The torque converter enable solenoid activates the TCC valve which controls the pressurized hydraulic fluid that actuates the torque converter lockup clutch. If it does not work properly, the torque converter clutch will not be able to connect the engine and transmission into a 1:1 direct drive, reducing the engine’s performance and efficiency. It may also cause the engine to stall, if the lockup clutch cannot release when it is commanded to. This condition will prompt a P1864 diagnostic trouble code.
How Serious is the Code?
A P1864 DTC is extremely serious, because it can affect the overall drivability of the vehicle. Should the torque converter clutch failed to operate properly, the engine may not be able to shift on command and the engine may also stall unexpectedly. Needless to say, this pose a serious safety hazard. In addition, maximum line pressure may be commanded, which can severely damage internal components.
Symptoms of a P1864 include:
- Delayed shifts
- Torque converter lockup function does not engage
- No fourth gear
- Engine stalling
- Poor engine performance
- Dirty transmission fluid.
- A bent or broken terminal inside of a connector
- Damaged wiring
- Faulty torque converter enable solenoid
How to Diagnose the Code?
The transmission fluid may contain sludge and metal fragments, which can affect the operation of the torque converter enable solenoid. So obviously, this should be checked first. If no issues are found, the wiring and connectors should be inspected for signs of damage or corrosion. If everything looks good up to this point, then the torque converter enable solenoid should be tested.
What Repairs Will Fix P1864?
- Service the transmission (i.e. change the transmission fluid)
- Repair or replace damaged wiring/connectors
- Replace torque converter enable solenoid
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