Code
B0189
HUMMER
B — Body
Solar Load Sensor #2 Circuit Range (sunload)
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring between solar sensor #2 and control module
- Corroded, loose, or contaminated connector at the sensor
- Failed solar load (sunload) sensor #2
- Incorrect reference voltage or ground at the sensor (power supply fault)
- Water intrusion or physical damage to the sensor or roof module
- Control module fault (rare) or incorrect software/calibration
Symptoms
- Automatic HVAC/automatic climate control may behave incorrectly (overcooling/heating or poor blending)
- Solar-based cabin temperature compensation not working
- DTC stored and possible MIL/indicator depending on system
- Erratic cabin temperature control or delayed climate response
What to check
- Retrieve freeze frame and live data for solar sensor #2 with a scan tool
- Visually inspect sensor location (roof/dash), connector, and wiring for damage or moisture
- Backprobe connector and check sensor supply (reference) voltage and ground
- Measure sensor signal voltage while changing ambient sunlight (cover/uncover sensor)
- Wiggle harness while monitoring for intermittent signal changes
- Check related fuses and BCM/HVAC module grounds
Signal parameters
- Sensor is a photodiode/photocell that produces a voltage proportional to irradiance
- Typical output range (generic): approx. 0.5–4.5 V depending on light level (some systems use 0–5 V)
- Diagnostic thresholds (generic): 4.8 V often flagged as out-of-range
- Reference supply typically a regulated 5 V reference and a ground return
Diagnostic algorithm
- Read and record freeze frame and live data for solar load sensor #2. Note when code set and ambient conditions.
- Clear the code and perform a functional test: monitor live sensor voltage while exposing and shielding the sensor to sunlight. Confirm voltage changes smoothly with light levels.
- Visually inspect sensor assembly and harness for corrosion, damaged insulation, or water ingress. Repair or dry/clean connectors as required.
- With ignition ON, backprobe connector: verify reference voltage (≈5 V) and ground continuity to module ground. Repair any missing supply or poor ground.
- Check signal wire for short to battery or short to ground using a multimeter (voltage/continuity). Repair wiring as needed.
- If wiring and supplies are good but signal remains out of range or unstable, swap with a known-good sensor (if available) or replace solar load sensor #2.
- After repair, erase codes and retest under varied light conditions to confirm proper operation and that code does not return.
- If problem persists with good sensor and wiring, consider diagnosing control module input circuitry or software updates per manufacturer service information.
Likely causes
- Damaged harness or pin corrosion at sensor connector
- Sensor exposed to moisture or physical impact
- Blown fuse or missing 5 V reference supply to sensor
- Intermittent connection due to vibration/wiring chafe
Fault status
Status
Solar Load Sensor #2 Circuit Range — sensor signal out of allowable range (sunload).
Repair difficulty: Medium
Diagnostic time: 0.5-1.5 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
Browse 138 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
HUMMER
-
HUMMER: 2009
-
HUMMER: 2008
-
HUMMER: 2007
-
HUMMER: 2005
-
HUMMER: 2004
-
HUMMER: 2000
-
HUMMER: 1999
-
HUMMER: 1994
-
HUMMER: 1993
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email