Hugh,
1. Check the "brush", located under the horn button. It should show
continuity when checked with an ohm meter (one probe to each end).
2. Using the ohm meter, check the "steering wheel" to ground connection.
It should read near zero. Check this from a point where the outer
diameter of the horn button contacts the steering column.
3. If the "steering wheel" does not read continuity to zero, check the
"jumper wire", located at the rubber coupling next to the brake booster.
It should be connected from the top shaft, coming from the steering
wheel, across the "joint", and to the lower shaft, that goes to the
steering rack. It should show continuity across the joint. Also check to
see if the lower end is connected to "ground", using the meter. If both
ends of the jumper wire (still in place), show continuity to ground, then
the problem is back toward the steering wheel. If not then the problem is
toward the steering rack end.
At the rack end:
There is a wire located under the "grease port" on the rack. That wire
should also show continuity to ground. It leads into the wiring harness
and finally to one of the ground points at the front of the engine bay.
At the steering wheel end:
If the "steering wheel" checks OK to ground, and the "brush" has
continuity through it, then the problem lies in the wiring from the horn
"relay" to the "slip ring". You
should show continuity from the "slip ring" to the terminal on the horn
relay - The same terminal that you grounded earlier in order to check the
function of the relay itself. If you do not show continuity, then this is
where the problem is - in the wire leading from the relay to the slip
ring.
HTH, and Good Luck
Mark Riddle
"72 TR6 Restoration underway
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