Horn Relay

This procedure covers the diagnosis, location, and replacement of the horn relay in a 2007 Ram 3500 with the 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Horn relay × 1 — Use OEM specification - Mopar 04692298 or equivalent

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn ignition to OFF position and remove key
3. Allow engine to cool if recently operated for safer access to engine compartment
4. Locate the Totally Integrated Power Module (TIPM) on the driver's side of the engine compartment near the battery

Procedure

1. 1

   Locate the TIPM
   Open the hood and identify the black Power Distribution Center (PDC) box mounted on the driver's side of the engine compartment near the battery. This rectangular box contains the relays and fuses for the vehicle.
2. 2

   Remove TIPM cover
   Use a flathead screwdriver or trim removal tool to gently release the retaining clips on the PDC cover. Lift the cover upward and away from the module. The relay and fuse diagram is typically printed on the underside of the cover.
3. 3

   Identify horn relay location
   Consult the diagram on the PDC cover to locate the horn relay position. The horn relay is typically located in the lower section of the relay block and is labeled on the diagram. It is a small cube-shaped relay, usually black or dark gray in color.
4. 4

   Test relay function (optional diagnostic step)
   If diagnosing a horn issue, you can test the relay before removal. With the PDC cover off and ignition ON, have an assistant press the horn button while you listen and feel for the relay clicking. A clicking relay that produces no horn sound suggests wiring or horn issues rather than relay failure. No click suggests relay or switch circuit failure.
5. 5

   Remove old horn relay
   Grasp the horn relay firmly between thumb and forefinger. Pull straight upward with steady, even pressure to remove the relay from its socket. The relay has blade-type terminals that friction-fit into the socket. If stuck, gently rock the relay side-to-side while pulling upward. Do not use excessive force or pry tools that could damage the socket.
6. 6

   Inspect relay socket
   Examine the relay socket terminals for corrosion, damage, or melting. The socket should have clean, spring-loaded contacts. If corrosion is present, clean gently with electrical contact cleaner. Damaged sockets may require PDC replacement by a qualified technician.
7. 7

   Install new horn relay
   Align the new horn relay with the socket, ensuring the relay terminals match the socket configuration. The relay will only fit in one orientation. Press the relay firmly into the socket until it is fully seated and flush with surrounding relays. You should feel it click into place.
8. 8

   Reinstall TIPM cover
   Position the PDC cover over the module, ensuring the diagram faces outward for future reference. Press down firmly on the cover until the retaining clips snap into place with an audible click. Verify the cover is secure and fully seated.

Reassembly

1. Ensure TIPM cover is securely fastened with both clips engaged
2. Verify no tools or parts are left in the engine compartment

Verification

• Turn ignition to ON position without starting the engine
• Press the horn button on the steering wheel and verify the horn sounds clearly and continuously while pressed
• Test both high and low horn tones if vehicle is equipped with dual-tone horns
• Verify no warning lights appear on the instrument cluster related to electrical system faults
• If horn still does not function, verify horn button operation, wiring continuity, and horn assembly condition

Related trouble codes on this vehicle

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