What does it mean?
P1887 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: TCC Release Switch Circuit Malfunction (4T65-E) .
Symptoms
- Malfunction indicator lamp on with a converter clutch related code
- Engine stumbles or stalls when coming to a stop, as if the clutch stays applied
- Shudder or vibration at light throttle just below lockup speed
- Harsh converter clutch apply and release
- Poor fuel economy and higher transmission fluid temperature
- Default (limp) operation on some vehicles
Likely causes
- Failed TCC release pressure switch with worn or stuck contacts
- Open or short in the switch circuit between the transmission and the module
- Fluid intrusion or corrosion at the transmission case connector
- Damaged internal harness inside the transmission
- Low line pressure or a stuck TCC regulator valve so the clutch never fully releases
- Contaminated fluid holding the valve body spool
- Faulty input circuit in the TCM/PCM
How to fix it
- Check fluid level and condition first — low or burnt fluid changes converter clutch behaviour
- Watch the TCC release switch state in live data with the converter commanded on and off
- Inspect the transmission case connector for fluid, corrosion and terminal condition
- Measure the switch circuit for continuity, short to ground and short to voltage
- Command the torque converter clutch with a bidirectional tool and confirm rpm drops and returns as expected
- If the electrical side is good, inspect the valve body for a stuck TCC regulator valve
- Replace the pressure switch or the valve body assembly, then verify with a road test