Wire harness with 4 sensors. 3 of the sensors that measure the battery temperature and one to measure temperature of cooling air. To check your existing sensors measure the resistance of the four sensors with the battery not hot. Al four should be the same. Use the 20k range on your ohm meter. Look at the wire colors to see how to insert in cable connector. Added Note:It is a good idea to check your hybrid battery cooling fan for dirt. If dirty clean it out and the battery because about 1/2 of the dirt you find in the fan is also in the cooling passages between the battery modules. The dirt is concentrated in the passages farthest from the fan and it only takes one passage to clog up with dirt to ruin your battery due to over-heating. The fan can be checked by pulling up the plastic tray that covers the battery. It is just held down with plastic rivets. Then pull the intake duct to the fan and look in side. Before you replace the plastic tray pull all plastic rivets stuck in the battery with a plastic rivet removing tool, a hammer claw, or two flat screw drivers. Slide the rivets back in place in the plastic tray and then snap it back in. The battery can be cleaned out by blowing down with a can of compressed gas and then using a long brush that is used to clean out the back coil of a refrigerator. The fan can be cleaned with a garden hose. Hold the motor high and the main vent toward the ground then spray the fan blades toward the opening. Let the fan sit with the motor high till the assembly dries.