The Totally Integrated Power Module (TIPM) is a lot more than the fuse box it appears to be. It is responsible for a lot of the power switching/modulation/distribution, and communications with other systems in the JK electrical system.
New TIPMs go for $200 - $250. Used can be found for $0 - $200; very negotiable. After replacing the TIPM, it may need to be programmed to the vehicle. As far as I know, only the dealer can do the programming.
This is from the factory service manual:
The original Cab Compartment Node and Powertrain Control Module must be installed and functioning properly prior to powering up the new TIPM. The TIPM receives vehicle configuration data from the CCN and Vehicle Identification Number information from the PCM. If configuration information becomes lost or corrupted, the data can be obtained from DealerCONNECT
I found a TIPM from a wreck, (the TIPM took a hit, too), so I salvaged the useable parts, and didn't mind disassembling it to see how it is made.
I couldn't find a detailed wiring diagram for the TIPM, so this is more a visual than technical presentation.
This is a view of the TIPM as it sits in the engine bay.
Looking down on the TIPM with the cover open. There is a diagram and legend on the inside of the cover. The square gray items are mechanical relays. The item labeled "Ignition Off Draw" is the one you pull up to minimize the drain on the battery if the vehicle will not be run for an extended time. (Up to 30 days. Longer than that, disconnect the battery, and charge it periodically.)
The item labeled "Occupant Restraint Controller" should not be relied upon to make safe the ballistic components of the system. All instructions say to disconnect the battery negative terminal and wait several minutes to make it safe.
Here is a view of a relay with the cover removed.
A view underneath the TIPM.
The bottom cover has been removed, exposing the TIPM circuit board. Also, the layers of connector prongs have been separated. The view is looking up from the bottom.
This view is from the top looking down. The fuses and relays have been removed, since with the separated layers, there are no connector prongs in the sockets to retain them. Notice how the prongs on each layer are connected, and that all the prongs stick through each of the layers above and below (previous photo, too).
All the layers, back together.
A good view of the "brain" of the TIPM. In addition to the IC's and such, there are mechanical relays in the 7 white components on the board. It is this portion of the TIPM that is not serviceable by the dealer or consumer.
Here are two views of the relays on the circuit board. The bigger ones are double relays, the smaller are single.
Here is my best effort to identify the relays on the circuit board.
The check mark by the name indicates I was able to verify what it controls by tracing the circuit, exclusively between relay and destination, with a continuity tester. On the rest of them there were too many common points among them to isolate each relay.
When each of the systems was energized, I could hear the click of a relay with the aid of a mechanic's stethoscope, (not one of the big relays in the fuse box section of the TIPM).
There was no click sound when the headlights and fog lights were turned on, indicating those are controlled with a solid state relay.