Code
B1918
HUMMER
B — Body
Heated Seat Switch - Temperature Input Shorted to Battery
Views:
UK: 13
EN: 19
RU: 12
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring allowing the temperature input to contact a battery feed
- Corroded or melted connector pins creating a short to a 12V source
- Incorrectly routed or pinched harness contacting constant/switched 12V circuit
- Failed heated seat switch or control module with internal short
- Aftermarket equipment or previous repair miswiring the seat harness
Symptoms
- Heated seat(s) inoperative or stuck on high
- Seat heater indicator behaves erratically or shows abnormal temperature readings
- Blown seat heater fuse or repeated fuse failures
- Scan tool shows temperature input at near-battery voltage or unreasonable temperature values
- Possible parasitic drain when vehicle off if short is to constant battery feed
What to check
- Read and record freeze frame and active DTCs with a capable scan tool
- Visually inspect seat wiring harnesses, connectors, and seat tracks for damage, pinching, melted insulation or foreign metal
- Check fuses related to seat heaters for continuity and evidence of repeated failures
- Backprobe the seat temperature input pin at the switch/module and measure voltage with ignition ON (do not crank)
- Measure continuity between the temperature input wire and battery positive to confirm a short
- Inspect for aftermarket accessories or recent seat repairs that could have introduced miswiring
Signal parameters
- Normal temperature input: low-voltage signal to control module (typically 0–5 V sensor signal)
- Short to battery: input measures near battery voltage (≈12–14 V with ignition ON)
- Open/OL sensor: very high resistance or infinite between sensor terminals
- Thermistor behavior: resistance should change with temperature (expected direction: NTC decreases with increasing temperature)
Diagnostic algorithm
- Retrieve and record B1918 and any related codes with a scan tool; note freeze frame data and affected seat(s).
- Visually inspect the seat, harness, connectors and seat tracks for obvious damage, melted insulation, pinched wires, or signs of repair. Remove trim as needed to access connectors.
- Verify fuses for the heated seats; replace blown fuses only after finding and fixing the shorting condition.
- With ignition ON (engine not running), backprobe the temperature input wire at the heated seat switch or control module and measure voltage. If the input is at battery voltage (~12 V), proceed to isolate the short.
- Disconnect the heated seat switch/module connector. Re-measure the voltage on the harness side of the temperature input. If voltage remains at battery, the short is downstream (vehicle wiring or splice). If voltage drops, the short is internal to the switch/module.
- If harness side shows battery voltage, use a fused jumper or an appropriate fused test light and continuity meter to trace continuity between the temperature input wire and the battery positive; inspect inline splices, connectors, and nearby circuits that share routing.
- With the sensor/switch disconnected, measure resistance of the temperature sensor (if accessible) at ambient and compare to specification or check for open/short (infinite or near-zero resistance indicates fault).
- Wiggle test the harness while monitoring the input voltage for intermittent shorts. Check areas where the harness passes through body holes, under the seat frame, and near seat heaters or power feeds.
- Repair the faulted wiring (replace damaged section, repair connector, clean/correct pin position) or replace the faulty seat switch/module or temperature sensor as indicated by tests. Use OEM repair procedures and protect repaired wiring from chafing.
- After repair, clear codes, reconnect battery if disconnected, verify proper temperature input voltages and thermistor behavior with scan tool, and perform a functional test of the heated seat system. Confirm no repeat DTCs after cycling ignition and short test drive.
Likely causes
- Pinched/damaged harness under the seat with insulation pierced and touching a battery feed
- Connector terminal pushed into adjacent 12V pin or foreign conductive debris in connector
- Faulty seat switch or temperature sensor with internal short to supply
- Poorly repaired splice or butt connector that has shorted to a 12V circuit
Fault status
Status
B1918 — Heated Seat Switch temperature input shorted to battery (signal at battery voltage).
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
HTML Workshop Manuals AI manual library for HUMMER Click to show available manuals 8
HUMMER 2010 Hummer H3 Alpha
HTML ManualHUMMER 2010 Hummer H3 Base
HTML ManualHUMMER 2010 Hummer H3 Base
HTML ManualHUMMER 2010 Hummer H3 L5-3 3.7L
HTML ManualHUMMER 2010 Hummer H3 V8-5 V8-5.3L
HTML ManualHUMMER 2010 Hummer H3T Alpha
HTML ManualHUMMER 2010 Hummer H3T Base
HTML ManualHUMMER 2010 Hummer H3T Base
HTML ManualYour 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