Junction Block: Description: Description

2009 Jeep Commander Overland, 4WDSECTION Description
Fig 1: Identifying Steering Column Lower Cover & Steering Column Opening Cover
GC0118621Courtesy of CHRYSLER LLC

An electrical Junction Block (JB) is concealed beneath the driver side of the instrument panel in the passenger compartment of the vehicle. The JB is accessed by pulling down on the steering column opening cover (2) exposing the lower steering column and portions of the instrument panel wiring harness. The JB combines the functions previously provided by a separate fuseblock module and relay center. The JB serves to simplify and centralize numerous electrical components, as well as to distribute electrical current to many of the accessory systems in the vehicle. It also eliminates the need for numerous splice connections. The JB houses blade-type mini fuses, blade-type automatic resetting circuit breakers and International Standards Organization (ISO) relays.

Fig 2: Identifying Harness Connectors
GC0118622Courtesy of CHRYSLER LLC

The molded plastic JB housing is secured with four screws and two snap retainers to the JB mounting bracket behind the instrument panel steering column opening cover (3). The steering column opening cover can be pulled downward to disengage the latches and provide service access to all of the fuses, relays and wire harness connectors (1) of the JB. Refer to Steering Column Opening Cover  in Body for additional service information.

The JB contains six relays that are integral to the housing assembly. The relays cannot be replaced separately. If any of the relays are diagnosed inoperative or damaged the complete JB unit must be replaced. The six relays are:

  • Lock relay
  • Unlock relay
  • Driver door unlock relay
  • Rear wiper relay
  • Ignition "RUN" relay
  • Ignition "RUN/ACCESSORY DELAY" relay

The JB unit cannot be repaired and is only serviced as an assembly. If any internal circuit or the JB housing is inoperative or damaged, the entire JB unit must be replaced. See Removal  for the appropriate procedure.

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