The next test will determine if the problem is with the airbag sliding contact or horn switch. The airbag sliding contact connector is labeled C234. The drawing shows it is either on top of the steering column or on the right side. You'll need a jumper wire or test light and the horn relay in place.
Using the jumper or test light, ground the dark blue wire. This will complete the switch side of the circuit for the horn. If the horn sounds then you have power up to the connector for the sliding contact and can proceed with the following.
Next move the jumper to the connector C292, at the base of the steering column, and ground the same dark blue wire. This will test after the sliding contact but before the horn switch
Still at the connector for the steering column, move the jumper and ground the dark green/orange wire and push the horn button. This will test the first sliding contact and horn switch.
Moving back to the connector for the sliding contacts, ground the dark green/orange wire and again push the horn button. This will test the first sliding contact, horn switch and 2nd sliding contact.
Need to know if the horn sounds in all tests, or where it doesn't.