Pacifica Hybrid ECU Issues Causing Power Loss & Errors

Had similar issues with a Chrysler 300e Hybrid from a close model year. The symptoms matched exactly, power loss, engine control system warnings, and inconsistent performance. Initially thought it was the ECU, but diagnostic testing revealed a failing main relay in the control system. The main relay acts as a critical gateway between the computer module and engine components. When it deteriorates, it causes intermittent electrical supply to the ECU, making the system behave erratically. The repair required removing multiple components to access the relay assembly and perform a complete system reset after replacement. This was a serious issue that needed immediate attention since a failing main relay can eventually lead to complete engine shutdown. The diagnostic process took several hours because intermittent electrical issues can be tricky to pinpoint. Based on the symptoms described, strongly recommend getting a specialized diagnostic test focusing on the main relay and surrounding control system components before assuming ECU failure. Many shops misdiagnose this because the symptoms mimic a bad ECU. The testing should include voltage measurements at the relay points while the engine is running.

Thanks for sharing your experience with the main relay issue. The symptoms you described sound exactly like what I am experiencing. Just took my Pacifica to another shop yesterday for car diagnostics and they also mentioned checking the relay system before jumping to ECU repair conclusions. Did you remember roughly how much the complete repair ended up costing? Also, have you experienced any similar vehicle electronics issues since getting it fixed? Really hoping to avoid replacing the entire engine control unit if possible.

Just wanted to follow up, got the main relay replaced last week and the engine performance issues completely cleared up. Total cost was 120€ for parts and labor, which was way better than potentially replacing the entire ECU. The vehicle electronics and computer module are now working perfectly. No more error messages or power loss issues. The mechanic confirmed the ECU itself was actually fine, it was just getting inconsistent power due to the faulty relay. Been driving for about a week now and the engine control system is running smooth with no recurring problems. Definitely worth getting that second opinion rather than jumping straight to an ECU replacement. The diagnostic approach saved both time and money by identifying the actual relay issue.

Thanks everyone for the great advice! Wanted to share how this ended for me. Took the car to a shop specializing in automotive electronics and they diagnosed the exact same relay problem mentioned here. The repair cost came to 180€ including diagnostics and labor. The mechanic showed me the old relay which had visible burn marks on the contacts. After replacing it and running a system reset, the engine control issues disappeared completely. The car now runs like new, no more sluggish performance or error messages from the computer module. Really glad I got that second opinion instead of replacing the whole ECU. Total repair time was about 3 hours and I was back on the road the same day. For anyone facing similar symptoms, definitely have the control system relay checked first. Much simpler fix than a full ECU repair and solved all the problems.