GMC Sierra Denali B1935: Heated Seat Not Working Causes & Fixes (2007-2011)

What's Unique About the 2007-2011 Gmc SIERRA DENALI

The GMT900 platform, which includes your 2007-2011 Sierra Denali, is well-known for heated seat failures. The primary reason is the design of the heating element itself; the thin wires embedded in the seat pad are prone to breaking after years of a driver getting in and out, causing an open circuit. Additionally, a secondary common failure point is the main electrical connector for the heated/cooled seat module (located under the front passenger seat), which can overheat and melt due to high current draw, affecting one or both seats. 🎬 Watch: How to repair the common melted seat module connector. This issue is so common that repair videos and forum threads specifically document the melted plastic on the power and ground pins.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Driver's side heated seat does not get warm.
• The heated seat indicator light turns on for a few seconds, then turns off by itself.
• The heated seat indicator light stays on, but no heat is produced.
• A 'Service Airbag' message appears on the dash, if the wiring damage under the seat has also affected the Passenger Presence System (PPS) wiring harness, which is routed nearby.
• In some cases, both heated seats may stop working if the shared power connector under the passenger seat has failed.

Most Likely Causes

1. Broken Driver's Seat Heating Element (Pad) 🔴 High Probability The heating element is a grid of fine wires inside the seat cushion that flexes every time you sit down. Over thousands of cycles, a wire eventually breaks, creating an open circuit. This is the most common point of failure for this specific code.
   How to confirm: Disconnect the Memory Seat Module (MSM) connector under the driver's seat. Use a multimeter to check the resistance between the pins for the seat back heater and seat bottom heater. A reading of 'OL' (Open Loop) or infinite resistance indicates a broken element. A good element should read between 3 and 12 ohms (specifically, 3.5-11.5 ohms for the cushion and 2.5-8.5 ohms for the backrest are commonly cited). Wiggling the seat while testing can expose an intermittent break.
   Typical fix: Replace the faulty heating element pad (either seat bottom or back). This requires removing the seat and the upholstery (seat cover) to access and replace the pad. Some owners have attempted to solder the broken wire, but this is often a temporary fix.
   Est. part cost: $80-$150
2. Burnt Connector at Heated Seat Module 🟡 Medium Probability The module for heated/cooled seats is located under the front passenger seat and controls both seats. Its main 12-pin power connector is not robust enough for the high current draw, causing the heavy-gauge power (Red/White) and ground (Black) pins to overheat, melt the plastic connector housing, and create a poor or open connection.
   How to confirm: Move the front passenger seat fully forward and upward. Visually inspect the large 12-pin electrical connector going into the silver control module under the seat. Look for signs of black or brown discoloration, melted plastic, or burnt pins, especially at the corners.
   Typical fix: The connector and any damaged pins must be replaced. A new connector pigtail (ACDelco PT2389 / Motorcraft WPT-928) is spliced into the harness. Some owners proactively double-up the power and ground wires into unused slots in the new connector to better distribute the load, a technique used by Ford which shared this module design.
   Est. part cost: $25-$75
3. Damaged Wiring Harness Under Seat ⚪ Low Probability The wiring harness under the driver's seat can be pinched, chafed, or cut by the seat's movement on its tracks over time. GM TSB PIT5215A specifically notes that if accessory heated seats were installed, the connectors for the back and bottom elements can be reversed, causing this code.
   How to confirm: Move the driver's seat to its highest and rearmost position. With a flashlight, visually inspect the wiring harnesses running underneath the seat for any signs of damage. Per TSB PIT5215A, check that the longer harness lead goes to the seat back and the shorter lead goes to the seat bottom.
   Typical fix: Repair the damaged section of wire with a new piece of wire, using butt connectors or solder and heat shrink tubing. Ensure the repaired harness is properly routed away from any moving parts. If connectors are reversed, swap them to their correct positions.
   Est. part cost: $5-$20

Rare But Worth Checking

• Faulty Heated Seat Module / Memory Seat Module:

Diagnosis Steps

1. Verify the symptom: Press the driver's heated seat button and observe if the light comes on and then goes out, or stays on with no heat.
2. Scan for codes: Use a scan tool capable of reading Body (B-prefix) codes to confirm B1935 is present.
3. Check Fuses: Check the fuses labeled 'MBEC 1' (50A under hood) and 'SEAT CB' (30A circuit breaker, in-cabin fuse panel) as these supply power to the system.
4. Inspect Passenger Seat Connector: Move the front passenger seat all the way forward and up. Visually inspect the large 12-pin connector on the silver control module underneath for any signs of melting or burnt pins. This is a very common failure.
5. Inspect Driver Seat Wiring: Move the driver's seat all the way up and back. Visually inspect the wiring harness underneath for any obvious signs of chafing, pinching, or breaks.
6. Test the Heating Elements: If no visual damage is found, test the elements. Disconnect the appropriate connector at the Memory Seat Module (MSM) under the driver's seat. Using a multimeter set to Ohms (Ω), measure the resistance of the seat back and seat bottom heating elements. A reading between 3-12 Ohms is good. A reading of OL (Open Loop) or MΩ (Megaohms) indicates a broken element that needs replacement. A user on Reddit provided specific pins to test on the green connector at the MSM: check resistance between pin 14 (pink) and pin 1 (purple) for the back heater, and between pin 14 (pink) and pin 11 (light green) for the bottom heater.

