Sierra Cooling System Failure Linked to Control Module

Had a very similar wiring issue on my 02 Silverado last summer. Having some experience with electrical problems, I first suspected a faulty temperature sensor, but it turned out more complex. The communication fault between control modules was causing the cooling system to malfunction. After checking several components myself, I took it to a workshop where they traced it to a damaged wire harness connector near the engine control unit. The diagnostic trouble code pointed to a control module communication error, similar to yours. The root cause was a corroded plug connection that was interrupting the data flow between modules. The repair involved replacing the damaged connector and resealing the wiring. Total cost was 95 Euro and its been working perfectly since. Before suggesting specific solutions, could you share: Any recent work done on the electrical system? Does the overheating happen gradually or suddenly? Are there any other electrical issues like flickering gauges? Have you noticed the problem gets worse in wet conditions? These details would help determine if youre dealing with the same control unit connection problem I had.

Thank you for the detailed response. Just had my service at 141787 KM and appreciate you sharing your experience with the data link issues. I havent had any electrical work done recently, but the overheating occurs suddenly, especially during highway driving. The gauge cluster works fine with no flickering, and weather conditions dont seem to affect the problem. The CAN bus diagnostic at my last service showed intermittent communication errors. When the diagnostic trouble code scanner was connected, it revealed multiple control unit faults, which seems consistent with your connector issue. Will have the wiring harness inspected based on your feedback, as this definitely sounds like a similar pattern to what youre describing.

Thanks for those additional details. After reading about your specific symptoms, I'm even more convinced you're dealing with a similar CAN bus communication problem as I had with my Silverado. The sudden overheating during highway driving matches exactly what I experienced before finding the damaged connector. The control module wasn't receiving accurate temperature data, causing the cooling system to malfunction under higher loads. What's particularly telling is the multiple control unit faults showing up on your scan. In my case, the intermittent connection issues also triggered several fault codes because the data link was disrupted between modules. Since your gauge cluster is working normally, this narrows down the likely location of the wiring issue. The connection problem is probably closer to the engine control module rather than the instrument panel harness. I'd suggest having the shop focus on: The main engine control unit connector, CAN bus wiring near hot areas of the engine, Ground connections for the control modules, Harness routing points where wires might get pinched The repair should be relatively straightforward once they locate the exact connection point. My fix cost 95 Euro, though prices vary depending on which connector needs replacement.

Thanks for the excellent troubleshooting suggestions. After reading the details about your similar CAN bus communication problems, I'm feeling more confident about the repair direction. The car diagnostics showing multiple control unit faults during highway driving matches perfectly with what you experienced. Really helpful to know that your issue was tracked down to a specific connector, gives me a clear starting point with my mechanic. Going to have them inspect the wiring harness, particularly focusing on those connection points you mentioned near the engine control unit. Makes total sense that the diagnostic trouble code is pointing to communication issues if there's a damaged connector disrupting the data flow. Will get it into the shop this week and have them concentrate on the areas you suggested, especially the control module connections and ground points. Even if parts and labor run a bit more than your 95 Euro repair, having this focused troubleshooting approach should save time and money versus replacing unusual cooling system parts. Just wanted to circle back with appreciation for walking through the software glitch versus hardware problem possibilities. Your experience really helped narrow down where to look.