Fuse Box - Engine Bay

This procedure covers the removal and replacement of the engine bay fuse box (Integrated Power Module) on a 2007 Ram 3500 with the 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Integrated Power Module (IPM) fuse box × 1 — Use OEM Mopar specification
• IPM mounting bolts × 3 — Reuse unless damaged
• Wire harness connector seals × 1 — Inspect and replace if damaged

Preparation

1. Park vehicle on level ground and set parking brake
2. Turn ignition to OFF position and remove key
3. Open hood and secure with prop rod
4. Locate both batteries under the hood (passenger side)
5. Photograph or label the fuse box cover diagram for fuse/relay positions
6. Take photos of all wire harness connections to the IPM from multiple angles

Procedure

1. 1

   Disconnect battery negative terminals
   Using a 13mm socket, disconnect the negative terminal from both batteries. Both batteries are located on the passenger side; disconnect the negative terminal from the primary battery first, then disconnect the negative terminal from the secondary battery. Wait at least 2 minutes for capacitors in the electrical system to discharge.
   ⚠️Both batteries must be disconnected. Disconnecting only one battery will not fully de-energize the system.
2. 2

   Remove fuse box cover and document fuse locations
   Release the tabs on the Integrated Power Module cover and remove it. If not already photographed, document all fuse and relay positions. Remove all fuses and relays, placing them in a labeled container or tray matching their original positions.
3. 3

   Disconnect main wire harness connectors
   Locate the large wire harness connectors on the bottom and sides of the IPM. There are typically 3-4 large multi-pin connectors. Press the locking tab on each connector while pulling straight away from the IPM. Use needle-nose pliers to release stubborn locking tabs. Do not twist or rock connectors excessively.
   ⚠The red locking tabs must be lifted or pressed (depending on connector type) before the connector can be removed. Forcing will break the tabs.
4. 4

   Remove air intake components if necessary
   For better access, loosen the hose clamp on the air intake tube at the turbocharger inlet and remove the air intake tube. This provides additional clearance for removing the IPM. Set aside the intake components in a clean area.
5. 5

   Remove IPM mounting fasteners
   Locate the mounting bolts securing the IPM to the fender well and inner structure (verify count and head size against the OEM service manual). Remove all bolts completely and retain them if in good condition. Remove all three bolts completely and retain them if in good condition. Note the position of any ground straps or brackets attached to the mounting bolts.
6. 6

   Inspect and clean mounting area
   With the IPM removed, inspect the mounting surface and ground connection points. Use a wire brush to clean any corrosion from ground mounting points. Check all connectors for corrosion, damaged pins, or melted plastic. Clean connector faces with electrical contact cleaner if needed.
7. 7

   Transfer fuses and relays to new IPM
   Using your documentation, transfer all fuses and relays from the old IPM to the new unit in their exact original positions. Verify each fuse amperage rating matches the diagram on the fuse box cover. Ensure relays are fully seated in their sockets.
8. 8

   Position new IPM and install mounting bolts
   Position the new IPM in the mounting location, ensuring any ground straps are positioned under the appropriate mounting bolts. Install all three mounting bolts and tighten in a crossing pattern. Tighten securely but do not overtighten, as the mounting points may be plastic reinforced.
9. 9

   Reconnect wire harness connectors
   Reconnect all wire harness connectors to the IPM, ensuring each connector is fully seated and the locking tabs engage with an audible click. Verify each connector is secure by gently pulling on the connector body (not the wires). Match connector positions to your reference photos.
   ⚠Ensure connectors are aligned properly before pressing them together. Misaligned pins will bend and cause electrical faults.
10. 10

    Reinstall air intake components
    If removed, reinstall the air intake tube to the turbocharger inlet. Ensure the tube is fully seated and tighten the hose clamp securely. Verify no tools or debris have been left in the intake path.
11. 11

    Reconnect batteries and test
    Reconnect the negative terminal to both batteries, both of which are on the passenger side. Tighten terminals securely with a 13mm wrench. Turn the ignition to ON (do not start) and verify the IPM powers up and all dash warning lights illuminate normally. Tighten terminals securely with a 13mm wrench. Turn the ignition to ON (do not start) and verify the IPM powers up and all dash warning lights illuminate normally.
12. 12

    Install fuse box cover and perform system check
    Install the IPM cover, ensuring all tabs engage properly. Start the engine and verify normal operation. Test all major electrical systems including lights, wipers, power windows, HVAC blower, and horn to confirm proper fuse box operation.

Reassembly

1. Ensure all wire harness connectors are fully seated with locking tabs engaged
2. Verify all fuses and relays are installed in correct positions per fuse box diagram
3. Check that no tools or parts have been left in the engine bay
4. Ensure air intake system is properly sealed if it was removed for access

Verification

• Turn ignition to ON position and verify all dash warning lights illuminate normally then extinguish after starting
• Test all major electrical circuits: headlights (high and low beam), turn signals, brake lights, horn, wipers, power windows, and HVAC blower
• Start engine and verify normal charging system operation (battery gauge shows charging)
• Check for any warning lights or electrical fault codes using a scan tool if available
• Verify no blown fuses by visual inspection through fuse box cover window if equipped

Related trouble codes on this vehicle

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