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Home >> Lexus >> 2024 >> TX 350 Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 87 (Hybrid Transaxle System (Pc60) - Diagnostic Codes (2 Of 4)) >> Hybrid Transaxle System >> DTC P0840-00: Transmission Fluid Pressure Sensor/Switch "A" Circuit Range/Performance [09/2023 - ] >> Description

DTC P0840-00: Transmission Fluid Pressure Sensor/Switch "A" Circuit Range/Performance [09/2023 - ]: Description

WARNING: This page is about a different car, the 2024 Lexus TX 500h. However, it is still accessible from the selected car via links, so may be relevant.

The TCM performs wet start clutch (WSC) control based on oil pressure signals detected by the oil pressure sensor.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL DTC Output from Priority Note
P0840-00 Transmission Fluid Pressure Sensor/Switch "A" Circuit Range/Performance One of the following conditions is met: (2-trip detection logic)
  • When the engine is started, the integrated value of the oil pressure sensor value minus the WSC oil pressure command value is 215600 kPa (2198.5 kgf/cm2 , 31262 psi) or higher, or -215600 kPa (-2198.5 kgf/cm2 , -31262 psi) or less
  • When the engine is not started, the integrated value of the oil pressure sensor value minus the WSC oil pressure command value is 431200 kPa (4397 kgf/cm2 , 62524 psi) or higher, or -431200 kPa (-4397 kgf/cm2 , -62524 psi) or less
  • It is detected 3 times that the difference between the WSC oil pressure command value and the oil pressure sensor value is 235 kPa (2.4 kgf/cm2 , 34 psi) or higher for 0.5 seconds
  • When the TCM commands SC4 ON, it is detected 3 times that the oil pressure sensor value is higher than the line pressure command value by 490 kPa (5.0 kgf/cm2 , 71 psi) or higher for 1 second
  • When the TCM commands SR ON, it is detected 3 times that the oil pressure sensor value is higher than the line pressure command value by 490 kPa (5.0 kgf/cm2 , 71 psi) or higher for 1 second
  • TCM
  • Transmission wire
  • Transmission valve body assembly
 Comes on Transmission B SAE: P0841
DTC DETECTION CONDITION PATTERNS

  Vehicle Condition
Pattern 1 Pattern 2 Pattern 3 Pattern 4 Pattern 5
Diagnostic Condition Engine is started ◦ - - - -
Engine is not started - ◦ - - -
Ignition switch is ON - - ◦ - -
TCM commands SC4 ON - - - ◦ -
TCM commands SR ON - - - - ◦
Malfunction Condition The integrated value of the oil pressure sensor value minus the WSC oil pressure command value is 215600 kPa (2198.5 kgf/cm2 , 31262 psi) or higher, or -215600 kPa (-2198.5 kgf/cm2 , -31262 psi) or less ◦ - - - -
The integrated value of the oil pressure sensor value minus the WSC oil pressure command value is 431200 kPa (4397 kgf/cm2 , 62524 psi) or higher, or -431200 kPa (-4397 kgf/cm2 , -62524 psi) or less - ◦ - - -
Difference between the WSC oil pressure command value and the oil pressure sensor value is 235 kPa (2.4 kgf/cm2 , 34 psi) or higher - - ◦ - -
Oil pressure sensor value is higher than the line pressure command value by 490 kPa (5.0 kgf/cm2 , 71 psi) or higher - - - ◦ ◦
Duration - - 3 times for 0.5 seconds or more 3 times for 1 second or more 3 times for 1 second or more
Detection Logic 2-trip detection logic 2-trip detection logic 2-trip detection logic 2-trip detection logic 2-trip detection logic

HINT: 

This DTC is stored when any of the above detection patterns are met.

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