Code
B1437
ALFA ROMEO
B — Body
High/low wiper speed relay coil short to ground
Views:
UK: 5
EN: 7
RU: 6
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring in the relay coil circuit causing insulation to contact chassis ground
- Failed wiper speed relay with internal coil short to ground
- Corroded or water-damaged relay connector or harness connector creating a short
- Faulty Body Control Module (BCM) / wiper module driver transistor shorted to ground
- Incorrect or aftermarket relay fitted with wrong pinout or internal fault
- Aftermarket equipment or recent repairs that disturbed the wiper harness
Symptoms
- Wipers inoperative or stuck on single speed
- Intermittent wiper function or loss of one speed (high or low)
- Blown fuse or repeated fuse failure in wiper circuit
- Instrument cluster or BCM stores B1437 and may show related body/wiper warnings
- Unusual relay heating or burning smell near relay area
What to check
- Read and record freeze frame and stored codes with a diagnostic scanner; clear and re-scan after tests
- Visually inspect relay, relay socket, harness, and ground points for corrosion, damage, water, or pin contamination
- Check relevant fuses for continuity and inspect for repeated failure
- With ignition OFF, disconnect relay and inspect relay pins and socket for corrosion or melted plastic
- Measure voltage at the relay supply terminal with ignition ON (should be battery voltage ≈ 11–14 V)
- Measure coil resistance across the relay coil terminals with relay removed (compare to specification)
Signal parameters
- Relay coil supply (battery) voltage: 11–14 V with ignition ON
- Expected relay coil resistance (typical): ~20–120 Ω (manufacturer-specific — check service data)
- Expected coil current when energized: roughly 80–300 mA (depends on relay)
- Control signal: usually BCM grounds or supplies one side of coil; expect to see switching (ground or +12 V) when wiper is commanded (use scope or DVOM)
Diagnostic algorithm
- Retrieve and record DTCs and any freeze frame data with a scan tool.
- Perform a visual inspection of relay, connector, harness routing, and ground points. Pay special attention to water ingress or chafing at bulkheads.
- With ignition OFF, remove the wiper speed relay. Inspect pins and socket; clean/repair corrosion or bent pins.
- Check fuses related to the wiper circuit and note if any have blown repeatedly.
- Measure battery voltage at the relay supply terminal with ignition ON (11–14 V expected). If missing, trace back to fuse/ignition feed.
- Measure coil resistance across the relay coil pins with the relay removed; compare to spec. If coil resistance is extremely low or open, replace relay.
- With relay removed, check continuity between the control coil terminal and chassis ground. If near zero ohms, there is a short to ground in wiring or at the BCM output.
- If no wiring short is found, back-probe the BCM/wiper module output while commanding wipers ON and observe whether the module is shorting the circuit to ground (use a current-limited bench supply or fused test lead to avoid damage).
- Swap in a known-good relay (correct OEM type) to verify whether the fault follows the relay. If substitution clears the fault, replace relay.
- If the relay and harness check OK but short persists only when BCM commands, suspect BCM/driver transistor failure — confirm with scope/current tracing and consult manufacturer repair procedures before replacing module.
- After repairs, clear codes and perform functional test over all wiper speeds. Re-scan to ensure B1437 remains absent.
- Document repairs and ensure any wiring damage is protected from future chafing or water exposure.
Likely causes
- Water ingress or corrosion at the wiper relay connector or harness splice
- Relay coil internally shorted or shorted to relay housing
- Abraded wiring where harness rubs on body or sharp edge near relay circuit
- BCM/wiper module output stage failure (internal short)
Fault status
Status
Wiper high/low speed relay coil circuit short to ground detected. Relay coil is seeing an unintended ground path when commanded; prevents correct wiper speed relay operation.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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