1jonathan1994
New member
- Joined
- Apr 1, 2020
- Messages
- 8
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- Buick Ownership
- 2001 LeSabre custom
I have a 2001 LeSabre that wont go into overdrive anymore.
NOTE. ALL ABS SENSORS WIRES HAVE BEEN CUT. not by me..
Definitely have evap troubles i dont care to fix so I get codes about that.
Put the car on a good machine and it shows a P1575 code which the machine shows is a Extended travel brake switch circuit code. Im sure the brake sending a false signal would prevent the car from shifting into OD for obvious reasons, but when I do a check the brake pedal activates the:
TCC brake pedal switch works properly at the top of the pedal push
Extended Travel Brake Pedal Switch works properly at the middle/bottom of the brake push.
Computer shows the car should be in 4th when its mechanically not.
So other places online say the P1575 code is something Evap related and Im confused there.
Also P0446, P0113, and P0502 codes. I did forget to plug up the air sensor after a filter change one time so there that code.
THe inputs and outputs of 1,2,3,D in both the dash and transmission test correctly on the computer screen.
Driving the car in diagnostic shows the car as shifting into 4, but tachometer and ratio says not.
Solenoids move each time
first is 1-2 on, 3-4 on
second is 1-2 off, 3-4 on
third is both off
fourth is 1-2 on, 3-4 off
Shift screen show 2 and 3 shifts happen fast with minimal error.
4 shift screen shows NO shift time, but a shift error time comparable to the other shifts.
Line pressure does seem to drop when computer forced into 4th when sitting in park, but still matches what the computer requests as a reference.
Honestly I dont know what is supposed to trigger overdrive and the TCC. Manually switching the car with the computer while in park i can hear something happen from 3 to 4, but even manually COMPUTER switching from 3 to 4 going down the road the rpm's still say its in 3rd the the computer registers 4th. I have no idea how this shift pattern is supposed to work with just 2 solenoids so what other things are in play?
Cruise still works until I push the brakes. In D, the coast unlocks. if while coasting you shift it into 3 then the coast stops and rpms go back up as it locks into 3.
Torque converter seems locked when in 3rd no problem.
One diagnostic screen shows the transmission in OVERTEMP mode, another does not.
I tried the computer forcing OVERTEMP off on that one screen and the car drove no different.
Transmission temperature sensor always shows several dozen degrees colder than ambient.
Transmission fluid temperature sensor hovers under 200F going down the road, but starts out ambient and climbs at an expected rate.
TPS works fine and linear.
motor purrs like a kitten and returns great gas mileage otherwise.
NOTE. ALL ABS SENSORS WIRES HAVE BEEN CUT. not by me..
Definitely have evap troubles i dont care to fix so I get codes about that.
Put the car on a good machine and it shows a P1575 code which the machine shows is a Extended travel brake switch circuit code. Im sure the brake sending a false signal would prevent the car from shifting into OD for obvious reasons, but when I do a check the brake pedal activates the:
TCC brake pedal switch works properly at the top of the pedal push
Extended Travel Brake Pedal Switch works properly at the middle/bottom of the brake push.
Computer shows the car should be in 4th when its mechanically not.
So other places online say the P1575 code is something Evap related and Im confused there.
Also P0446, P0113, and P0502 codes. I did forget to plug up the air sensor after a filter change one time so there that code.
THe inputs and outputs of 1,2,3,D in both the dash and transmission test correctly on the computer screen.
Driving the car in diagnostic shows the car as shifting into 4, but tachometer and ratio says not.
Solenoids move each time
first is 1-2 on, 3-4 on
second is 1-2 off, 3-4 on
third is both off
fourth is 1-2 on, 3-4 off
Shift screen show 2 and 3 shifts happen fast with minimal error.
4 shift screen shows NO shift time, but a shift error time comparable to the other shifts.
Line pressure does seem to drop when computer forced into 4th when sitting in park, but still matches what the computer requests as a reference.
Honestly I dont know what is supposed to trigger overdrive and the TCC. Manually switching the car with the computer while in park i can hear something happen from 3 to 4, but even manually COMPUTER switching from 3 to 4 going down the road the rpm's still say its in 3rd the the computer registers 4th. I have no idea how this shift pattern is supposed to work with just 2 solenoids so what other things are in play?
Cruise still works until I push the brakes. In D, the coast unlocks. if while coasting you shift it into 3 then the coast stops and rpms go back up as it locks into 3.
Torque converter seems locked when in 3rd no problem.
One diagnostic screen shows the transmission in OVERTEMP mode, another does not.
I tried the computer forcing OVERTEMP off on that one screen and the car drove no different.
Transmission temperature sensor always shows several dozen degrees colder than ambient.
Transmission fluid temperature sensor hovers under 200F going down the road, but starts out ambient and climbs at an expected rate.
TPS works fine and linear.
motor purrs like a kitten and returns great gas mileage otherwise.
