2016 F-450 Incorrect Outside Temperature Indication

mchan68 · October 30, 2016

I have an appointment coming this week for a 2016 F-450 reading incorrect outside temperature on the instrument cluster message display. This vehicle came in last week, with the outside temperature reading -35C. Obviously incorrect. I know the ambient temperature sensor is located on the underside of the passenger mirror, so I took a lighter to it, to see if the reading would change. It did not. Apparently, the reading has gone way off according to the customer so he'll be coming in this week to address it. I have searched Section 413-01 high and low, and I can't find anywhere where the message display obtains the outside temperature reading from, let alone how to diagnose and address this concern. If it matters, the vehicle is an XLT trim level (so low end message center display), 6.7L 4x4 CCLB.

tonybullitt · October 31, 2016

It is in 413-01

The outside air temperature display is inoperative/incorrect

Communication concern

PCM concern

GO to Pinpoint Test AS.

tonybullitt · October 31, 2016

Normal Operation

The ambient air temperature sensor is hardwired to the PCM through separate input and return circuits. The PCM provides a reference voltage to the ambient air temperature sensor and monitors the change in voltage resulting from changes in resistance as determined by outside air temperature. The PCM messages the raw ambient air temperature data to the HVAC module through the Body Control Module (BCM) . The HVAC module then filters the data and sends the modified ambient temperature data to the Instrument Panel Cluster (IPC) through the BCM in degrees Celsius (metric). When the Fahrenheit (English) display is selected by the driver, the IPC converts the Celsius to Fahrenheit and displays the temperature in the message center. The outside air temperature value can be reset by using a HVAC multiple button press procedure. The reset procedure enables the raw data from the ambient air temperature sensor to be displayed in the message center bypassing the interpretation process carried out by the HVAC module. After the outside air temperature reset has been carried out, the system begins updating through the normal interpretation and update procedure.