Normal Operation

WARNING: This page is about a different car, the 2014 Lincoln MKX and 2014 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.

When the Intelligent Access (IA) key is activated by one of the low frequency passive start antennas, the transmitter in the IA key sends a radio signal to the Tire Pressure Monitor (TPM) module. The TPM module then communicates the command to the Remote Function Actuator (RFA) module, and the RFA either switches the ignition to the requested mode or starts the engine.

The TPM module receives voltage at all times and has a dedicated ground circuit. The TPM module sends Tire Pressure Monitoring System (TPMS) information over the Medium Speed Controller Area Network (MS-CAN) to the Body Control Module (BCM). The TPM module sends all Remote Keyless Entry (RKE) and IA key information and requests to the RFA module through a dedicated single circuit network.

In the event of a failure with the TPM module, the vehicle experiences a no-start unless the IA key is placed in the backup slot.

DTC U201F:31 (External Receiver: No Signal) - an on-demand DTC that sets when the RFA module has lost communication with the TPM module.

This pinpoint test is intended to diagnose the following:

Wiring, terminals or connectors
TPM module
RFA module