Code
B1217
ALFA ROMEO
B — Body
Horn relay coil circuit
Views:
UK: 6
EN: 10
RU: 7
AI status
Completed
Completed
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Causes
- Blown horn fuse
- Faulty horn relay (coil open or shorted)
- Open or short in wiring to relay coil (broken wire, damaged insulation)
- Poor or corroded connector/terminal at relay, fuse box, or ground
- Faulty horn switch (steering wheel/clockspring) or stuck contact
- Faulty Body Control Module (BCM) or related driver circuit
Symptoms
- Horn does not sound when horn button is pressed
- Horn works intermittently or only after manipulating connectors
- No audible click from horn relay when button pressed
- Horn stuck on (less common for coil open; more likely short/crossed circuit)
- Related instrument cluster or BCM warnings in some models
What to check
- Visually inspect horn fuse and associated fuses in fuse/relay box for blown element or heating discoloration
- Listen for relay click when horn button is pressed
- Inspect relay for signs of burning, melting or corrosion; swap with identical relay (if available) to test
- Check wiring and connectors at the relay/fuse box and at the horn(s) for corrosion, loose pins, or damaged insulation
- Verify steering wheel horn switch operation and inspect clock spring for damage if wiring to steering column is involved
- Scan BCM for stored faults and freeze frame data; clear codes and re-test to confirm persistence
Signal parameters
- Relay coil expected activation voltage: ~11–14 V (vehicle battery voltage) at the relay coil feed when horn is requested
- Control/ground path: relay coil ground or driver signal from BCM/steering switch should be pulled to chassis ground or switched to ground when activated
- Coil resistance (typical range): roughly 60–200 ohms (varies by relay); a very high or infinite resistance indicates open coil
- Activation behavior: steady voltage present while horn button held; no PWM unless specified by manufacturer
Diagnostic algorithm
- Retrieve and record stored codes from BCM and related modules; note freeze-frame or event data
- Visually inspect horn fuse and relay; replace fuse if blown and retest (do not continue if fuse blows again)
- With ignition on, probe the relay socket: identify coil feed (battery +) and coil control (BCM/ground). Use wiring diagram for exact pinout
- Have an assistant press the horn while measuring voltage at the relay coil feed and coil control pin: feed should be ~battery voltage; control should switch to ground (or receive drive signal) when pressed
- If coil feed is present but control does not switch, check horn switch and clock spring continuity to BCM; test continuity to the BCM pin with connectors disconnected (refer to wiring diagram)
- If control switches but relay does not click, remove relay and measure coil resistance; replace relay if out of spec or open
- If relay clicks but horn does not sound, confirm voltage at horn connector when relay energizes; if present but horn silent, test/replace horn
- If harness or connector damage is found, repair with crimp/solder and heat-shrink or replace connectors; protect against corrosion
- If wiring and components test good but control signal is absent or abnormal, inspect BCM grounds and power; if necessary, consult manufacturer repair information and consider BCM replacement or reprogramming only after confirming harness and external components are good
- Clear codes and re-test to confirm repair; monitor for intermittent faults and perform wiggle tests while monitoring live data
Likely causes
- Blown fuse or intermittent fuse contact
- Relay coil open or internal short
- Wiring/connector fault between BCM, fuse/relay box and horn relay
- Faulty horn switch or clock spring causing no ground/drive signal
- Corrosion or mechanical damage at relay/fuse terminals
Fault status
Status
Fault detected in horn relay coil circuit — open, short or missing drive signal. Horn may be inoperative or intermittent.
Repair difficulty: Medium
Diagnostic time: 0.5–1.5 hours
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