B28C7

Code

Generic B — Body

Body Control Module: Interior Temperature Sensor Short to Ground

Brand: Generic

Type: B — Body

Views: UK: 13 EN: 20 RU: 13

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Short to ground in the interior temperature sensor wiring (chafed wire, pin contact with chassis).
Failed interior/cabin temperature sensor (NTC thermistor) with internal short.
Corroded or damaged sensor connector or terminal making unintended contact with ground.
Water intrusion in sensor or harness (condensation, leak).
Poor BCM ground, BCM internal fault, or BCM software calibration issue (less common).

Symptoms

Incorrect or fixed interior temperature reading shown by climate control system.
Automatic HVAC not maintaining commanded cabin temperature.
Climate control using full heating or cooling, or cycling abnormally.
Stored DTC B28C7 and possible related climate/HVAC fault messages.
Intermittent operation of automatic vent modes or blower behavior.

What to check

Read freeze-frame and live data from the BCM/HVAC module with a scan tool; note interior temperature sensor values.
Visually inspect sensor location, wiring harness and connector for damage, corrosion, dirt or water.
Backprobe sensor connector with ignition ON and measure signal voltage to ground and continuity to ground.
Measure sensor resistance at the connector and compare to expected thermistor behavior when ambient temperature changes.
Check continuity between sensor signal wire and chassis ground (should not be direct short).
Unplug the sensor and observe scanner data/BCM response (look for open-circuit diagnostic or change in symptom).

Signal parameters

Sensor type: typically an NTC thermistor (resistance falls as temperature rises).
Typical idle signal: resistance often in the kilohm range at ambient (example: ~10 kΩ at 25°C) — verify factory spec for exact values.
Typical BCM input: analog voltage within 0.5–4.5 V depending on sensor and ambient temperature — check service data for exact range.
Short-to-ground symptom: signal voltage near 0 V and/or continuity between signal pin and ground with very low resistance.
Open-circuit symptom: very high resistance or no continuity; scanner may show implausible temperature or ‘open’ status.

Diagnostic algorithm

Retrieve all stored codes and freeze-frame data. Note whether code is current or historic and if multiple HVAC/body codes are present.
Inspect the sensor and harness: locate the interior temperature sensor (commonly in dash, center console, or HVAC housing). Look for pin corrosion, damaged insulation, or water ingress.
With connector disconnected, measure resistance of the sensor across its terminals at known ambient temperature and compare to manufacturer spec or expected NTC behavior. If resistance is extremely low (near 0 Ω), suspect a shorted sensor; if open/infinite, suspect open sensor.
With ignition ON (engine off) backprobe the BCM/sensor signal wire and measure voltage to ground. A near-0 V reading indicates a short to ground. If voltage is within expected range, the sensor/harness may be OK.
Check continuity between the signal wire and chassis ground with the harness disconnected from the BCM. A direct short (very low ohms) confirms wiring short to ground.
Perform a wiggle/strain test on the wiring while monitoring live sensor data to find intermittent shorts. Inspect routing where harness passes through bulkheads or near sharp edges.
If wiring and connector are good, perform a bench test of the sensor (apply known resistance/voltage) and observe BCM response. If BCM input remains abnormal with a verified-good input, suspect BCM internal fault.
Repair any damaged wiring, replace corroded connectors or the sensor as required. Clear codes and retest system operation and live data to confirm fault does not recur.
If code returns after repair and wiring/sensor verified good, consult factory service documentation for BCM tests, reprogramming or replacement procedures.

Likely causes

Damaged/chafed sensor harness contacting chassis ground.
Corroded/contaminated connector at the sensor causing a low-resistance path to ground.
Failed interior temperature sensor internally shorted.
Faulty BCM input circuit (if wiring and sensor check good).

Fault status

⚠️ Status

BCM detected interior temperature sensor signal shorted to ground. Temperature input is invalid. HVAC/automatic climate functions may be affected. Code stored in BCM.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours