2005 LS430 Car Jolts (Jerk) when downshifts from 2 to 1
02-17-18, 01:24 PM
#61
Rookie
Thread Starter
Ok... thanks for your clarification.and presenting a diagram....THERE IS A THROTTLE POSITION SEBSOR contained within the THROTTLE BODY on the 2004-2006 LS430...
So back to my original comment....Have your throttle body TPS checked.
One thing this diagram provides are symbols for the Pedal Position Sensor and Throttle Position Sensor...they are both dual variable resistors...on each sensor one track reads when accelerator pedal is moving in one direction and the other the opposite direction so acceleration and deceleration activity is accurately read by ECU.
If a worn spot in the variable resistor, then ECU's reading of resistance will suffer.
This may be hard to derect without removing the parts and actuallu hooking up to a multimeterto check resistance across the sweep of both tracks of TPS and Pedal Position Sensor
These sensors are electromechanical devices and they do wear out, so worth looking into first.
There is also a motor and (clutch?) in your throttle body to consider.
Sometimes the dealer technician has tthe benefit of having a spare part on hand to assist with trouble-shooting...
So back to my original comment....Have your throttle body TPS checked.
One thing this diagram provides are symbols for the Pedal Position Sensor and Throttle Position Sensor...they are both dual variable resistors...on each sensor one track reads when accelerator pedal is moving in one direction and the other the opposite direction so acceleration and deceleration activity is accurately read by ECU.
If a worn spot in the variable resistor, then ECU's reading of resistance will suffer.
This may be hard to derect without removing the parts and actuallu hooking up to a multimeterto check resistance across the sweep of both tracks of TPS and Pedal Position Sensor
These sensors are electromechanical devices and they do wear out, so worth looking into first.
There is also a motor and (clutch?) in your throttle body to consider.
Sometimes the dealer technician has tthe benefit of having a spare part on hand to assist with trouble-shooting...
so YODAONE it sound like I need hook up and measure the resistance on Pedal Position Sensor and Throttle Position Sensor. I assume I do that after I put back the ECU.
02-27-18, 04:29 PM
#62
Rookie
Thread Starter
Sorry for the delay but I finally got my ECU back last night from SIA Electronics. It looks like they finally fixed it correctly and the gear shift issue has been fixed.
Here is the summary of what happened.
1, The car started jolting when it down shifted from gear 2 to 1
2, Got a appointment with the Lexus dealer but it was a week away
3. Took it to a local Toyota certified Master Technician, He checked the Transmission fluid level, recommended flushing the Transmission. Cost $50
4. Took to a Transmission expert, He said Transmission is OK, recommended taking it to Lexus. Cost $90
5. Took it to Lexus dealer. They Said it is the ECU, which would cost $2272 to replace. Service cost $116
6. Send the ECU to SIA. Cost $135 + $15 (S&H) + $5 (Insurance) = $155
7. Got the ECU back 10 days later, Installed it but has the same problem
8. Spoke with Lexus, they questioned the Transmission fluid level. So asked them drain fluid and new and check level and then run the diagnostics again on the ECU. Two days later they told me the ECU is bad and the fluid level change will not make a difference. When I asked for the diagnostic printouts they told me there are NO diagnostic tests they have for the ECU. When they see this problem they replace ECU. Cost for the service $0.
9. Spoke with SIA, sent the ECU back to them. Cost $15 (S&H). Warranty covers the part for lifetime.
10 Got the ECU back 10 days later, Installed it and it worked.
11. Total money spent $426 (some was wasted)
If you have this problem I think you should do the following:
1. Remove the ECU and send it to online repair shop. But get someone on the phone to get a verbal commitment for the turnaround time.Because SIA on their site advertises 2 days which is incorrect. If you are OK to wait 10 days then feel free to use them.
2. Install and if it does not fix the problem, then take it to a Lexus dealer for then to diagnose the problem.
3. Then follow one the steps above.
Thanks you all for sticking around and giving all the valuable input.
Here is the summary of what happened.
