i have a l9000 tri axle dump truck with a cat 350 hp 3406 engine model...once the engine reaches operating temperature(190-200F) i have "red stop engine light comming on follow by "yellow warning light" right after a few seconds.they both stay on for about 1 minute then red light goes out first folow by yellow light. it does that every 5 minutes on the hyw.last yr it used to do it every hr.so it`s getting worse. i`m afraid driving on the hyw. i may have to tow the truck back to my yard at a huge expense.i checked all fluids are at max level and the engine has a so called e.c.m.(engine control module).any possible cause or problem?do i need to do a scan test of the engine?i `ve read here maybe i need to change my coolant filter (3 yrs old)?any help would be greatly appreciated....thank you all in advance and the forum,victor.
Welcome to the forum! I am not much of a mechanic and others on here will be able to help more, but your operating temp seems to be in the correct range so I believe I would want to verify the temp gauge is correct first. If you have a 3406B then the engine is completely mechanical, but a 3406C PEEC is when Cat started to go to electronic controls. If you have an ECM then you would have a C, and I suspect that the likelyhood of your problem is in the ECM rather than the actual temperature being hot. Also, it is possible that the wrong temp sensor for the warning light has been installed; ie. if you have a 200 degree temp sensor (not the guage sensor but the one that triggers the warning light) then it would likely come on and off according to thermostat opening and coolant temp minor fluctuations. I had a similar problem with an older truck (3406B) that had had the wrong high temp sensor installed before I bought it. I hope that your problem is as simple as that because it was easy and inexpensive to fix. Again, welcome to the forum and other members much more knowledgeable than I will be able to help you!