when I have a load on my 2007 chevy Durmacs. 6.6 And in a hard pull up hill. It goes in limp mode. Why?

 

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I would like to look into this further. Would you please PM me the last 8-digits of your VIN? Are you towing? How much weight?

Louis
GM Customer Service

 

7F130602. Yes I pull a 32 foot gooseneck trailer. Usaually about 10,000lb.
thanks g-money

 

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Thank you for providing the last 8-digits of your VIN. After researching your vehicle, I have not been able to find any known issues, as described, for 2007 Silverado 3500 vehicles.

Have there been any engine modifications?

Limp Mode occurs when the computer senses excessive slippage, or if the transmission loses communication with the TCM. In limp mode, no signal is sent to the shift solenoids, and the only forward gear available is Third. Reverse and Neutral are usable, but by only allowing one forward gear to move the truck.

I encourage you to consult with a certified technician for additional assistance. They will be able to offer a more accurate diagnosis after physically inspecting the vehicle.

Please keep me posted.

Louis
GM Customer Service