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

DTC P0781 (Non-European or N. American Emissions)

Circuit Description

The special feature of 4HP 16 Auto Transaxle is that the transaxle operates without freewheels.

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

The advantages of overlap shifting are as follows:

* The transaxle can be of more compact design and is lighter because of the absence of freewheels and the lower number of shift elements.
* Lower drag losses, such as higher efficiency
* Lower peak torque acting on the components and the driveline

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

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

* The hold lamp will blink.
* 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 1st gear.
* Open lock up clutch

Conditions for Clearing the Hold Lamp/DTC

* The hold lamp 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 P0781 sets, the possible cause of fault could be the TCM.