Horn System: Inspection

INSPECT HORN SWITCH
1. Disconnect the negative (-) terminal from the battery.
2. Remove the left and right covers from the steering wheel.
3. Using a Torx socket wrench, loosen the 2 bolts.
4. Pull up the horn pad and place it on the steering column, as shown.
  HINT:
  
  Do not disconnect the connector from the horn pad.
  
  Fig 1: Inspecting Horn Switch
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
5. Disconnect the connector from the slip ring.
6. Check that no continuity exists between terminal 6 of the connector and body ground.
7. Check that continuity exists between terminal 6 of the connector and body ground when the horn contact plate is pressed against the steering spoke assembly.
  If continuity is not as specified, repair or replace the steering wheel or wire harness as necessary.
8. Install the horn pad in place and using a Torx socket wrench, torque the 2 bolts.
  Torque: 7.1 N.m (72 kgf.cm, 62 in.lbf)
  
  Fig 2: Checking That Continuity
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
9. Install the left and right covers.
10. Connect the negative (-) terminal to the battery.
INSPECT HORN OPERATION
Connect the positive (+) lead from the battery to the terminal and negative (-) lead to the horn body and check that the horn blows.

If operation is not as specified, replace the horn.

Fig 3: Inspecting Horn Operation
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
INSPECT ENGINE ROOM R/B RELAY CIRCUIT (See INSPECTION )
HINT:

The horn relay is built in engine room junction block. Also the relay is constructed with a relay block that is in the junction block as a unit. To disconnect the wire harness connecting with relay block is impossible. If the relay has a malfunction, replace it with junction block assembly wire harness together.

Fig 4: Identifying Horn Relay Is Built In Engine Room Junction Block
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002