B1122

Code

LAND ROVER B — Body

Window isolation relay

Brand: LAND ROVER

Type: B — Body

Views: UK: 31 EN: 55 RU: 40

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Page language: EN

Causes

Failed or sticking window isolation relay
Blown or poor fuse supplying the relay
Open, short or high-resistance wiring in relay supply, control or ground circuits
Corroded or loose relay socket or connector
Water ingress or corrosion in door harness or relay area
Faulty body control module (BCM) or module driver output

Symptoms

Power windows inoperative or work intermittently
One or more windows only operate with ignition on or not at all
Central locking or related body functions affected (depending on system)
Interior warning message or stored body electrical faults on scan tool
Possible parasitic battery drain if relay stuck closed

What to check

Read all stored codes and freeze frame data; check for related body/BCM codes
Visually inspect relay, relay socket, associated fuses and connectors for corrosion, water, or damage
Check fuse for continuity and correct rating
Measure supply voltage to relay with ignition on (battery voltage expected)
Check ground at relay socket for good continuity to chassis
Scan for BCM outputs when commanding windows or when fault sets

Signal parameters

Relay supply voltage: battery voltage (~11–15 V) with ignition/accessory or when system demands power
Relay control signal: switched by BCM — normally 0 V (ground) or battery positive when energized depending on design
Relay coil resistance (typical): generally tens to a few hundred ohms — refer to vehicle-specific data
Relay contact state: continuity between common and normally-open (NO) when energized, open when not energized
No excessive voltage drop at relay supply or ground (should be < ~0.5 V under load)

Diagnostic algorithm

Connect a diagnostic scanner and record B1122 and any other body/BCM codes; note conditions when code set.
Visually inspect relay, socket, connectors, fuses and nearby wiring for corrosion, water or damage; repair as needed.
Verify fuse supplying the relay has continuity and correct rating; replace if blown.
With ignition in required state, measure battery voltage at relay supply terminal and ground continuity at relay socket.
Command windows from the switch or use scanner to energize relay while measuring control signal from BCM at the relay coil pin; confirm correct switching voltage or ground.
Test relay operation by energizing coil (bench test or vehicle) and verify contact continuity between common and NO terminal. Replace relay if it fails.
If relay and fuses are good, backprobe/control wire and check for open/short between relay and BCM; repair any damaged wiring or connectors.
If wiring and relay are confirmed good but control signal is absent or incorrect, test BCM output and grounds. Check for related BCM codes and perform module tests or reflash per manufacturer guidance before replacing.
After repairs, clear codes, re-test window operation under several conditions, and monitor for return of the fault. Use data logging if intermittent.

Likely causes

Failed relay or internal contact welding/sticking
Corroded/loose connector at the relay or harness
Blown fuse in the window/auxiliary fuse circuit
Open/shorted control wire from BCM to relay
BCM driver fault (after verifying wiring and relay)

Fault status

⚠️ Status

Window isolation relay circuit fault — relay or its control/supply/ground circuit is reporting abnormal operation.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5 - 2.0 hours

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Repair manuals

Manual library for LAND ROVER

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Browse 413 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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B1122 — Window isolation relay