Jeep Grand Cherokee HVAC Failure Traced to LIN Bus Communication Fault

In this 2022 Jeep Grand Cherokee, the AC system wouldn’t respond to any climate controIn this 2022 Jeep Grand Cherokee, the AC system wouldn’t respond to any climate control changes — stuck blowing through the defrost vents with no ability to change temperature. The touchscreen appeared to work, but the HVAC system did nothing.

During diagnostics, I found a communication fault on the LIN Bus (Local Interconnect Network) — a one-wire communication system used in modern vehicle submodules. Using OEM wiring diagrams and a PicoScope, I analyzed LIN waveform activity and identified a fault. The root cause? Watch and find out!

This case highlights just how critical it is to understand vehicle communication systems like LIN. I highly recommend John Thornton’s LIN Bus Operation and Diagnostics class, available through Automotive Seminars, for any techs looking to sharpen their network diagnostics.

Here is a sample of the class on Youtube
   • 2022 LIN Bus Case Study from John Thornton  

And the Full Class on Automotive Seminars
https://automotiveseminars.com/produc...

🛠️ Tools and supplies used in this video are available in my Amazon Shop:
https://www.amazon.com/shop/automotiv...

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