Heated seats will not stay on

Hi,

If they both started having the same problem at the same time, I suspect the circuit breaker is weak and may need to be replaced. There is a 30 amp circuit breaker under the dash. The idea that it runs for 20 seconds and then turns off, either the CB is bad, the switch can't handle the load anymore, or we have a short.

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If you look at pic 1, it shows a portion of the wiring schematic. I circled the power supply and pic 2 shows the circuit breaker location in the relay block.

Check to see if the relay is getting extremely hot when the seats are on. If it is, try replacing it. If it doesn't, let me know.

Take care,
Joe

Hi,

Okay, if the circuit breaker is kicking, then here is what I want you to try. Disconnect one seat at a time and try the opposite seat to see if it still happens. Hopefully, it will narrow things down.

If you can determine it to be one specific seat, disconnect it and check the resistance between the power supply wire (disconnected from power) and ground. Let's see if there is a short to ground or if there is extensive resistance in the component.

Joe

Hi,

The manual isn't providing me with the resistance specs. It is simply providing diagnostics for two specific diagnostic trouble codes. B2425 and B3941. The 3941 is actually listed under a technical service bulleting for an inoperative seat heater. But, it is not all the time.

Is it possible for you to scan the vehicle's modules to see if there are codes specific to this issue?

Here is a video showing how it's done:

https://youtu.be/InIlnsjOVFA

Without knowing the specs as far as resistance, this is the only way I would know how to diagnose it. I'm not sure why it isn't provided.

Let me know.
Joe

Hi,

Unplugging the seat adjuster is likely to cause the heater not to work. To disconnect it would require disconnecting the seat module. I will tell you that I feel you are going in the right direction. However, if both seats failed at the same time, then it's unlikely to be an element. I say that simply because for both to fail at the same time would be odd. Here are the components related to the circuit:

HEATED SEAT COMPONENTS
The heated seat system consists of the following components:
- Driver and passenger heated seat switches
- Driver and passenger seat back heater elements
- Driver and passenger seat cushion heater elements
- Driver and passenger seat back temperature sensors
- Driver seat module
- Driver door module
- Passenger door module

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If you find it is the element which is bad, here are the directions for replacement. The attached pics correlate with the directions.

2003 GMC Truck K 1500 Yukon XL 4WD V8-6.0L VIN U
Seat Back Heater Element Replacement - Front
Vehicle Body and Frame Seats Seat Temperature Element Service and Repair Removal and Replacement Seat Back Heater Element Replacement - Front
SEAT BACK HEATER ELEMENT REPLACEMENT - FRONT
SEAT BACK HEATER ELEMENT REPLACEMENT - FRONT

REMOVAL PROCEDURE
1. Remove the seat from the vehicle.
2. Remove the seat back trim cover.

Pic 1

3. Peel the seat back heater off the foam pad.
4. Disconnect the seat back heater harness.

INSTALLATION PROCEDURE

pic 2

1. Connect the seat back heater harness.
2. Install the seat back heater.
3. Install the seat back trim cover.
4. Install the seat in the vehicle.

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2003 GMC Truck K 1500 Yukon XL 4WD V8-6.0L VIN U
Seat Cushion Heater Element Replacement - Front
Vehicle Body and Frame Seats Seat Temperature Element Service and Repair Removal and Replacement Seat Cushion Heater Element Replacement - Front
SEAT CUSHION HEATER ELEMENT REPLACEMENT - FRONT
SEAT CUSHION HEATER ELEMENT REPLACEMENT - FRONT

REMOVAL PROCEDURE
1. Remove the seat trim panel.

CAUTION: If the passenger seat cushion foam is damaged when you remove the heater element, replace the passenger pressence system in order to prevent personal injury.

2. Remove the seat cushion trim cover.

Pic 3

3. Peel the seat cushion heater off of the pad.
4. Disconnect the seat cushion heater wiring harness.

INSTALLATION PROCEDURE
1. Replace the inflatable restraint passenger presence system if the passenger seat cushion foam is damaged.

Pic 4

3. Install the seat cushion heater.
4. Install the seat cushion trim cover.
5. Install the seat trim panel.
6. Re-zero the inflatable restraint passenger presence system for the front passenger seat.

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Let me know if I can help.

Joe

Hi,

The idea that it is turning on and then turning itself off indicates to me that one of the electrical components can't handle the load. You did check the circuit breaker, correct? Also, you may need to check at the switch itself to see if you lose power to the switch or if power is lost after the switch. Over the years, I have seen switches that just can no longer handle a load.

Let me know.

Joe

Hi,

You are very welcome, Eric. I'm glad you got it working. To be honest, like you, I've always had good luck with Dorman parts, and the ones online, well. Let's just say not too much. LOL

You take care and feel free to come back anytime in the future if you have questions. You're always welcome.

Have a good Christmas,

Joe