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.
Electronic Automatic Temperature Control Module - Diagnostic Methods
The electronic automatic temperature control system must be diagnosed by first retrieving any DTCs, if present.
- An on-demand (hard fault) DTC indicates that the fault is currently present. An on-demand DTC suggests a wiring fault, disconnected connector, or component failure.
- A continuous (intermittent) DTC alone (corresponding on-demand DTC is not present) indicates that the fault is an intermittent condition and may not be currently present. A continuous only DTC suggests a poor wiring connection, loose pin or terminal, or intermittent component failure.
On-demand (hard fault) or continuous (intermittent fault) DTCs can be retrieved using a diagnostic tool. If using a diagnostic tool, refer to the diagnostic tool operating manual.
On-demand DTCs can also be retrieved by carrying out the Electronic Automatic Temperature Control Module Self-Test. To retrieve and/or clear continuous DTCs carry out the Electronic Automatic Temperature Control Module - Retrieve Continuous DTCs procedure. Always carry out the Electronic Automatic Temperature Control Module Self-Test before retrieving continuous DTCs.
If no DTCs are present, GO to SYMPTOM CHART for the appropriate diagnostic action.
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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.