Horn fuse

Discussion in 'KJ General Discussion' started by TikiX, May 21, 2020 at 2:52 PM.

  1. TikiX

    TikiX New Member

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    Im looking over a friend’s 02 Liberty she recently bought, she mentioned the horn does not work.
    I checked the fuse, and there is no fuse in that slot, so I pulled another 15 amp to put into the horn fuse position, and the horn comes on as soon as the prongs touch.
    Does that mean there’s a short in the horn wiring?
    Pretty obvious the previous owner solved the problem by just pulling the fuse. Maybe because it would be a tough task to trace down the fault?
    Any easy first steps you can recommend?

    Possibly related, the airbag warning light stays on. Maybe there’s some general wiring issue in the steering column?
     
    Last edited: May 21, 2020 at 3:37 PM
  2. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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  3. TikiX

    TikiX New Member

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  4. Billwill

    Billwill Full Access Member

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    The fact that the Airbag warning light comes on together with a horn problem leads me to believe that the Clock Spring may be faulty.o_O

    This is a flat nylon belt that has copper tracks on it that provide data from the steering wheel boss to the electrics such as Horn On, Steering Boss Airbag Activation, cruise control, radio operation etc.

    The 2006/7 KJ with ESP also has a track to determine the exact angle of the steering wheel.

    These Clock Springs get brittle with age and cause hairline cracks in the copper tracks....may be a permanent crack or may only open up when the steering wheel moves to a certain position.;)

    I had two Airbag problems on my 2002 Export CRD.

    On my RHD KJ the Clock Spring connecting cable goes down the column and connects to a small five-wire connector just behind the panel that you tend to bump your knees on. This small connector had a bad pin on it...I would fix the male/female pin and the Air Bag light would stay OFF for a while then come back again.
    I got tired of this so cut the male and female plugs off and connected the wires straight through. An interesting thing about this small connector is that inside the plug is a small spring-loaded flat metal plate that shorts out the pins going up to the steering boss....this is to stop Back-EMF from running up the cable and energizing the Air Bag!
    I was informed by an owner of a RHD KJ that this short section of cable does not exist on the RHD KJs!:confused:

    After fixing this problem...years later I started getting the Air Bag light coming ON again....this only happened when turning the Steering Wheel in one direction and steadily got worse so it was obviously the Clock Spring failing!

    If you work on the steering boss area ie. intend removing the plastic cover with the horn and other controls on it....or if you intend replacing the Clock Spring... you must first disconnect the battery leads and tape the Red and Black leads together for 30 minutes to discharge any capacitance within the system which may set off the Air Bags!

    Then remove the plastic cover on the Boss...4 bolts 10mm if I remember correctly. Disconnect all plugs there..Horn, Air Bag etc.

    I believe that to replace the Clock Spring you need to remove the steering wheel...I am too lazy to look it up!;) I had to remove the whole steering column one time to replace the small bearing at the top of the column...Dealers did not have it....so I may be a bit confused...look it up in the 2002 Jeep KJ Service Manual Link given!

    Remove the bolt holding the steering wheel in place....13mm I think. Mark the exact position of the steering wheel to the splined shaft with a sharp tool so that you can get the steering wheel lined up properly again.

    Using a small two lever bearing puller...place a large nut over the exposed female thread and use the puller to lift the steering wheel off...the large nut protects the female thread from damage.

    Tape the Clock spring in place so that it does not unwind if you intend using it again so that you get it back into its original position....the Clock Spring is pre-wound about 2 turns so that you can turn the wheel both ways without snapping the Clock Spring.
    There is a clear plastic window on the Clock Spring assembly through which you should see a Flag that tells you the Clock Spring is in the correct position...the Jeep KJ tells you the procedure!

    The new Clock Spring assemblies from the Dealers comes with all the possibly needed copper tracks ie. for Cruise Control, Radio Controls etc. and ESP even if you do not need them!

    The new assembly from the dealer comes with a white plastic shipping plug holding the spring in its correct position...after you have fitted it in place and the Steering Wheel is bolted back in place you pull out this White Shipping plug!

    When all connectors have been re-plugged and the Steering Boss is Back in place re-connect the battery...make sure no person is sitting in the Driver's Seat!:oops:

    If I recall correctly the air bag light stays ON for a few days until the Jeep is happy that all is well.:)
     
    Last edited: May 22, 2020 at 6:36 AM
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  5. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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    With the airbag light on, It would be initially recommended that the jeep get scanned for the air bag codes.
    Hopefully the code/s may explain the fault location.
     
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  6. TikiX

    TikiX New Member

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    Billwill, that’s excellent info! But way off over my abilities, so it it comes to that I will defer to a shop.
    LibertyTC, good idea, I should check the codes before anything, see what’s there.
     
  7. Billwill

    Billwill Full Access Member

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    Yeah the horn blowing a fuse is unlikely to be the Clock Spring...I have seen breaks in the tracks of the Clock Spring for sure but unlikely that the tracks could short together. May be a short in the wiring somewhere under the Steering Boss though.

    Good idea to check for Air Bag codes as it could be somewhere else... there some Tech Bulletens issued for Air Bag issues....I would not be happy driving a vehicle with suspect airbags!:eek:

    Definitely take precautions as regards disconnecting the battery...I saw a post years ago where a worker at a BMW assembly plant saw a female co-worker killed when the airbag went off while she was working inside the vehicle!:(
     
    Last edited: May 23, 2020 at 5:19 AM
  8. Billwill

    Billwill Full Access Member

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    The Horn Wiring is on Page 8W-41-2. of the 2002 Jeep KJ Service Manual.

    Have you swapped the Horn Relay over with an identical one nearby...the contacts on the Relay may have welded together.

    This relay is mounted on the Junction Block which is on the rear side of the fuse panel....front side only has the High Beam Relay and if a Canadian model a large Daylight Running Relay as well. The rear side has several relays...only way to identify them is to look up the Junction Block in the Component Index at the front of Section 8W.

    The horn switch provides ground to the relay on pin 85...you need to check that the Black/Green wire coming off pin 85 is not constantly shorting to ground.

    The Body Control Module (BCM) also can supply ground to pin 85...when the doors are locked remotely or when someone tries to break in!

    The BCM is mounted on the Junction Block.

    If you own a KJ you definitely need to buy a cheap Digital Multimeter....you will need it a few times. My Fluke Meter sleeps in the Cargo Area constantly and my Laptop with all the KJ Manuals goes with me whenever I step into the Jeep....just in case I have a breakdown out on the open road!:eek: