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

DTC P1854 (European and N. American Emissions)

Circuit Description

The shift solenoids are two identical, normally open electronic exhaust valves that control upshifts and downshifts in all forward gear ranges. These shift solenoids work together in a combination of ON and OFF sequences to control the line pressure and shift mechanisms, such as clutches and brakes.

Solenoid 2 controls the high or low of the line pressure - the flow to each clutch valve - by the operation type ON/OFF. For example, solenoid 2 is ON, line pressure will be low (599-799 kPa) (87-116 psi) (6-8 bar); solenoid 1 is OFF, line pressure will be high (1599-1799 kPa) (232-261 psi) (16-18 bar). Solenoid 2 controls the oil flow to clutch valve E or lock-up clutch valve by the ON/OFF signal.

The transmission control module (TCM) monitors numerous inputs to determine the appropriate solenoid state combination and transaxle gear tor the vehicle operating conditions.

Conditions for Setting the DTC

* Solenoid wiring shorted to power.

* No DTC P1853, P1855.

* Immediately after the above condition occurs.

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.

* Adopt Emergency/ Substitute mode and constant 4th gear.

Conditions for Clearing the MIL/DTC

* The MIL will turn OFF when the malfunction has not occurred after three-ignition cycle.

* 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 P1854 sets, the possible cause of the fault could be solenoid 2.