5.9L Cummins Diesel engine block heater cord. What does a block heater do? The block heater warms the engine coolant and oil, providing easier starting in low temperatures. On 2003-2007 Dodge trucks the heater element is already installed in the block; you just need to remove the cap and plug in the extension cord.
The plug is located on the passenger side, by the turbocharger. The most common way of routing the cord would be from the element leading out through the vehicle’s grille. When routing cord be sure not to place cord by any moving or hot parts, using zip-ties to fasten securely.