1, The car started jolting when it down shifted from gear 2 to 1
2, Got a appointment with the Lexus dealer but it was a week away
3. Took it to a local Toyota certified Master Technician, He checked the Transmission fluid level, recommended flushing the Transmission. Cost $50
4. Took to a Transmission expert, He said Transmission is OK, recommended taking it to Lexus. Cost $90
5. Took it to Lexus dealer. They Said it is the ECU, which would cost $2272 to replace. Service cost $116
6. Send the ECU to SIA. Cost $135 + $15 (S&H) + $5 (Insurance) = $155
7. Got the ECU back 10 days later, Installed it but has the same problem
8. Spoke with Lexus, they questioned the Transmission fluid level. So asked them drain fluid and new and check level and then run the diagnostics again on the ECU. Two days later they told me the ECU is bad and the fluid level change will not make a difference. When I asked for the diagnostic printouts they told me there are NO diagnostic tests they have for the ECU. When they see this problem they replace ECU. Cost for the service $0.
9. Spoke with SIA, sent the ECU back to them. Cost $15 (S&H). Warranty covers the part for lifetime.
10 Got the ECU back 10 days later, Installed it and it worked.
11. Total money spent $426 (some was wasted)
If you have this problem I think you should do the following:
1. Remove the ECU and send it to online repair shop. But get someone on the phone to get a verbal commitment for the turnaround time.Because SIA on their site advertises 2 days which is incorrect. If you are OK to wait 10 days then feel free to use them.
2. Install and if it does not fix the problem, then take it to a Lexus dealer for then to diagnose the problem.
3. Then follow one the steps above.
Thanks you all for sticking around and giving all the valuable input.
Last edited by LexInFL; 02-27-18 at 04:34 PM.
02-28-18, 01:42 PM
#63
i had this problem several months ago, it feels like someone is slamming into the back of the car when shifting from 2 to 1 when braking. The harder you braked, the harder the rear end slam. But then I took a long fast drive to Florida, about a thousand miles and it hasn't happened since.
02-28-18, 04:38 PM
#64
Rookie
Thread Starter
i had this problem several months ago, it feels like someone is slamming into the back of the car when shifting from 2 to 1 when braking. The harder you braked, the harder the rear end slam. But then I took a long fast drive to Florida, about a thousand miles and it hasn't happened since.
. Maybe you just become immune to it after a 1000 miles 
Yes that is problem I was having. Not sure why driving would fix the problem other than the heat somehow fixing some lose connection on the ECU board. It looks like a common problem on the LS and GS but no recall by Lexus. They have to get sued before they recall.
03-01-18, 06:58 AM
#65
yeah a loose ECU connection is plausible. I suppose something may have gotten gummed up inside the trans and a long hot drive loosened it. Not sure, i only know it hasn't come back, even after repeating the exact braking pattern. Am a bit surprised Lexus isn't on this more, with aggressive braking the slam is really quite violent and shoves the car forward several feet. If that happened to my wife she would freak.
07-28-18, 04:25 PM
#67
Driver School Candidate
LexInFL - You are a star!!! Thank you. Thank you.
Sorry for the delay but I finally got my ECU back last night from SIA Electronics. It looks like they finally fixed it correctly and the gear shift issue has been fixed.
Here is the summary of what happened.
1, The car started jolting when it down shifted from gear 2 to 1
2, Got a appointment with the Lexus dealer but it was a week away
3. Took it to a local Toyota certified Master Technician, He checked the Transmission fluid level, recommended flushing the Transmission. Cost $50
4. Took to a Transmission expert, He said Transmission is OK, recommended taking it to Lexus. Cost $90
5. Took it to Lexus dealer. They Said it is the ECU, which would cost $2272 to replace. Service cost $116
6. Send the ECU to SIA. Cost $135 + $15 (S&H) + $5 (Insurance) = $155
7. Got the ECU back 10 days later, Installed it but has the same problem
8. Spoke with Lexus, they questioned the Transmission fluid level. So asked them drain fluid and new and check level and then run the diagnostics again on the ECU. Two days later they told me the ECU is bad and the fluid level change will not make a difference. When I asked for the diagnostic printouts they told me there are NO diagnostic tests they have for the ECU. When they see this problem they replace ECU. Cost for the service $0.
9. Spoke with SIA, sent the ECU back to them. Cost $15 (S&H). Warranty covers the part for lifetime.
10 Got the ECU back 10 days later, Installed it and it worked.
11. Total money spent $426 (some was wasted)
If you have this problem I think you should do the following:
1. Remove the ECU and send it to online repair shop. But get someone on the phone to get a verbal commitment for the turnaround time.Because SIA on their site advertises 2 days which is incorrect. If you are OK to wait 10 days then feel free to use them.
2. Install and if it does not fix the problem, then take it to a Lexus dealer for then to diagnose the problem.
3. Then follow one the steps above.
Thanks you all for sticking around and giving all the valuable input.
