ZF 4HP 16 - Automatic Transmission (North American Emissions)

DTC P1791 (North American Emissions)

Circuit Description

The transmission control module (TCM) is an electronic device that monitors inputs to control various transaxle functions, including shift quality and transaxle sensors, switches, and components to process for use within its control program. Based on this input information, the TCM controls various transaxle output functions and devices.

The following information transmits between the TCM and the engine control module (ECM) through the controller area network (CAN). The information is as follows:

* The engine malfunction signal
* The engine speed
* The engine output torque reduction signal
* The engine coolant temperature

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1791 Throttle/Pedal Position Signal

Conditions for Setting the DTC

* The system voltage is too high or too low.
* The TCM or ECM is defective.

Action Taken When the DTC Sets

* No lamp control is required, but diagnostic information should be stored immediately when the malfunction is detected.
* Adjustable value, calculated over the substitute map throttle position, such as engine speed or engine torque

Conditions for Clearing the DTC

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.