What does it mean?
P1768 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Automatic Transaxle Linear Solenoid Circuit Malfunction .
Symptoms
- MIL (check engine lamp) is on and the transaxle drops into limp mode with one fixed gear
- Shifts become either violently harsh or soft and flaring, because line pressure is no longer modulated
- Long delay before the vehicle moves after selecting drive or reverse
- Shift shock on downshifts and shudder from the torque converter under light load
- Transmission temperature warning on vehicles that display it
- Shift quality changes noticeably as the fluid warms up
Likely causes
- Linear solenoid coil open, shorted or with resistance drifting outside the specified window
- Varnish or fine metal debris in the solenoid bore restricting spool travel, so actual current never matches command
- Internal transaxle harness rubbed through against the case or valve body
- Corroded case connector after fluid or moisture has wicked into the pins
- Open circuit or short to ground on the wire between the control module and the solenoid
- Overheated, oxidised fluid changing solenoid response and reaction time
- Failed current-control driver in the control module
How to fix it
- Check the fluid level and condition; discoloured or burnt fluid points directly at internal wear
- In live data, compare the commanded solenoid current with the actual measured current across a road test
- Measure the solenoid resistance at the transaxle case connector against specification and test for a short to the case
- Check the module-to-solenoid wiring for opens and shorts, with a wiggle test at each connector
- Fit a pressure gauge and run a line pressure test in each range to prove whether the hydraulic response follows the command
- Replace the linear solenoid or the valve body when it is electrically or hydraulically out of specification, and renew the fluid and filter