Here is the summary of what happened.
1, The car started jolting when it down shifted from gear 2 to 1
2, Got a appointment with the Lexus dealer but it was a week away
3. Took it to a local Toyota certified Master Technician, He checked the Transmission fluid level, recommended flushing the Transmission. Cost $50
4. Took to a Transmission expert, He said Transmission is OK, recommended taking it to Lexus. Cost $90
5. Took it to Lexus dealer. They Said it is the ECU, which would cost $2272 to replace. Service cost $116
6. Send the ECU to SIA. Cost $135 + $15 (S&H) + $5 (Insurance) = $155
7. Got the ECU back 10 days later, Installed it but has the same problem
8. Spoke with Lexus, they questioned the Transmission fluid level. So asked them drain fluid and new and check level and then run the diagnostics again on the ECU. Two days later they told me the ECU is bad and the fluid level change will not make a difference. When I asked for the diagnostic printouts they told me there are NO diagnostic tests they have for the ECU. When they see this problem they replace ECU. Cost for the service $0.
9. Spoke with SIA, sent the ECU back to them. Cost $15 (S&H). Warranty covers the part for lifetime.
10 Got the ECU back 10 days later, Installed it and it worked.
11. Total money spent $426 (some was wasted)
If you have this problem I think you should do the following:
1. Remove the ECU and send it to online repair shop. But get someone on the phone to get a verbal commitment for the turnaround time.Because SIA on their site advertises 2 days which is incorrect. If you are OK to wait 10 days then feel free to use them.
2. Install and if it does not fix the problem, then take it to a Lexus dealer for then to diagnose the problem.
3. Then follow one the steps above.
Thanks you all for sticking around and giving all the valuable input.
I have a 2004 LS430 (127K miles). The same problem occurred to me with harsh 2-1 downshift. I brought it to Lexus dealer and they had master technician look at it for 2 hours. They told me the transmission is going bad. I show them Technical Service Information Bulletin L-SB-0126-12 (December 4, 2012). They still insisted that it was for GS. LS never had this problem. He also mentioned that ES has the same problem. I sent my ECU to SIA for repair. Within hours after they received my ECU, they fixed the problem. I asked them how could they be sure that the problem was fixed. He told me that they received about 12 cases with the same problem every week. After I received the repaired ECU, I did transmission flush twice. And the car is running like new now. Lexus really needs to put out another TSIB to warn LS owners.
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03-11-19, 06:27 PM
#69
LexInFL, it seems that more and more lexus forum members are discovering that ECM is the reason for poor shifting quality. Can i ask you to share your thoughts on how shifting works for you as of today after half a year driving with the new ECM on board?
09-09-20, 12:35 PM
#70
Driver School Candidate
I had this same problem. I pulled the ECM and sent it to SAI electronics ( https://siaelec.com ). They reprogrammed it. Perfect fix. I sent it the Tuesday before Labor Day weekend. I had it back the Wednesday after Labor Day....8 days total. $180.00. Fixed problem after being told there were trans problems.
09-10-20, 10:33 PM
#72
Rookie
Thread Starter
No problem with the shifting after the fix.
10-24-21, 06:57 PM
#74
Driver School Candidate
Join Date: Oct 2021
Location: CA
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Original Post by LexInFL:
I have the exact same problem on my 2005 Lexus LS430 with 160K miles. I have a few questions regarding your suggested course of action:
1. Where is the ECU located and is it easy to remove. If there is a link to instructions or a video on how to remove it, can you please post.
2. When you contact SIA (https://siaelec.com), what issue(s) are you asking them to fix. Or are you just asking them to fix to factory specs.
3. When you get the ECU back from SIA is there any reprogramming you have to do to ensure it works on your Lexus / Key. Or not needed if it is your car's ECU unit.
Thanks,
If you have this problem I think you should do the following:
1. Remove the ECU and send it to online repair shop. But get someone on the phone to get a verbal commitment for the turnaround time.Because SIA on their site advertises 2 days which is incorrect. If you are OK to wait 10 days then feel free to use them.
2. Install and if it does not fix the problem, then take it to a Lexus dealer for then to diagnose the problem.
3. Then follow one the steps above.
1. Remove the ECU and send it to online repair shop. But get someone on the phone to get a verbal commitment for the turnaround time.Because SIA on their site advertises 2 days which is incorrect. If you are OK to wait 10 days then feel free to use them.
