B2889

Code

Generic B — Body

Seat heater circuit malfunction

Brand: Generic

Type: B — Body

Views: UK: 7 EN: 8 RU: 5

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Page language: EN

Causes

Blown fuse or tripped circuit breaker for seat heater
Open or shorted wiring harness or connector
Failed seat heater element (broken filament or high resistance)
Faulty seat heater switch or control module
Poor ground connection at seat or module
Corrosion or water ingress in connector or seat

Symptoms

Seat heating does not operate or heats only intermittently
Partial or uneven heating across the seat surface
Heater works on some settings but not others
Warning light or message on dash for seat heater
Electrical odor or localized overheating (rare)

What to check

Scan vehicle for additional related trouble codes (seat heater, airbag/occupant detection if equipped)
Inspect fuses and circuit breakers for the seat heater circuit
Perform visual inspection of seat wiring, connectors and module for damage, corrosion, or water
Check connector pin tightness and presence of corrosion or bent pins
Measure supply voltage at seat heater connector with switch ON
Measure resistance/continuity of heater element per manufacturer's procedure

Signal parameters

Expected supply voltage at connector: ~12 V (battery) with ignition or seat-heater circuit ON
Heater element resistance (typical range): approximately 1–10 ohms (varies by vehicle and seat design) — consult vehicle spec
Control module output may be PWM; typical frequency range 1–200 Hz depending on manufacturer
Expected current draw: typically 1–10 A per seat circuit depending on heater stage and seat element
Continuity: near zero/low ohms across element when intact; infinite/open for a broken element

Diagnostic algorithm

Safety: Park, key off, and disconnect battery negative if you will be disconnecting connectors or performing repairs that could short.
Retrieve codes and freeze/frame data with scan tool. Note which seat (left/right) and any related codes.
Visually inspect fuse(s) and relays for seat heater circuit. Replace blown fuses with proper rating and retest.
Inspect harness routing under seat and at door sill for chafing, pinched wires or water damage. Wiggle test connectors while monitoring for change in behavior.
With ignition/seat-heater ON, measure battery voltage at power feed pin of seat heater connector. If no voltage, trace back to relay/fuse/ignition feed.
Measure resistance of the heater element per service manual. Remove connector and check element resistance across element terminals. If open or out of spec, replace seat heater pad/element.
Check ground: measure voltage drop between seat ground and battery negative while heater is ON. Excessive drop indicates poor ground needing repair.
If supply and ground OK but heater does not heat, check control module/switch output. Use scope to check for PWM control signal or multimeter to observe switching behavior.
If intermittent fault, perform wiggle/stress tests on wiring and connectors while monitoring with scan tool or multimeter to reproduce fault.
Repair or replace damaged wiring, connector, fuse, relay, element, switch or control module as indicated. Reassemble, clear codes and verify operation on all settings and after a short drive cycle.
After repair, perform final scan to confirm code does not return and verify no secondary faults (occupant detection/airbag systems often integrated with seat electronics).

Likely causes

Connector corrosion or damaged wiring at the seat
High resistance in heater element due to internal break or wear
Intermittent connector contact causing open circuit detection
Failed seat heater control module or switch
Blown fuse or incorrectly rated replacement fuse

Fault status

⚠️ Status

Seat heater circuit malfunction detected — possible open, short, high resistance, or control/connection fault. Inspect fuses, wiring, connectors, heater element and control module.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours