Skip to content

1.3.3 BODY PDU

Bussmann LR-2 BODY PDU

Type: Military-Spec Relay/Circuit Breaker Panel

Model: Bussmann LR-2

Part Number: 301-1C-C-R1 (NSN: 6110-01-523-6374)

Manufacturer: Bussmann (Eaton)

Source: Military surplus (MRAP/LMTV truck)

eBay Listing: Bussmann LR-2 Relay Breaker Block

Mounting: Firewall - body side (cabin), passenger side

Power Source: CONSTANT power from AUX battery via 2 AWG feed

Ground: Firewall Stud Bus Terminal 3 (14 AWG) - relay coil/logic reference only

Configuration: 8 circuit breaker positions + 8 relay positions

Input: Military-spec power studs (accepts up to 2 AWG wire)

Output: J301-J306 Metri-Pack connectors (military-spec sealed)

Protection: IP65+ sealed military-grade enclosure

Temperature Rating: Military spec (-40°F to 221°F typical)

Voltage: 12V DC (originally 12V/24V dual voltage)

Circuit Breaker Configuration

CB Position Original Military Label Repurposed Circuit Size Gauge Load Relay Notes
CB30 CHEM DETECT Fusion Head Unit 15A 14AWG ~15A - CONSTANT power, ignition sense from bus bar
CB48 ARCT CRAN USB Charging Ports 20A 14AWG ~13A - 2x Powerwerx PanelUSB-75W (78W each, 7.5A fuse ea)
CB39 TRLR BO STOP WolfBox Camera/Mirror 10A 16AWG ~10A - Dash cam + backup camera
CB45 IGNITION Driver Heated Seat 15A 14AWG 5A peak, 2A sustained K21 Manual switch → relay K21 → seat element
CB42 2WAY INTRCM Passenger Heated Seat 20A 14AWG 5A peak, 2A sustained K22 Manual switch → relay K22 → seat element
CB20 RADIO Cargo Lights 10A 16AWG 4A - Switch on wheel well top
CB43 TRANS ECU Winch Control (dash rocker) 10A 18AWG ~2A - Dash rocker + remote parallel control
CB44 TRLR LIGHT [Available] - - - - Future expansion

Circuit Breaker Utilization: 7 of 8 used (1 available)

Relay Configuration

Relay Position Original Military Label Repurposed Function Voltage Control Notes
K21 REAR LEFT LIGHT Driver Heated Seat 12V Dash switch Controls CB45 output to driver seat
K22 REAR RIGHT LIGHT Passenger Heated Seat 12V Dash switch Controls CB42 output to passenger seat
K27 TRAILER BO STOP [Available] 12V - Future expansion
K30 TRAILER REAR LEFT [Available] 12V - Future expansion
K31 TRAILER REAR RIGHT [Available] 12V - Future expansion
K53 RADIO [Available] 24V→12V - Replace with 12V relay
K40 START DISABEL [Available] 24V→12V - Replace with 12V relay
K42 ENGINE PTO [Available] 24V→12V - Replace with 12V relay

Relay Utilization: 2 of 8 used, 6 available (3 require 12V relay replacement)

Total Load: ~60A maximum (Radio 15A + USB 13A + Camera 10A + Seats 10A peak + Winch control 2A + Cargo lights 4A)

Control: All circuits on CONSTANT power with trigger-wire or manual switch control for on/off

Communication Devices

G1 GMRS Radio, STX Intercom, and Ham Radio are powered from SafetyHub 150 (START battery) as critical infrastructure, with direct grounds to START battery to minimize RF noise.

Outstanding Items

  • Identify pinout for J301-J306 Metri-Pack connectors (military TM manual or reverse engineering)
  • Determine replacement 12V relay part numbers for K40, K42, K53 (currently 24V coils)

Design Notes:

  • High-side switching: BODY PDU switches positive power to loads; load current returns through each load's own ground wire, NOT through the PDU. The PDU ground connection (~3A) is only for relay coils and internal logic.
  • Heated seat current: 5A peak, 2A sustained per seat (verified with vendor)
  • Military relays K21/K22 provide fault isolation and independent operation
  • J301-J306 connectors require custom harness fabrication