B1290

Code

Other B — Body

Servo Motor Potentiometer Airintake Right Circuit Short To Battery

Brand: Other

Type: B — Body

Views: UK: 23 EN: 35 RU: 30

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Page language: EN

Causes

Shorted wiring harness (signal wire contacting battery positive)
Corroded or damaged connector pins allowing battery voltage onto the signal
Failed/shorted potentiometer inside the right air intake servo (actuator)
Water intrusion or contamination at the actuator connector
Poor or missing ground causing abnormal voltages
Control module internal driver failure (less common)

Symptoms

Right intake/air door stuck in one position (recirculate or fresh air mismatch)
HVAC mode/airflow does not change correctly on one side
One-sided temperature control problems (if door affects airflow path)
Stored DTC for right intake potentiometer short to battery
Possible HVAC warning or reduced HVAC functionality

What to check

Retrieve and record freeze-frame data and related HVAC codes with a scan tool; clear codes and see if B1290 returns
Visual inspection of right air intake actuator, wiring harness, and connector for damage, corrosion, or water
Backprobe actuator connector and measure voltages while operating HVAC: check reference, signal, and supply voltages
With ignition ON, check for battery voltage present on the signal/feedback pin (should not be at 12V if healthy)
Measure resistance between the signal wire and battery positive with ignition off to check for a short
Disconnect the actuator and see if the short to battery condition clears (if it clears, likely actuator issue)

Signal parameters

Potentiometer reference voltage: typically ~5 V (varies by manufacturer)
Potentiometer signal output: normally varies between ~0.5–4.5 V as actuator moves
Short to battery condition: signal or feedback pin near battery voltage (~12 V)
Continuity: signal wire should not have low resistance to battery positive with ignition OFF

Diagnostic algorithm

Use a scan tool to confirm B1290 and note any related HVAC or body codes and freeze-frame data.
Turn ignition OFF. Perform a careful visual inspection of the right air intake servo, connector, and nearby harness for damaged insulation, pin corrosion, or evidence of water.
Disconnect the right intake actuator connector. With ignition ON (accessory), measure voltage at the harness signal pin to chassis ground. If it is ~12 V with actuator disconnected, trace wiring toward fuse/12V source for a short.
With connector connected, operate the HVAC through modes while backprobing the signal, reference, and supply pins. A healthy potentiometer will show a varying signal around the reference voltage range; a short will show ~12 V or stuck reading.
Measure resistance between the signal wire and battery positive with ignition OFF. Low resistance indicates a direct short. If present, isolate sections by disconnecting connectors and retesting to locate the short.
If the short is present only with the actuator connected, suspect internal actuator potentiometer failure — replace the right air intake servo and retest.
If the short remains with actuator disconnected, repair wiring harness: locate chafes, pin contact points, or damaged insulation; repair or replace harness and connectors as needed.
After repairs or actuator replacement, clear codes and verify proper operation under all HVAC modes. Re-scan to confirm B1290 does not return.
If wiring and actuator are good but code persists, evaluate the HVAC control module for internal faults or incorrect 12V supply/ground routing and consult manufacturer documentation.

Likely causes

Damaged/chafed harness where it rubs on body panels near the HVAC unit
Failed actuator potentiometer with internal short to the 12V supply
Connector pin pushed out or bent making contact with 12V terminal
Water or debris in connector near the right intake actuator

Fault status

⚠️ Status

Control module detected the right air intake servo motor potentiometer feedback circuit driven to battery voltage (short to battery). Position feedback invalid — HVAC cannot determine intake door position.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours