B1771

Code

Other B — Body

Seat Driver Backward Circuit Short To Battery

Brand: Other

Type: B — Body

Views: UK: 27 EN: 38 RU: 34

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Page language: EN

Causes

Wiring shorted to battery positive (chafed wire contacting frame or other hot conductor)
Faulty/backward position switch or seat position sensor internally shorted
Corroded or damaged connector pin providing constant battery feed
Failed seat control module output stage
Aftermarket equipment or repair wiring incorrectly routed/connected
Water intrusion into seat base or connector

Symptoms

Driver seat will not move backward, or moves only in one direction
Seat moves erratically or stops mid-travel
DTC B1771 stored (may not illuminate MIL but stored in body/seat module)
Blown fuse or repeated fuse failure in seat circuit
Possible parasitic draw or battery-related symptoms if short is continuous

What to check

Retrieve freeze frame and related seat codes; note whether code is current or history
Visually inspect seat wiring, harness boots, and connectors for damage, corrosion, or moisture
Check seat track area for pinched or chafed wires where harness flexes
Inspect connector pins at the seat switch and seat control module for pushed pins or contamination
Check fuses and relays for the seat circuit
Perform a wiggle test of wiring while operating seat controls to reproduce fault

Signal parameters

Normal inactive voltage on backward circuit: near 0 V (or low logic voltage) with switch/module off
Activation voltage: near battery voltage (~11–14 V) when switch commanded ON
If short to battery exists: constant ~11–14 V present on backward circuit even with switch/module OFF
Resistance to battery positive should be high when circuit is open; low resistance indicates short
Typical current draw: increased if motor is stuck or shorted; significant current suggests a direct short or motor fault

Diagnostic algorithm

Read and record all stored codes and freeze-frame data using a scanner. Note whether B1771 is current or pending.
Clear the code, cycle ignition and seat operation to see if B1771 returns and whether it is intermittent or permanent.
VISUAL INSPECTION: With ignition OFF, inspect harness, connectors, seat tracks, and switch for damage or corrosion. Pay attention to areas that flex.
FUSE CHECK: Verify seat circuit fuses/relays are intact. Replace if blown, then verify whether fuse blows again when operating seat.
BACKPROBE VOLTAGE: With ignition ON, backprobe the backward control circuit at the switch and at the seat control module connector. With the switch not pressed the circuit should not show battery voltage. If it shows battery voltage constantly, suspect a short to B+ upstream.
CONTINUITY/SHORT TEST: With battery disconnected, measure continuity between the backward circuit and battery positive. A low resistance indicates a short. Also check resistance from the circuit to ground; unexpected low resistance to B+ indicates short.
ISOLATION: Disconnect the seat switch and/or seat control module harness and re-check the circuit. If the short disappears when a connector is disconnected, the short is in the downstream harness, switch, motor, or module.
SWITCH & MOTOR TEST: Test the backward switch for internal shorting using an ohmmeter. Bench-test the motor and switch if accessible. Replace faulty components as needed.
CHECK FOR WATER DAMAGE/AFTERMARKET: Inspect for water or non-factory wiring that may be tied into the circuit incorrectly; repair or remove as required.
REPAIR: Repair damaged wiring, replace connectors, replace switch or seat control module per findings. Use proper soldering or factory-style crimping and protect harness with loom and grommets where needed.
VERIFY: Reconnect everything, clear codes, and retest seat operation. Confirm B1771 does not return and that seat backward function works normally.

Likely causes

Pinched/chafed wire in seat track contacting a hot lead or metal
Damaged or pushed-in connector pin at the seat control switch or module
Internal failure of the seat switch (stuck closed to battery)
Corrosion or water-damaged harness in the seat area
High-resistance/shorted motor wiring backfeeding battery voltage

Fault status

⚠️ Status

Stored when the driver seat 'backward' circuit is detected shorted to battery positive. The body/seat control module logs the condition and may inhibit backward movement or set related body module faults until the short is cleared.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours