B1261 — Solar radiation sensor short to ground

Causes

• Damaged or chafed wiring causing a direct short to chassis ground
• Corroded, pushed-out or damaged sensor connector / pins
• Failed solar radiation (sunload) sensor with internal short to ground
• Improper repair or aftermarket accessory causing wiring contact with body/chassis
• Climate control module or wiring harness connector fault (less common)

Symptoms

• HVAC automatic mode not responding to sunlight or behaves incorrectly (overheating or overcooling)
• Dash message or fault indicator for sunload/solar sensor (in some vehicles)
• Climate control may remain in a fixed vent/temperature behavior despite changes in light
• Possible stored B1261 fault code in climate control module

What to check

• Read stored codes and freeze frame with a diagnostic scan tool; note conditions when fault set
• Perform a visual inspection of the solar sensor, its mounting, and wiring harness for damage, corrosion, or signs of water entry
• Inspect connector pins for corrosion, pushed-out pins, bent pins, or melted plastic
• With ignition ON (engine off), backprobe the sensor connector and measure reference and signal voltages with a digital multimeter
• Check continuity between the sensor signal pin and chassis ground to confirm a short to ground
• Wiggle the harness and connector while watching live data or voltage to reproduce intermittent faults

Signal parameters

• Typical reference supply: 5 V (from climate control/BCM) — verify vehicle-specific spec
• Expected sensor output: variable 0.5–4.5 V (low in shade/dark, higher in bright sun) — depends on vehicle calibration
• Short-to-ground symptom: signal ≈ 0.0–0.2 V with ignition ON
• Short-to-battery symptom: signal near vehicle battery voltage (rare for this sensor)
• Open-circuit symptom: no reference or signal (infinite resistance)

Similar codes

Causes

• Damaged or chafed wiring causing a direct short to chassis ground
• Corroded, pushed-out or damaged sensor connector / pins
• Failed solar radiation (sunload) sensor with internal short to ground
• Improper repair or aftermarket accessory causing wiring contact with body/chassis
• Climate control module or wiring harness connector fault (less common)

Symptoms

• HVAC automatic mode not responding to sunlight or behaves incorrectly (overheating or overcooling)
• Dash message or fault indicator for sunload/solar sensor (in some vehicles)
• Climate control may remain in a fixed vent/temperature behavior despite changes in light
• Possible stored B1261 fault code in climate control module

What to check

• Read stored codes and freeze frame with a diagnostic scan tool; note conditions when fault set
• Perform a visual inspection of the solar sensor, its mounting, and wiring harness for damage, corrosion, or signs of water entry
• Inspect connector pins for corrosion, pushed-out pins, bent pins, or melted plastic
• With ignition ON (engine off), backprobe the sensor connector and measure reference and signal voltages with a digital multimeter
• Check continuity between the sensor signal pin and chassis ground to confirm a short to ground
• Wiggle the harness and connector while watching live data or voltage to reproduce intermittent faults

Signal parameters

• Typical reference supply: 5 V (from climate control/BCM) — verify vehicle-specific spec
• Expected sensor output: variable 0.5–4.5 V (low in shade/dark, higher in bright sun) — depends on vehicle calibration
• Short-to-ground symptom: signal ≈ 0.0–0.2 V with ignition ON
• Short-to-battery symptom: signal near vehicle battery voltage (rare for this sensor)
• Open-circuit symptom: no reference or signal (infinite resistance)

Similar codes

Causes

• Damaged or chafed wiring causing a direct short to chassis ground
• Corroded, pushed-out or damaged sensor connector / pins
• Failed solar radiation (sunload) sensor with internal short to ground
• Improper repair or aftermarket accessory causing wiring contact with body/chassis
• Climate control module or wiring harness connector fault (less common)

Symptoms

• HVAC automatic mode not responding to sunlight or behaves incorrectly (overheating or overcooling)
• Dash message or fault indicator for sunload/solar sensor (in some vehicles)
• Climate control may remain in a fixed vent/temperature behavior despite changes in light
• Possible stored B1261 fault code in climate control module

What to check

• Read stored codes and freeze frame with a diagnostic scan tool; note conditions when fault set
• Perform a visual inspection of the solar sensor, its mounting, and wiring harness for damage, corrosion, or signs of water entry
• Inspect connector pins for corrosion, pushed-out pins, bent pins, or melted plastic
• With ignition ON (engine off), backprobe the sensor connector and measure reference and signal voltages with a digital multimeter
• Check continuity between the sensor signal pin and chassis ground to confirm a short to ground
• Wiggle the harness and connector while watching live data or voltage to reproduce intermittent faults

Signal parameters

• Typical reference supply: 5 V (from climate control/BCM) — verify vehicle-specific spec
• Expected sensor output: variable 0.5–4.5 V (low in shade/dark, higher in bright sun) — depends on vehicle calibration
• Short-to-ground symptom: signal ≈ 0.0–0.2 V with ignition ON
• Short-to-battery symptom: signal near vehicle battery voltage (rare for this sensor)
• Open-circuit symptom: no reference or signal (infinite resistance)

Similar codes

Causes

• Damaged or chafed wiring causing a direct short to chassis ground
• Corroded, pushed-out or damaged sensor connector / pins
• Failed solar radiation (sunload) sensor with internal short to ground
• Improper repair or aftermarket accessory causing wiring contact with body/chassis
• Climate control module or wiring harness connector fault (less common)

Symptoms

• HVAC automatic mode not responding to sunlight or behaves incorrectly (overheating or overcooling)
• Dash message or fault indicator for sunload/solar sensor (in some vehicles)
• Climate control may remain in a fixed vent/temperature behavior despite changes in light
• Possible stored B1261 fault code in climate control module

What to check

• Read stored codes and freeze frame with a diagnostic scan tool; note conditions when fault set
• Perform a visual inspection of the solar sensor, its mounting, and wiring harness for damage, corrosion, or signs of water entry
• Inspect connector pins for corrosion, pushed-out pins, bent pins, or melted plastic
• With ignition ON (engine off), backprobe the sensor connector and measure reference and signal voltages with a digital multimeter
• Check continuity between the sensor signal pin and chassis ground to confirm a short to ground
• Wiggle the harness and connector while watching live data or voltage to reproduce intermittent faults

Signal parameters

• Typical reference supply: 5 V (from climate control/BCM) — verify vehicle-specific spec
• Expected sensor output: variable 0.5–4.5 V (low in shade/dark, higher in bright sun) — depends on vehicle calibration
• Short-to-ground symptom: signal ≈ 0.0–0.2 V with ignition ON
• Short-to-battery symptom: signal near vehicle battery voltage (rare for this sensor)
• Open-circuit symptom: no reference or signal (infinite resistance)

Similar codes