Tests Tell Us Why Buick Seat Not Heating

Posted 10/3/2011
By Bill Siegmann

I recently received a hotline call on a 2005 Buick LeSabre. The complaint was that the heated seat was not working on the driver's side.

The technician told me the heated seat problem was intermittent. He had replaced the heated seat module before checking all power and grounds to it, prior to calling us.

The first test I suggested was to find and disconnect the gray six-way C2 connector at the heated seat module, located under the driver's seat. After the connector was disconnected, I had the technician use a digital volt/ohm meter (DVOM) to measure the resistance of the front seat heat elements between terminal A, the red wire; and terminal C, the black wire. The resistance should be less than five ohms. It checked OK. If the resistance had been higher, I would have suggested replacing the front seat heating elements.

Next, the resistance of the front seat thermistor was checked from terminal D, the gray wire, to terminal F, another gray wire. It should measure 800-11,500 ohms. It checked OK. If the resistance was not within specifications, it would indicate a defective thermistor circuit, and that the front seat heating elements would need to be replaced.

Then we double-checked for connection problems at the connector; OK, too. Knowing how common it is for heated seat elements to fail, I had him reconnect the ohmmeter between pins A and C, just as before. Next, I asked him if someone could sit on the seat while he checked for a glitch on his meter. With the meter connected and watching resistance, the person in the seat shifted his weight around on the cushion, pushed backwards into the seat back, and also knelt on the seat cushion. We were hoping to find a problem using the meter.

Next, we did the same routine while testing between pins D and F for the thermistor circuit. Finally, the ohmmeter glitched out of range, so we knew the front seat heating elements needed to be replaced.

Note: The passenger side front seat elements are designed in the same way. So if the passenger side works correctly, the known good resistance values can be tested there if needed. GM's Technical Service Bulletin No. 01-08-50-012B addresses tests and part numbers for different makes and models.

Bill Siegmann is an Identifix GM specialist. He is an ASE master and Buick service master with L1 certification.

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