[T3] Turn Signal Switch/Cancel Ring

[Jim Adney]

On 12 Apr 2012 at 16:58, Gary Forsmo wrote:

> In the Bentley book, Section 7, Page 33, Figure 10-15 ...
> Is that jumper wire (marked A & B to the coupling bolts) which
> spans(?), or  does it go up through, the expanded steel tube of the
> steering column ... the ground wire from the horn?

It's the ground wire from the horn ring. It comes down the inside of 
the hollow steering shaft and jumps across the Insulating flexible 
coupler. Then there is a short jumper from the steering gearbox to 
the body, which is necessary to ground the gearbox because of the 
rubber front axle mounting bushings.

> Is the horn insulated from the bumper where it bolts on?   Otherwise,
> wouldn't the front bumper also be "hot" with 12 volts?

The body of the horn is not hot. It's internal circuitry is hot. It 
has 2 terminals: One gets power directly from the fuse box while the 
other goes up and connects to the outer race of one of the steering 
shaft bearings. Those bearings sit in plastic cups that insulate them 
from the body but not from the steering shaft. So grounding the 
steering shaft completes the horn circuit.

> So when I had an "intermittent horn" (when my front bumper was mounted
> on the car and the horn mounted on the bumper) THAT ground wire may
> have been the source of my "sometimes OK" and "sometimes NOT OK' horn
> operation?

The occasional "excess" horn blast is usually caused by either an 
incorrectly installed horn ring, that grounds when it shouldn't, or 
by the insulation on the wire down the center of the steering shaft 
wearing thru, usually at the bottom end, and grounding the steering 
shaft.

> Could "rusty" bumper mounts where the bumper mounts to the uni-body,
> been the source of the intermittent horn operation?

No.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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