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

DTC P1606 (European and N. American Emissions)

Circuit Description

The external watchdog will be triggered. If the external watchdog does not run out after 30 ms then the fault will be detected.

Conditions for Setting the DTC

* System voltage is too high or too low.
* Transaxle input voltage is too high or too low.
* 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 4th gear by hydraulic control.
* After ignition OFF/ON : 3rd gear by hydraulic control. P, R and N also possible.
* Power supply cut off to the pressure control solenoid (PCS) valve.

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 P1606 sets, the possible cause of fault could be the TCM.