When the horn switch is pressed, a message is sent from the
instrument cluster via the network communication link to the
FEM. The
FEM receives the message and energizes the horn relay by grounding the horn relay
coil, allowing the dual note horn to sound.
The horn relay is relay #6 located in the Auxiliary Junction Box under the hood.
Possible causes of the horn always on are:
- auxiliary junction box fuse 4 (15A)
- the (GY/OG) wire at the
instrument cluster is shorted to ground
- the (RD/YE) wire at the Auxiliary Junction Box is shorted to power
- the (BN/RD) wire at the
FEM is shorted to ground
- shorted
clock spring
- horn relay
- horn
- horn switches
-
instrument cluster
- defective
FEM
Possible causes of the horn not operating are:
- auxiliary junction box fuse 4 (15A)
- the (GY/OG) wire in the
instrument cluster is open
- the (RD/BU) wire at the Auxiliary Junction Box is open or shorted to ground
- the (RD/YE) wire at the Auxiliary Junction Box is open or shorted to ground
- the (RD/YE) wire at the horn is open or shorted to ground
- the (BK) wire at the horn open
- the (BK/GN) at the
clock spring is open
- the (BN/RD) wire in the main harness is open
- open
clock spring
- horn relay
- horn
- horn switches
-
FEM
-
instrument cluster
doug7740
1955 Thunderbird Blue