the wire harness is a poor excuse for placing an ECU in the engine compartment.
I have seen ECUs adjacent to an unshielded turbo charger with only a token barrier...never mind the heat soak spillover over the top.
Electronics abhor heat.
ECU placement in the engine compatment is a BAD idea.
The manufacturer saves a little weight and a few $ by shortening the wire harness is a poor excuse for placing an ECU in the engine compartment.
I have seen ECUs adjacent to an unshielded turbo charger with only a token barrier...never mind the heat soak spillover over the top.
Electronics abhor heat.
03-09-19, 06:35 AM
#18
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Peacebay, To save time and effort to reset ECM without battery disconnect. https://www.clublexus.com/forums/sc430-2nd-gen-2001-2010/529464-how-do-you-reset-the-ecu.html Post 5 from Harold does the trick.
03-09-19, 05:19 PM
#19
Yes it does. Peacebay and my Ls do the same thing after I reset. Goes along fine and seems to slowly learn to shift poorly again. I am trying different accelerating techniques at this point and will keep you posted. Hope SIA works for both of you!
Last edited by Phillib4; 03-09-19 at 05:23 PM. Reason: Correction
03-10-19, 03:14 PM
#21
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I do believe that these symptoms are due to electrical part, not mechanical. Aisin is way too robust to start showing poor shifting after just 100k even if the oil is dirty/low quality. Something tells me that controlling module is not able to properly adjust the work of solenoids and evaluate speed of transmission shafts after learning the driving pattern.
03-10-19, 03:27 PM
#22
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If this is somehow proven by whoever is repairing transmissions or is an expert in automotive electronics, we may know exactly what is the best solution. So fast, SIA electronics claim they know what they are doing.
03-10-19, 05:12 PM
#23
Lexus Champion
Hope you get it worked out. These are extremely extremely robust transmissions. I've had a fluid exchange once at about 114k (142k now), still shifts brand new and like butter.
I do have the low speed lurch issue (mine's an '04) but I never got around to dealing with it, as it hardly ever does it where I live and drive.
When I lived in LA that was a different story, though lol.
I do have the low speed lurch issue (mine's an '04) but I never got around to dealing with it, as it hardly ever does it where I live and drive.
When I lived in LA that was a different story, though lol.
03-10-19, 07:20 PM
#25
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https://www.photobox.co.uk/my/photo/...d=501718608246
The image of LS430 internal ECM board shows the main suspect - the tiny hardware memory chip. IMHO reset procedures do not allow to clear its code into zeros to restart communication between engine and transmission.
The image of LS430 internal ECM board shows the main suspect - the tiny hardware memory chip. IMHO reset procedures do not allow to clear its code into zeros to restart communication between engine and transmission.
Last edited by ls430w140; 03-10-19 at 07:24 PM.
03-10-19, 08:26 PM
#26
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The following 2 users liked this post by ls430w140:
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03-12-19, 05:38 AM
#27
I agree the transmission servicing could be an issue as it is an unknown. Be it wrong fluid, overfill/underfill, ECM plenty of possibilities. Just looking for a solution. Strange that after ECM reset the shifts are ok. Also own 121k mile 02 LS430 that I have serviced from new(30k fluid changes) The a650 and the a761 are very similar in the shift patterns. The low speed fast accel slight shift lag is the most noticeable to me. Vehicle before 02 LS was 1990 Maxima that was sold at 355k, trans never touched for any problem(many fluid changes). Doubt any transmission will go 350k without fluid being refreshed. Looking forward to hear the results on the SIA fix and longer term report on SIA repair. Thanks in advance to Lex in FL,Peacebay and Ls430w140.
Last edited by Phillib4; 04-05-19 at 04:01 AM.
03-12-19, 07:04 AM
#28
I had this issue happen over the summer and sent ECU into SIA. They had it back to me within a week and the problem has not come back. You can check my post history on exact timeline, but turnaround was very quick and I am very satisfied with the service I received form SIA.
03-12-19, 10:21 AM
#29
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My ECM is on the way back home. SIA said they discovered transmission module problem and successfully repaired it. Next Monday I ll post the results to see if this is an effective solution to ls430 transmission problems.
SIA said they discovered transmission module problem and successfully repaired it. Next Monday I ll post the results to see if this is an effective solution to ls430 transmission problems.
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jonathanz (03-12-19)
03-12-19, 11:15 AM
#30
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Would you be willing to open your ECM and snap some pictures? It would be nice to know what the issue being repaired is.