Medium and Heavy Trucks
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Hi my name is***** you getting any fault codes? Sounds like a possible wiring harness issue or ECU software issue. Let me know what you have for codes. Plugging ingo the ECU with the scan tool that reads live data will let you monitor switch status, etc. and help narrow down a wiring or ECU problem. If it points to ECU i'd try reprogramming before replacement as it could be a software glitch. Let me know
Unfortunately not. What is the engine model and serial number from the ID tag. I will check to see if I have an ECU schematic to help.