Alfa 156 Dead: Key Turn Issue Points to Ignition System

Based on some experience working on Alfa Romeos, I had a very similar issue with my Alfa 155 2.5 TD from around the same era. The symptoms were identical, complete electrical silence when turning the key. After checking the obvious things like the battery terminal connections and main fuses, my mechanic performed a thorough diagnostic of the ignition switch and wiring harness. The root cause turned out to be corroded connections in the main relay switch assembly that feeds power to the ignition circuit. The repair involved cleaning and refitting several connections in the wiring harness, plus replacing one damaged relay switch. Total cost was 95 Euro including parts and labor. The car has worked flawlessly since then. To help troubleshoot your specific case, could you share: Exact build year of your 156, Whether any electrical issues preceded this complete failure, If you notice any intermittent function before total failure, Whether the central locking still works normally The power supply routing is quite similar between these models, but there are some variations that could affect the diagnostic approach. Once you provide those details, I can share more specific insights about which components to check first.

Last service check was at 75000 KM, so pretty recent. After trying several steps, I discovered the starter solenoid was completely dead. Got the mechanic to do a full voltage drop test and all connections through the wiring harness were intact. The power supply routing checked out fine too. The issue was indeed with the starter solenoid, it had corroded internally and needed replacement. Fixed it for 180 Euro with installation. Would recommend others facing a car that wont start to specifically check the starter solenoid first if they have similar symptoms. Since the repair, all electrical systems are working normally again with no voltage drops or connection issues. Really appreciate everyone who chimed in with suggestions.

Thanks for the update on your Alfa 156. I had actually suspected the starter solenoid might be the culprit after you mentioned the complete silence when turning the key, since my 155 had shown similar symptoms in the past. The starter solenoid failure is indeed a common issue in these models, though mine initially misled me toward thinking it was the wiring harness or relay connections. Your repair cost of 180 Euro seems reasonable considering the labor involved in accessing and replacing the component. Just to share a preventive tip from my experience: periodic checks of the starter solenoid connections can help catch corrosion early. When a car wont start and shows these symptoms, checking the solenoid should definitely be high on the diagnostic checklist, right after basic battery and fuse box inspection. Glad to hear everything is working properly now. These older Alfas can be tricky with electrical issues, but they are quite reliable once the right component is identified and fixed.

Thanks everyone for the help with diagnosing my 156's starting issue. Just wanted to close the loop on what fixed it. The starter solenoid turned out to be completely dead. Had the mechanic do a full check of the wiring harness and power supply routing which were both fine. The fuse box and relay switch connections were also intact. The starter solenoid had corroded internally and needed complete replacement. Total repair cost was 180 Euro including installation. Car starts perfectly now with no electrical issues. For others facing similar symptoms, total silence when turning ignition switch with good battery, definitely get the starter solenoid checked first. Could save time in diagnosis since the wiring can look fine even when the solenoid is bad. All systems working great now with no voltage drops or connection problems. Appreciate the advice that helped narrow down the issue.