An optional engine block heater is available in the Grand Cherokee (standard equipment in Canada). The heater is equipped with a power cord. The cord is attached to an engine compartment component with tie-straps. The heater warms the engine providing easier engine starting and faster warm-up in low temperatures. The heater elements are not immersed in engine coolant, they make direct contact with the block.

The 3.6L engine block heater is located on the driver side toward the front of the engine. The block heaters for the 5.7L and 6.4L engines are located on the driver side below the exhaust manifold at the rear of the engine.

Connecting the power cord to a grounded 110-120 volt AC electrical outlet with a grounded, three wire extension cord activates the heating element warming the engine coolant.

If the unit does not operate, possible causes can be either the power cord or the heater element. Test the power cord for continuity with a 110-volt voltmeter or 110-volt test light. Test heater element continuity with an ohmmeter or a 12-volt test light.

1. Mopar engine block heater kits for 2011-2015 3.6L and 5.7L engines

Engine Block Heaters keep the engine warm for easier starting and quicker warm-up. Features include special plug-in wiring designed for each application and is the same as the production heaters. Depending on engine size, the heaters consume 450 to 600 Watts.

Engine Block Heater Kit - 3.6L V6.   Mopar p/n 82212440.  MSRP $76.55

Engine Block Heater Kit - 5.7L V8.   Mopar p/n 82212439.  MSRP $84.50

Installation Instructions (PDF)

3.6L Engine Block Heater Installation

5.7L Engine Block Heater Installation

2. Engine block heater - 3.0L CRD diesel models

For U.S.A. models, the engine block heater element is pre-installed into all 3.0L engines. On vehicles where the engine block heater option was not purchased when the vehicle was originally ordered, only the heater cord itself needs to be purchased and installed. In some markets, such as Canada, both the engine block heater and cord is standard equipment.

Engine Block Heater cord, 3.0L Diesel.   Mopar p/n 68186526AB.  MSRP $67.25

From smithcu4 on the JeepGarage forums:
Install from the top. I squeezed my arms down the backside of the engine compartment (literally against the firewall to the cabin of the vehicle) on the passenger side and then reached forward until I felt a very malleable rubber. Pull, and you have just found the infamous orange plug. I then ran the cord straight down vs going through the back part of the engine compartment.

I had trouble getting the leverage needed to push the plug in with my left arm, so I took the engine cover off and put down several thick blankets, laid across the engine, and put my right arm down the back of the engine compartment - success. Zip tie and then figure out what you are going to do for an extension, b/c unless you want to leave it flopping around from under the hood, you'll need one.