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: Locating Horn Switch Connector
  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 For Continuity Between Terminal 6 Of Connector And Body Ground
  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.

Fig 3: Inspecting Horn Operation
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

If operation is not as specified, replace the horn.
INSPECT HORN SWITCH CIRCUIT
(See HORN CIRCUIT ) .

INSPECT HORN RELAY CONTINUITY

CHECKING HORN RELAY CONTINUITY

Condition	Tester connection	Specified condition
Constant	1 - 2	Continuity
Apply B+ between terminals 1 and 2.	3 - 5	Continuity

If continuity is not as specified, replace the relay.

Fig 4: Identifying Horn Relay Terminals & Internal Circuitry

INSPECT HORN RELAY CIRCUITS
(See HORN wiring diagram in SYSTEM WIRING DIAGRAMS article. )