ZF 4HP 16 - Automatic Transmission (European and N. American Emissions)

DTC P1881 (European and N. American Emissions)

Circuit Description

The 4HP 16 Auto Transaxle operates without freewheels. Shifting between individual gears takes place by means of overlapping clutch engagement and release.

The advantages of overlap shifting include the following features:

* The transaxle can be more compactly designed and lighter because of the absence of freewheels and the lower number of shift elements.
* Lower drag losses, resulting in higher efficiency
* Lower peak torque acting on the components and the driveline

However, overlap shifting requires high-performance hardware and software and precision engine signals.

Conditions for Setting the DTC

* The transmission oil temperature is greater than -10°C (+14°F).
* The selector lever is not in Neutral or Park position.
* System voltage is greater than 9 volts.
* No input speed error DTCs P0715, P0716, or P0717.
* Output speed is greater than 256 RPM.
* Input speed is greater than 400 RPM.
* The 2-1 gear shift is active.
* Immediately after the above condition occurs

Action Taken When the DTC Sets

* The malfunction indicator lamp (MIL) will illuminate.
* The transmission control module (TCM) will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer.
* Adopt Emergency/Substitute mode and constant 3rd gear.
* Open 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

When DTC P1881 sets, the possible cause of fault could be TCM.