I'm started experiencing the same symptoms with my truck. First 100k was fine - gauge never moved north of the 200 mark. Now when pulling hills it will creep past the second 0 but then cool right back down after cresting the grade. Using my Smarty, I noticed I had triggered the fan clutch code so replaced my fan clutch but still not helping and still do not hear my fan engage. Yet, I'm not getting the code anymore. So... new fan clutch, no code, fan still not engaging, and temperature continuing to creep past the second 0. One thing that helped was using the timing option on my Smarty. It appears the advanced timing has improved my engine temps but not addressed the root cause.
I've changed my anti-freeze every 50k and used distilled water so I'm doubtful it is the radiator. I'm thinking my issue is with the TIPM or ECU. Since I don't have the diagnostic tool, I may need to take to the dealer to troubleshoot
I've changed my anti-freeze every 50k and used distilled water so I'm doubtful it is the radiator. I'm thinking my issue is with the TIPM or ECU. Since I don't have the diagnostic tool, I may need to take to the dealer to troubleshoot

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