B1245

Code

ALFA ROMEO B — Body

Rear wiper relay circuit short to positive

Brand: ALFA ROMEO

Type: B — Body

Views: UK: 5 EN: 6 RU: 8

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Page language: EN

Shorted wiring in rear wiper relay/control circuit to battery positive
Faulty or welded relay whose contact/coil is feeding +12V into the control circuit
Corroded, damaged or water‑ingressed rear wiper relay connector or harness
Incorrectly fitted aftermarket accessory or jump‑lead creating a feed to the circuit
Body control module (BCM) or wiper module internal fault (less common)
Blown or poor ground causing circuit behavior to appear as a short to positive

Visually inspect the rear wiper relay, socket and associated connectors for corrosion, melted insulation or water ingress
Check rear wiper fuse(s) for condition and correct rating
With ignition OFF, disconnect the rear wiper relay and check if the fault clears or if circuit voltage to the control pin remains at battery +12V
Perform a visual harness inspection along the path from relay to motor and BCM for chafe, pinched wiring or aftermarket splices
Measure voltage at the relay control pin with a DMM: compare ignition OFF and ON, and when wiper is commanded
Check for a good ground at the wiper motor and relay ground point

Control circuit (relay coil) inactive: ~0 V (or open circuit) with ignition off
Control circuit active: ~12 V when relay is commanded ON (switch/module supplying +12 V or ground depending on design)
Relay coil resistance (typical): ~50–200 ohms (varies by relay); compare to specification if available
Motor power supply: ~12 V when wiper is commanded to run; near 0 V when not commanded (unless relay/wiring fault present)

Read and record freeze frame and number of occurrences; clear the DTC and see if it returns
Attempt to reproduce the complaint (operate rear wiper through all modes) while observing behavior and lamp/fuse status
Visually inspect relay, relay socket and wiring for damage, corrosion or water ingress
Remove rear wiper relay and re-check voltage on the control circuit with ignition OFF — if still at +12 V, there is a short to positive downstream of relay or at the control wiring
With relay removed, disconnect the rear wiper motor connector; check whether the short condition clears. If it clears, trace motor wiring and motor for internal short
Backprobing: measure voltage between the control wire and chassis ground with ignition OFF and ON and while commanding the wiper. A constant ~12 V with no command indicates a short to battery
Perform a resistance-to-battery test with ignition OFF: check for near‑zero ohms between the suspect control wire and B+ to confirm short (ensure power removed before resistance checks)
Bench‑test or swap relay with a known good relay of same type to determine if relay is at fault
If wiring and relay check good, test the BCM/wiper control module output for proper operation or intermittent faults; consult manufacturer wiring diagrams and component testing procedures
After repairs, clear codes and perform a full function test; re-scan to ensure the DTC does not return

Shorted/abraded wire contacting a chassis harness or bodywork and touching battery +12V at or near the rear wiper relay
Failed relay with stuck/welded contact feeding +12V back into the control wire
Water intrusion or corroded connector causing unintended continuity to positive

⚠️ Status

Stored fault: Rear wiper relay control circuit shorted to positive (B1245). Requires inspection of relay, harness and control module.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5–1.5 hours

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