Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Ambient Temperature Sensor
The ambient air temperature is monitored by the PCM (gas) FCM (diesel) and displayed by the CT/CMTC/EVIC. The PCM (gas) FCM (diesel) receives a hardwire input from the ambient temperature sensor (ATS).
The ATS is a variable resistor that operates on a 5-volt reference signal circuit hardwired from the PCM (gas) FCM (diesel). The resistance in the ATS changes as the outside temperature rises or falls. The PCM (gas) FCM (diesel) senses the change in reference voltage through the ATS resistor. Based on the resistance of the ATS, the PCM (gas) FCM (diesel) is programmed to correspond to a specific temperature. The PCM (gas) FCM (diesel) stores and filters the ambient temperature data and transmits this data to the CMTC/EVIC via the PCI Bus. The ATS cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.