B2561

Code

Other B — Body

Aux A/C Blower Speed 1 Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 17 EN: 37 RU: 25

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Page language: EN

Causes

Blown fuse or faulty relay for auxiliary blower circuit
Open, shorted, damaged or corroded wiring or connector in the blower speed 1 circuit
Failed blower motor resistor pack or speed-control module
Faulty auxiliary blower motor (internal short or open)
Faulty HVAC control module or body control module output
Poor ground at blower motor or control module

Symptoms

Auxiliary A/C blower does not run on speed 1 (low)
Blower works on other speeds but not low, or blower does not run at all
HVAC blower noise or intermittent operation when switching speeds
DTC stored and HVAC-related warning message or reduced functionality

What to check

Read DTC and freeze-frame data with a scan tool; note vehicle operating conditions when code set
Visually inspect blower motor, resistor/control module, harness, connectors, and ground points for corrosion, damage or pin push-out
Check relevant fuses and relays feeding the auxiliary blower circuit
With HVAC set to blower speed 1, probe for expected supply voltage and ground at the blower motor connector
Measure resistance/continuity of blower motor and resistor pack (compare to specification)
Wiggle harness and connectors while operating blower to look for intermittent faults

Signal parameters

Expected supply voltage at blower motor fuse/relay: battery voltage (~12 V) when blower relay engaged
Voltage at blower motor connector when commanded to speed 1: reduced DC voltage or PWM signal depending on system — commonly a low duty cycle (e.g., ~10–30%) for low speed
Blower motor resistance (typical): low ohms (often 1–5 Ω) — consult vehicle spec
Resistor pack terminals: continuity across speed taps; open or very high resistance indicates failed resistor

Diagnostic algorithm

Connect a scan tool and confirm B2561; record freeze-frame, freeze-frame conditions, and any related HVAC codes.
Inspect fuses/relays for the auxiliary blower circuit; replace any blown fuses and swap relay with a known-good unit to test.
Visually inspect wiring, connectors, and grounds at the blower motor assembly and resistor/control module. Repair any corrosion, damaged insulation or loose pins.
With the connector connected, command blower to speed 1. Measure at the blower motor connector: supply voltage and ground presence. Note whether voltage is a low steady DC or a PWM signal and its approximate duty cycle.
If no supply or control signal present, back-probe upstream (relay/fuse/HVAC control output) to find open/short. Repair wiring as required.
If control signal present but blower does not run on speed 1, disconnect blower and measure resistance of motor and resistor pack speed taps. Replace failed resistor pack or blower motor if out of specification.
If resistor and motor test good, test/replace the HVAC control module or blower speed control module according to manufacturer procedures.
After repairs, clear codes and verify proper operation across all blower speeds; road/test as necessary to confirm intermittent faults are resolved.

Likely causes

Corroded/loose connector at blower motor or resistor pack
Failed blower motor resistor/speed control for low-speed tap
Open/shorted wire between HVAC module and blower assembly
Blown inline fuse or failed relay supplying the blower
Weak or intermittent ground causing loss of speed 1 signal

Fault status

⚠️ Status

Auxiliary A/C blower speed 1 circuit failure detected — control signal absent or out of range, open or short in circuit, or blower/resistor/module fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours