6 speed auto concern

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11-24-18 | 05:14 PM

#16

Gs21

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Joined: Aug 2016

Posts: 53

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From: New york

Quote:

Originally Posted by er34

Yes, downshifting in autos is completely normal... otherwise the engine would either stall, or the car will bog when you get back on the gas. But it's difficult for us to tell how much "lurch" you are experiencing, mine is pretty smooth.

Do you notice the revs go up a bit when you come to a stop at around 5mph downshifing into 1st gear?

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11-25-18 | 12:10 PM

#17

bclexus

Lexus Test Driver

Joined: Nov 2014

Posts: 9,644

Likes: 2,330

From: Texas

Quote:

Originally Posted by Gs21

The thing is he accelerated while in drive maybe about 5 feet and then through it in reverse, and repeated that about 4 times back and forth

Its almost like something happended to first gear because the car can never downshift smoothly into 1st when coming to a stop. Its similar to if you down****ing into 1 st gear in a manual car but not as harsh but still you feel the car lurch a bit and its just annoying.

When a transmission has an 'overly' or 'unusually' harsh or abrupt downshift from second gear into first gear the cause can be anything from being acceptably normal due to the transmission fluid and/or engine not up to typical operating temperature to a real problem such as (i) a shift solenoid that is sticking or is showing signs of failure, or (ii) the ECU software that has become glitched. It could even be caused by worn-out automatic transmission fluid, which is highly unlikely in your case. As for the harsh downshift being 'acceptably normal' I mean that it does not throw a CEL code (e.g. P0751), and therefore is not considered by Lexus to be a problem the car maker should waste diagnostic time, parts and labor to fix when there is no indication there is an actual problem.

Also, keep in mind that your transmission and engine operating parameters are changed when you are in different Drive Modes, with the Sport modes increasing the shift line pressure which often makes for distinguished shift characteristics that are more pronounced and perceived.

You can be assured that whatever the Lexus technician did two years ago that you did not like seeing him do did not cause or create this ongoing perception that there is a problem.

Two years ago when you had the car in for "diagnosing" when the technician shifted to change directions five times without coming to a stop, what problem were they diagnosing for you? Was it anything to do with the transmission?

Your car is designed to let you know when there is a problem. If your car's CEL had thrown one of the following codes I'm sure that your Lexus dealer would have been glad to take care of the problem, but since it didn't they are not going to just start digging for an unknown and undisclosed problem.

Diagnostic Trouble Codes P0700 thru P0799

P0700....Transmission Control System (MIL Request)
P0701....Transmission Control System Range/Performance
P0702....Transmission Control System Electrical
P0703....Torque Converter/Brake Switch B Circuit
P0704....Clutch Switch In put Circuit Malfunction
P0705....Transmission Range Sensor Circuit Malfunction (PRNDL Input)
P0706....Transmission Range Sensor Circuit Range/Performance
P0707....Transmission Range Sensor Circuit Low Input
P0708....Transmission Range Sensor Circuit High Input
P0709....Transmission Range Sensor Circuit intermittent
P0710....Transmission Fluid Temperature Sensor Circuit
P0711....Transmission Fluid Temperature Sensor Circuit Range/Performance
P0712....Transmission Fluid Temperature Sensor Circuit Low Input
P0713....Transmission Fluid Temperature Sensor Circuit High Input
P0714....Transmission Fluid Temperature Sensor Circuit Intermittent
P0715....Input/Turbine Speed Sensor Circuit
P0716....Input/Turbine Speed Sensor Circuit Range/Performance
P0717....Input/Turbine Speed Sensor Circuit No Signal
P0718....Input/Turbine Speed Sensor Circuit Intermittent
P0719....Torque Converter/Brake Switch B Circuit Low
P0720....Output Speed Sensor Circuit
P0721....Output Speed Sensor Circuit Range/Performance
P0722....Output Speed Sensor Circuit No Signal
P0723....Output Speed Sensor Circuit Intermittent
P0724....Torque Converter/Brake Switch B Circuit High
P0725....Engine Speed Input Circuit
P0726....Engine Speed Input Circuit Range/Performance
P0727....Engine Speed Input Circuit No Signal
P0728....Engine Speed Input Circuit Intermittent
P0730....Incorrect Gear Ratio
P0731....Gear 1 Incorrect Ratio
P0732....Gear 2 Incorrect Ratio
P0733....Gear 3 Incorrect Ratio
P0734....Gear 4 Incorrect Ratio
P0735....Gear 5 Incorrect Ratio
P0736....Reverse Incorrect Ratio
P0737....TCM Engine Speed Output Circuit
P0739....TCM Engine Speed Output Circuit Low
P0739....TCM Engine Speed Output Circuit High
P0740....Torque Converter Clutch Circuit
P0741....Torque Converter Clutch Circuit Performance or Stuck Off
P0742....Torque Converter Clutch Circuit Stuck On
P0743....Torque Converter Clutch Circuit Electrical
P0744....Torque Converter Clutch Circuit Intermittent
P0745....Pressure Control Solenoid 'A'
P0746....Pressure Control Solenoid 'A' Performance or Stuck Off
P0747....Pressure Control Solenoid 'A' Stuck On
P0748....Pressure Control Solenoid 'A' Electrical
P0749....Pressure Control Solenoid 'A' Intermittent
P0750....Shift Solenoid 'A'
P0751....Shift Solenoid 'A' Performance or Stuck Off
P0752....Shift Solenoid 'A' Stuck On
P0753....Shift Solenoid 'A' Electrical
P0754....Shift Solenoid 'A' Intermittent
P0765....Shift Solenoid 'B'
P0756....Shift Solenoid 'B' Performance or Stuck Off
P0757....Shift Solenoid 'B' Stuck On
P0758....Shift Solenoid 'B' Electrical
P0759....Shift Solenoid 'B' Intermittent
P0760....Shift Solenoid 'C'
P0761....Shift Solenoid 'C' Performance or Stuck Off
P0762....Shift Solenoid 'C' Stuck On
P0763....Shift Solenoid 'C' Electrical
P0764....Shift Solenoid 'C' Intermittent
P0765....Shift Solenoid 'C'
P0766....Shift Solenoid 'D' Performance or Stuck Off
P0767....Shift Solenoid 'D' Stuck On
P0768....Shift Solenoid 'D' Electrical
P0769....Shift Solenoid 'D' Intermittent
P0770....Shift Solenoid 'E'
P0771....Shift Solenoid 'E' Performance or Stuck Off
P0772....Shift Solenoid 'E' Stuck On
P0773....Shift Solenoid 'E' Electrical
P0774....Shift Solenoid 'E' Intermittent
P0775....Pressure Control Solenoid 'B'
P0776....Pressure Control Solenoid 'B' Performance or Stuck Off
P0777....Pressure Control Solenoid 'B' Stuck On
P0778....Pressure Control Solenoid 'B' Electrical
P0779....Pressure Control Solenoid 'B' Intermittent
P0780....Shift
P0781....1-2 Shift
P0782....2-3 Shift
P0783....3-4 Shift
P0784....4-5 Shift
P0785....Shift/Timing Solenoid
P0786....Shift/Timing Solenoid Range/Performance
P0787....Shift/Timing Solenoid Low
P0788....Shift/Timing Solenoid High
P0789....Shift/Timing Solenoid Intermittent
P0790....Normal/Performance Switch Circuit
P0791....Intermediate Shaft Speed Sensor Circuit
P0792....Intermediate Shaft Speed Sensor Circuit Range/Performance
P0793....Intermediate Shaft Speed Sensor Circuit No Signal
P0794....Intermediate Shaft Speed Sensor Circuit Intermittent
P0795....Pressure Control Solenoid 'C'
P0796....Pressure Control Solenoid 'C' Performance or Stuck off
P0797....Pressure Control Solenoid 'C' Stuck On
P0798....Pressure Control Solenoid 'C' Electrical
P0799....Pressure Control Solenoid 'C' Intermittent

Last edited by bclexus; 11-25-18 at 03:49 PM.

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11-26-18 | 07:39 AM

#18

drgrant

Instructor

Joined: May 2015

Posts: 777

Likes: 120

From: MA

Quote:

Originally Posted by Gs21

I addressed it the same day infront of the lexus specialist that did it and the shop foreman and two other lexus employee from the dealership all in the same room. Ofcourse they all dismissed me and he denied it and got pissed that I confronted him about it with them in the room. I been experiencing it since then but as long the car is driving lexus does not give a F***. My word against theirs? I stand no chance

This leads me to another question... why were they doing this "test" to begin with? Seems kind of odd, absent some other problem. I've never heard of anyone doing
this.

-Mike

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12-02-18 | 03:40 PM

#19

Gs21

Thread Starter

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Joined: Aug 2016

Posts: 53

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From: New york

Quote:

Originally Posted by drgrant

This leads me to another question... why were they doing this "test" to begin with? Seems kind of odd, absent some other problem. I've never heard of anyone doing
this.

-Mike

He was diagnosing a problem where it was hard to get the car out of Park without using a bit of force on the shifter.

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12-02-18 | 03:44 PM

#20

Gs21

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Joined: Aug 2016

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From: New york

Quote:

Originally Posted by bclexus

Thanks for the info, I’m not sure where I would start to fix this problem. Is it easy to replace the downshift solenoid? or somehow relash the software that controls the transmission

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12-02-18 | 04:38 PM

#21

bclexus

Lexus Test Driver

Joined: Nov 2014

Posts: 9,644

Likes: 2,330

From: Texas

Quote:

Originally Posted by Gs21

Thanks for the info, I’m not sure where I would start to fix this problem. Is it easy to replace the downshift solenoid? or somehow relash the software that controls the transmission

You are like a dog with a bone! Lexus obviously does not consider your concern to be a problem. I presume you could replace the downshift solenoid and reinstall the shift control software and there wouldn't be any difference. If you could somehow make arrangements to have a Lexus technician drive your car and another GS 350 back-to-back maybe he can gain an understanding of what you are experiencing and possibly address it. But, going on a helter-skelter campaign to replace things isn't the answer in my opinion...