Torq Conv Clu, No RPM Drop At Lockup (OBD II)

Name of Code:
148 ($94) - Torque Converter Clutch (TCC) System Malfunction

When Monitored:
Continuously with the key on.

Set Condition:
If the TCC cannot achieve the desired drop in engine RPM when the TCC solenoid is near maximum duty cycle. Three consecutive bad tests are required to set the code.

Theory of Operation:
The TCC connects the engine crankshaft to the transmission input shaft when the TCC solenoid is at 100% duty cycle. When the PCM initiates the TCC engagement, the TCC solenoid duty cycle starts out low and increases until the TCC is fully engaged. The TCC will only engage in 3rd and 4th(OD) gears. The PCM will not allow TCC engagement when the transmission oil temp is below 32 Degrees F.

Transmission effects:
No TCC. The MIL may or may not illuminate depending on the PCM calibration.

Possible Causes:
- Drive wheel size is bigger than standard wheel size or smaller than spare. (3 spd only)
- TCC Solenoid failure
- Sticky Converter Clutch valve
- Sticky Converter Clutch Timing valve
- Internal transmission leakage
- Check Input Shaft, Reaction Shaft, and Seal Rings
- Valve body leakage
- Faulty Torque Converter
- Internal controller failure (PCM)