2. Install and if it does not fix the problem, then take it to a Lexus dealer for then to diagnose the problem.
3. Then follow one the steps above.
1. Where is the ECU located and is it easy to remove. If there is a link to instructions or a video on how to remove it, can you please post.
2. When you contact SIA (https://siaelec.com), what issue(s) are you asking them to fix. Or are you just asking them to fix to factory specs.
3. When you get the ECU back from SIA is there any reprogramming you have to do to ensure it works on your Lexus / Key. Or not needed if it is your car's ECU unit.
Thanks,
11-15-21, 10:51 PM
#75
Driver School Candidate
Sorry for the delay but I finally got my ECU back last night from SIA Electronics. It looks like they finally fixed it correctly and the gear shift issue has been fixed.
Here is the summary of what happened.
1, The car started jolting when it down shifted from gear 2 to 1
2, Got a appointment with the Lexus dealer but it was a week away
3. Took it to a local Toyota certified Master Technician, He checked the Transmission fluid level, recommended flushing the Transmission. Cost $50
4. Took to a Transmission expert, He said Transmission is OK, recommended taking it to Lexus. Cost $90
5. Took it to Lexus dealer. They Said it is the ECU, which would cost $2272 to replace. Service cost $116
6. Send the ECU to SIA. Cost $135 + $15 (S&H) + $5 (Insurance) = $155
7. Got the ECU back 10 days later, Installed it but has the same problem
8. Spoke with Lexus, they questioned the Transmission fluid level. So asked them drain fluid and new and check level and then run the diagnostics again on the ECU. Two days later they told me the ECU is bad and the fluid level change will not make a difference. When I asked for the diagnostic printouts they told me there are NO diagnostic tests they have for the ECU. When they see this problem they replace ECU. Cost for the service $0.
9. Spoke with SIA, sent the ECU back to them. Cost $15 (S&H). Warranty covers the part for lifetime.
10 Got the ECU back 10 days later, Installed it and it worked.
11. Total money spent $426 (some was wasted)
If you have this problem I think you should do the following:
1. Remove the ECU and send it to online repair shop. But get someone on the phone to get a verbal commitment for the turnaround time.Because SIA on their site advertises 2 days which is incorrect. If you are OK to wait 10 days then feel free to use them.
2. Install and if it does not fix the problem, then take it to a Lexus dealer for then to diagnose the problem.
3. Then follow one the steps above.
Thanks you all for sticking around and giving all the valuable input.
Here is the summary of what happened.
1, The car started jolting when it down shifted from gear 2 to 1
2, Got a appointment with the Lexus dealer but it was a week away
3. Took it to a local Toyota certified Master Technician, He checked the Transmission fluid level, recommended flushing the Transmission. Cost $50
4. Took to a Transmission expert, He said Transmission is OK, recommended taking it to Lexus. Cost $90
5. Took it to Lexus dealer. They Said it is the ECU, which would cost $2272 to replace. Service cost $116
6. Send the ECU to SIA. Cost $135 + $15 (S&H) + $5 (Insurance) = $155
7. Got the ECU back 10 days later, Installed it but has the same problem
8. Spoke with Lexus, they questioned the Transmission fluid level. So asked them drain fluid and new and check level and then run the diagnostics again on the ECU. Two days later they told me the ECU is bad and the fluid level change will not make a difference. When I asked for the diagnostic printouts they told me there are NO diagnostic tests they have for the ECU. When they see this problem they replace ECU. Cost for the service $0.
9. Spoke with SIA, sent the ECU back to them. Cost $15 (S&H). Warranty covers the part for lifetime.
10 Got the ECU back 10 days later, Installed it and it worked.
11. Total money spent $426 (some was wasted)
If you have this problem I think you should do the following:
1. Remove the ECU and send it to online repair shop. But get someone on the phone to get a verbal commitment for the turnaround time.Because SIA on their site advertises 2 days which is incorrect. If you are OK to wait 10 days then feel free to use them.
2. Install and if it does not fix the problem, then take it to a Lexus dealer for then to diagnose the problem.
3. Then follow one the steps above.
Thanks you all for sticking around and giving all the valuable input.
Thanks for your post, I was able to save $2400 due to Lexus dealers. They are a scam.
Sia was taking 10 days to return, ebay price was really good.
But I sent it to Digital auto Technology in Riverside,CA, Almost double price but they shipped next day after fixing it.
My son was able to remove and install it back after watching youtube videos, took less than 5 minutes.
Thank you Thank you Thank you!