[Mgs] Intermittent horn

Paul Hunt paul.hunt1 at blueyonder.co.uk
Wed May 28 01:55:26 MDT 2008


Sounds like bad connections, so that when the voltage is lower when idling or
stopped there isn't enough power.

Your horns should have 2 terminals - one with purple wires (the fused 12v
supply) and the other with purple/black (the ground from the button).

Connect a voltmeter between ground and purple on the right-hand (facing
forwards) horn and you should see battery voltage.  Press the horn button and
the horns should sound and the voltage drop only slightly.  If it drops
several volts and the horns don't sound then there is a bad connection back
towards the fusebox, probably in the fusebox itself where the fuse to the
holder, the riveted connection between the holder and the spades on the back,
the wire connectors to the spades, and even inside the fuse itself can all
develop bad connections.

When you have a good 12v supply to the horns connect the meter between ground
and the purple/black.  This should also show 12v with the button released, but
should show zero volts with it pressed.  If this doesn't drop to zero there is
a bad connection back towards the horn button through the steering wheel
brush, steering wheel (several connections), the horn button, the steering
column inner, column outer, front cross-member to the body.

Even if it isn't a 'fixed' bad connection but an intermittent as has been
suggested it should be easy enough to track down if they don't work with the
engine switched off.

My V8 had a couple of these 'fixed' bad connections so much so that the PO had
fitted what looked like a scooter horn, which hardly sounded appropriate for a
V8.  Because the problems were inside the column (not uncommon on rubber
bumper cars it seems) and the after-market button I opted to add a relay,
which takes much less current than the horns and is unaffected by the bad
connections.

PaulH.

  ----- Original Message -----
  ... And typically it
  seems like it works when the car is driving, but rarely when it's idling and
  never when the car isn't running.


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