RAM 1500 Truck 4WD V8-5.9L VIN Z (2002)
Horn Relay: Description and Operation
HORN RELAY
The Horn Relay, which is internal to the Integrated Power Module (IPM), is controlled by the Front Control Module (FCM) through PCI bus
messages from the instrument cluster.
See: Body and Frame/Body Control Systems/Body Control Module
See: Powertrain Management/Computers and Control Systems/Information Bus
See: Instrument Panel, Gauges and Warning Indicators/Instrument Cluster / Carrier
These bus messages will be sent when either the horn switch is pressed which is hard wired to the instrument cluster, panic mode is requested from the
RKE or for vehicle theft security reasons (if equipped). Under normal operating conditions, if the horn is activated for more than 30 seconds, the FCM
will automatically deactivate the horn to prevent damage.
The FCM will reactivate control of the relay after a 25 second cool-down period. The relay control circuit is continuously monitored for malfunctions
that the FCM will report as DTC's.
