“What is the alternator regulator?”
On modern Fiat diesels it’s not a simple old-style regulator anymore.
Your 500X uses an intelligent alternator regulator that’s LIN-controlled by the ECU. Instead of charging constantly, the ECU tells it when and how hard to charge (for emissions, Start/Stop and fuel economy reasons).
In practice, this system causes far more trouble than it saves - and when it starts failing intermittently, you get exactly the kind of random electrical faults you’re seeing now.
The regulator itself is often a separate part bolted to the alternator, not the whole alternator.
So don’t rush into buying a full alternator yet - very often it’s just the smart regulator module or its LIN control circuit that fails. On these cars, intermittent IAM faults (P065A), voltage dips, random EPB/glow plug/clutch sensor faults are classic symptoms of a regulator or control-line problem.
Running the IAM reset in
MES is absolutely the right first step. If it improves things temporarily, that strongly points to a failing intelligent regulator. Because your problem is intermittent, a bench alternator tester may not catch it. The best real-world test is to monitor voltage under load, watch commanded vs actual alternator voltage in
MES and see if P065A returns. If it does, the regulator or its LIN wiring is the root cause, not the clutch sensor, glow plug, or battery.
