2006 uplander heated seats

[sb68]

My driver and passenger heated seats stopped working. when i press the button, both lights on the panel come on for an instant and then go out. Same for drivers side and passenger side both. they were both working fine and all of a sudden both started doing this. anyone run across this particular problem or know what may be causing it? Thanks.

[Tech II]

Do the seat modules under each seat click when you operate each switch?

[sb68]

both lights beside each switch light at the same time for a second when the switch is pressed, but i dont hear any relay under either seat, the fuse is good

[Tech II]

If you look under neath each seat, you will see something like a pack of cigarettes, with a wire harness going to it....this is usually the heated seat module......

Not easy diagnosis...a Tech II scan tool is needed......first each heated seat switch is part of the HVAC control module....when you press a button for hi or lo, this sends a Class II serial data signal to the BCM, Body Control Module, which in turn grounds the heated seat relay in the module, sending power to the heated seat elements......neither system has anything in common, outside of the heated seats fuse #13(20A), and the BCM.....

If both went at the SAME TIME(both modules/relays would not go at the same time), and it is not the fuse, then unfortunately, you could have a BCM problem......like I said, only a Tech II scan tool, will inform the tech, if the BCM is receiving a signal from the switches, and then If there is a Body code set(most scan tools and code readers can't read "B" codes)......

BCM's are expensive, and usually have to be programmed when installed.....so diagnosis is critical, that a BCM is not erroneously replaced....