ZF 4HP 16 - Automatic Transmission

DTC P0742

Circuit Description

Shifting between individual gears takes place by means of overlapping clutch engagement and release.

If 2 clutches are engaged or released at the same time during shifting, the transaxle or engine could be damaged.

To prevent this damage, the transmission control module (TCM) monitors the clutch pressure at the shifting point.

Once shifting begins, the TCM begins the monitoring after the regular time and inspects the turbine revolution speed. If the revolution speed is not within the specified value, the fault occurs and the TCM memorizes it.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0742 Torque Converter Clutch (TCC) System - Stuck On

Conditions for Setting the DTC

* The vehicle shift solenoid fault does not occur.
* The throttle is more than 25 percent.
* The transmission oil temperature is more than -10°C (+14°F).
* The system voltage is more than 9 volts.
* No input speed error DTCs P0715, P0716, and P0727 are set.
* No engine speed error DTCs P0725, P0726, and P0727 are set.
* The engine speed is more than 1,200 RPM.
* The input speed is more than 1,200 RPM and 3,500 RPM.
* The engine is running.
* The selector lever is not in the Neutral (N) or Park (P) position.
* The torque converter clutch (TCC) lock-up status is commanded OFF.

Action Taken When the DTC Sets

* The malfunction indicator lamp (MIL) will illuminate.
* The TCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer.
* Open the lock-up clutch.

Conditions for Clearing the MIL/DTC

* The MIL will turn OFF when the malfunction has not occurred after 3 ignition cycles.
* A history DTC will clear after 40 consecutive warm-up cycles without a fault.
* Using a scan tool can clear history DTCs.

Diagnostic Aids

* Inspect the poor wiring harness connection for TCM connectors and transaxle wiring connectors.
* Inspect the improperly formed or damaged terminals.