Parts You'll Likely Need

• Driver Seat Cushion Heating Element (OEM #23168136) — This is the most common failure point. The wires inside this pad, which is located in the seat bottom, break from normal use, causing the B1935 code. Note that this part number may apply to later models, always verify with VIN.
  Trusted brands: ACDelco (Genuine GM), Dorman (e.g., 628-040 Universal Kit)
  OEM price range: $100-$150
  Aftermarket price range: $70-$120
• Driver Seat Back Heating Element (OEM #20792749) — This element in the seat back can also fail, though slightly less common than the seat bottom. It's often replaced at the same time. This part number supersedes 15232560 and 25911156.
  Trusted brands: ACDelco (Genuine GM), Dorman
  OEM price range: $90-$140
  Aftermarket price range: $60-$100
• Heated Seat Module Connector Pigtail (OEM #ACDelco PT2389 (GM 88988313)) — If the connector under the passenger seat is melted, it must be replaced. The Ford equivalent, Motorcraft WPT-928, is identical and often used as a substitute.
  Trusted brands: ACDelco, Motorcraft, Dorman
  OEM price range: $35-$55
  Aftermarket price range: $25-$45

Related Codes That Often Appear With This One

• B2425 — This code specifically indicates a Driver Seat Heater Circuit fault and is often logged alongside B1935, confirming the issue is with the driver's seat.
• B2430 — This code indicates a Passenger Seat Heater Circuit fault. If you see this with B1935, it strongly points to a shared problem, like the burnt main connector at the heated seat module under the passenger seat.

Technical Service Bulletins (TSBs) & Recalls

• PIT5215A: Heated seat is inoperative or does not heat, may set DTCs B1935, B2180, B2425, and/or B2430. Specifically addresses reversed connectors on accessory heater installations.

Platform-Specific Known Issues

• TSB PIT5215A was issued by GM for inoperative heated seats, specifically calling out the need to inspect the accessory heated seat wiring harness for reversed connectors between the seat back and bottom elements.
• The main power connector for the heated/cooled seat module, located under the front passenger seat, is a known weak point. The high current draw for both seats is routed through single power and ground pins, which can overheat and melt the connector housing, leading to an open circuit and failure of one or both heated seats.

Mechanic-Grade Diagnostic Values

• Driver Seat Back Heating Element Resistance — expected: 2.5 - 8.5 Ohms. Failure: Reading of 'OL' (Open Loop) or infinite resistance.
• Driver Seat Cushion Heating Element Resistance — expected: 3.5 - 11.5 Ohms. Failure: Reading of 'OL' (Open Loop) or infinite resistance.
• Heated Seat NTC Signal Voltage — expected: 4.8 - 5.2 V. Failure: Voltage outside this range indicates a sensor or wiring issue.
• Heated Seat NTC Low Reference Circuit to Ground — expected: < 10 Ohms. Failure: Resistance greater than 10 Ohms indicates a poor ground connection.

Hidden / Shadow Codes Worth Checking

• B1935 Sym 0E: This specific symptom byte, when paired with B1935, authoritatively indicates a fault within the accessory heated seat system. GM TSB PIT5215A directly references this code for issues like reversed element connectors or wiring faults. (see via A professional GM-specific scan tool like a Tech2 or GDS2, which is capable of reading manufacturer-specific symptom bytes in addition to the base DTC.)

Scan Tool Commands That Help

• GM Tech2 / GDS2: Read DTCs with Symptoms — This is the first step with a professional tool. Seeing 'B1935 Sym 0E' immediately confirms the fault is in the heated seat circuit, not an airbag issue, and points towards the specific TSB diagnostic path.
• GM Tech2 / GDS2: Heated Seat Output Control (Inferred) — While not explicitly documented in search results, tools of this level typically allow technicians to command individual components (like the driver's seat heater) on and off to verify module and wiring integrity after a physical repair, without having to reassemble the entire seat.

Wiring & Ground Locations

• G303 — On the lower left 'B' pillar (the pillar behind the driver's door) in Crew Cab and Extended Cab models.. This is a shared ground point for several components, including the driver's side heated seat elements. A loose or corroded connection here can cause an intermittent or total failure of the heated seat.
• G311 — Under the driver's seat carpet, near the seat mounting points.. TSB PIT5562 identifies this as a critical ground for the Driver's Power Seat and Memory Seat functions. A poor connection here can specifically cause the Left Heated/Cooled seat to become inoperative and may set Memory Seat Module DTCs.
• X310 — The main 48-way body-to-seat harness connector under the driver's seat.. This is the primary electrical interface for the entire driver's seat. All power, ground, and data signals for the heated seat pass through this connector. A loose pin or corrosion here can cause this fault.
• Heated Seat Module Connector — Under the front PASSENGER seat, plugged into the silver heated/cooled seat control module.. This is the most common point of electrical failure. The power and ground pins for BOTH seats run through this single connector, and they are known to overheat and melt the plastic housing, causing an open circuit for either or both seats.

Real Owner Repair Stories

• FTP Speed Shop on YouTube (cited by go-parts.com) (2011 Chevrolet Suburban (GMT900 Platform)) — Heated and cooled seats were inoperative for several years.
  ❌ Tried (didn't work) The owner lived with the problem, assuming a complex or expensive repair was needed.
  ✅ What actually fixed it The power pin on the main connector to the seat control module under the passenger seat was found to be completely burnt. The fix involved replacing the connector pigtail with a Ford Motorcraft WPT-928 and modifying it to use two power and two ground wires, splitting the electrical load across unused pins in the module to prevent future overheating.

OEM Part Supersession History

• ACDelco PT2389 (GM 88988313) → Motorcraft WPT-928 (Ford 3U2Z14S411ZMB) — The Motorcraft WPT-928 is not an official supersession but is widely used as a superior replacement for the melted heated seat module connector. It is physically identical but often preferred because the pigtail includes all 12 wires, allowing for the modification of adding a second ground wire to prevent future melting—a known fix for the original's design flaw.
• 15232560, 25911156 → 20792749 — Standard part evolution for the driver's seat back heating element. The newer part number is the correct service replacement.