$24 (P1784) - L-R Pressure Switch Circuit

Name of code: $24 (P1784) - L-R Pressure Switch Circuit

When monitored: Whenever the engine is running.

Set condition: This code is set if the L-R pressure switch is either open or closed at the wrong time in a given gear.

Theory of operation: The Transmission system uses three pressure switches to monitor the fluid pressure in the L-R, 2-4, and OD elements. The pressure switches are continuously monitored for the correct states in each gear as shown below.





Transmission Effects: If a set condition is identified, 1st gear and torque converter lock-up (EMCC) will be inhibited. The vehicle will launch in 2nd gear and shift normally through the gears without allowing EMCC. The MIL will illuminate after 5 minutes of substituted gear operation. If during the same key start, the set condition is no longer valid, the transmission will return to normal operation (1st and EMCC available). If a code 28 is set along with the code 24, the MIL will illuminate and the transmission system will go into relay open limp-in mode immediately.

Possible causes:
- If code 35(P1791) is present, ignore code 24(P1784) and perform code 35(P1791) diagnostic procedures
- L-R pressure switch sense circuit open or shorted to ground between TCM and solenoid pack
- L-R pressure switch sense circuit shorted to battery
- Solenoid pack defective
- Valve body - solenoid switch valve stuck. (May be accompanied by a code 37(P1775))
- Loose valve body bolts
- Plugged filter - internal transmission or torque converter failure
- Defective TCM