B1647

Code

Other B — Body

Seat Driver Recline Forward Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 23 EN: 39 RU: 31

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Page language: EN

Driver seat will not recline forward when commanded
No motor noise when attempting forward recline or strange clicking/noise
DTC B1647 stored in the body/seat control module
Intermittent operation — may work after moving seat or manipulating wiring/connector
Other seat memory or position functions may be affected if the seat module is involved

Visual inspection of wiring harness and connectors under the seat and at hinge points for damage, pinching, corrosion or disconnection
Check fuses and relays related to seat motors and seat module
With scanner, attempt to command recline forward and observe behavior and live data
Backprobing the motor connector to measure voltage on forward/reverse pins while commanding recline forward
Wiggle test harness while commanding to reproduce fault or intermittent
Inspect for mechanical binding in seat tracks and recliner mechanism

Nominal system supply: ~12 V battery (vehicle-specific) at motor power/relay feed
Recline forward command: battery voltage (~11–14 V) present on forward motor lead when commanded
Reverse command: forward lead should be near 0 V and reverse lead at battery voltage when reversing (opposite polarity control on many vehicles)
Motor coil resistance (typical range): low single-digit to tens of ohms — nominally
No-load current: typically a few amps; stall or mechanical bind can cause much higher current (several amps to >10 A) — consult vehicle spec
Open-circuit: infinite resistance; short-to-ground: near 0 V on a feed line

Retrieve freeze frame and full DTC list with a scan tool, note related codes
Safety: if removing seat or working near seat wiring with airbags, follow manufacturer procedure (disconnect battery and wait specified time)
Attempt to command recline forward with scanner and observe if DTC is active and whether motor responds
Listen for motor or relay activity. If no sound, backprobe motor connector and measure voltage on forward/reverse pins while commanding forward
If no command voltage at motor connector but module shows command, test continuity between module and motor connector for open/short (unplug connectors first)
Inspect wiring at common stress points (under seat, seat rail, hinge) for broken conductors; repair any chafed or broken wires
If voltage is present at motor connector when commanded but motor does not run, disconnect motor and bench-test motor directly with 12 V to verify motor function (brief pulses)
If motor draws excessive current or stalls, replace motor or free mechanical obstruction; if motor OK, check ground and related fuses/relays
If wiring and motor check OK, test/replace seat control module or recline switch per vehicle procedures
After repairs, clear codes and perform functional test by commanding multiple seat movements and verify no return of B1647