Electrical shutdown I have a 2004 3500 Duramax that seems to have had a short in driver heated seat. Problem now has spread to all other kinds of electrical issues. Truck loses all dash output display,radio,heater,and windows at times. It has even just shut down totally on road while driving. ABS light keeps coming on and now have to jump off to start truck.

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Does your buick have memory seats ? Are you familiar with electronically controlled systems , they have a control module ?

Heating and the cooling both don't work ? Just one seat or all seats ?
Your best bet have it checked for DTC'S - diagnostic trouble codes to start .
Climate Controlled Seat Module (CCSM) Diagnostic Trouble Code (DTC) Index DTC Description Source Action B1342 ECU Is Faulted CCSM INSTALL a new CCSM and CARRY OUT programmable module installation (PMI). REFER to Climate Controlled Seat Module . B1358 Ignition Switch or Blower Electronics Circuit Short to Ground CCSM Go To Pinpoint Test Q . B2477 Module Configuration Error CCSM This DTC indicates programmable module installation (PMI) has not been done to a newly installed module. CARRY OUT PMI. REFER to Section 418-01 . CLEAR the DTC. CARRY OUT the self-test. B2486 Climate Controlled Seat Module Voltage Out of Range CCSM DEPOWER the supplemental restraint system (SRS). REFER to Section 501-20B . DISCONNECT driver safety belt buckle pretensioner electrical connector or passenger safety belt buckle pretensioner electrical connector of the affected seat and CONNECT restraint system diagnostic tool 418-F395 to the safety belt buckle pretensioner harness connector. CONNECT the battery ground cable. CHECK circuit 294 (WH/LB) for a fault. REPAIR as needed. If okay, REFER to Section 414-01 . Once the repair is complete, DISCONNECT the restraint system diagnostic tool from the safety belt buckle pretensioner harness connector and CONNECT the safety belt buckle pretensioner connector of the affected seat. REPOWER the SRS. REFER to Section 501-20B . B2488 Thumbwheel Switch Voltage Out of Range High CCSM Go To Pinpoint Test R . B2521 Tach Circuit Failure CCSM Go To Pinpoint Test Q . B2729 Cushion Over-Temp Detected CCSM Go To Pinpoint Test S . B2730 Back Over-Temp Detected CCSM Go To Pinpoint Test S . B2731 Differential Temperature Fault CCSM Go To Pinpoint Test S . B2792 Heat Switch Short to Ground CCSM NOTE: If HEAT is pressed for greater than 20 seconds on the climate controlled seat switch, DTC B2792 will set in the CCSM.
CLEAR the DTC. If the DTC does not clear, DEPOWER the supplemental restraint system (SRS). REFER to Section 501-20B . DISCONNECT driver safety belt buckle pretensioner electrical connector or passenger safety belt buckle pretensioner electrical connector of the affected seat and CONNECT restraint system diagnostic tool 418-F395 to the safety belt buckle pretensioner harness connector. CONNECT the battery ground cable. CHECK circuit 1551 (VT/WH) for a short to ground. REPAIR as needed. If okay, INSTALL a new climate controlled seat switch. Once the repair is complete, DISCONNECT the restraint system diagnostic tool from the safety belt buckle pretensioner harness connector and CONNECT the safety belt buckle pretensioner connector of the affected seat. REPOWER the SRS. REFER to Section 501-20B . B2793 Cool Switch Short to Ground CCSM NOTE: If COOL is pressed for greater than 20 seconds on the climate controlled seat switch, DTC B2793 will set in the CCSM.
CLEAR the DTC. If the DTC does not clear, DEPOWER the supplemental restraint system (SRS). REFER to Section 501-20B . DISCONNECT driver safety belt buckle pretensioner electrical connector or passenger safety belt buckle pretensioner electrical connector of the affected seat and CONNECT restraint system diagnostic tool 418-F395 to the safety belt buckle pretensioner harness connector. CONNECT the battery ground cable. CHECK circuit 1550 (WH/OG) for a short to ground. REPAIR as needed. If okay, INSTALL a new climate controlled seat switch. Once the repair is complete, DISCONNECT the restraint system diagnostic tool from the safety belt buckle pretensioner harness connector and CONNECT the safety belt buckle pretensioner connector of the affected seat. REPOWER the SRS. REFER to Section 501-20B . U2362 UBP Invalid Data Node ID CCSM NOTE: DTC U2362 indicates a network concern, the CCSM is not the source of the fault.
CLEAR the DTC. If the DTC does not clear, REFER Section 418-01 .

Does the passenger seat stay on and heat up? If so the drivers seat heater grid (just the same as an electric blanket) is shorted or open and that causes the system to switch it self off. To replace the heating grid requires the seat cover to be removed and the grid replaced, this is best left to an automotive trim shop, they are cheaper than the dealer in fixing this kind of problem. The part will need to come from the dealer if still available.

Probably a bad switch.

If it is blowing the heated seat fuse. Pull the drivers left side seat trim back to remove the seat switch. about 2-3 inches behind the switch you will likely find the wiring is rubbing on the seat track. Wrap with electrical tape and put a piece of rubber hose over it so it doesn't rub thru again. I do think this will fix you problem. I have repaired this problem many times.
Hope this helps

See GM TSB 05-08-143-001, If you have Adjustable pedals, especially if they dont; work with the memeory buttons, but function with thier own buttons. Its the Brake Pedal Position Sensor is shorted and mesing up the seat module which controls the heaters too. My 05 Suburban had the same issue.

Heated seat control module is probably at fault . Have checked for DTC'S - diagnostic trouble codes .

your problem was the electric seat motor. I had the same thing happen on passenger side while driving,fortunately smelled smoke, looked under seat and pulled motor wire loose.

The problem is most likely caused by shorted heating grids in the seat cushion itself, kind of like the heating element in an electric blanket, very expensive to replace.

Could be that the wiring for the heater is broken, or that the heating element itself has been damaged. Has anyone knelt on the seat when reaching in to get something out of the car? Or has anyone stood on it (a child maybe)? Pressure like that can break the heaters and keep them from firing up.