rattlenbang
Well-known member
So I had a dead passenger seat heater so I swapped the driver's seat switch over and it worked so it definitely was the switch. But when I returned the switch to the driver's seat, it wasn't working. Checked all voltages and they are okay, so the simple act of moving it around, plugging and unplugging fried it.
Lots of used around, but with the same hours as mine, or more, don't want to go that route. Not exactly cheap new, either. So I decided to take the switch apart to see what was what - they just pop apart - And think I might have figured out what the problem is. Unlike how most people think these work, they operate by an oscillator with a variable pulse width. Depending on the control setting and the thermistor feedback, the width of the pulse and therefore energy fed into the heating coils is adjusted. Higher control setting and colder thermistor gives greater pulse width and more heat, lower the control, less pulse width, less heat. Leave it to VW to make it complicated.
Now in most circuits the output control carries most of the load, gets hottest and breaks down the quickest. The output control is a MOSFET power switch 6133D. There's no output at all from that component. FYI MOSFETS are very sensitive to static and such, which is likely why mine popped plugging and unplugging it.
It's possible that another part of the circuit is fried, but I'd be willing to bet that this 6133D is toast. They're dirt cheap, just a couple of bucks and if this is the fix, you should be starting with equivalent to a new switch. I've got two on order that should come in in a few days. They are easy to replace with a small soldering iron even though it's a surface mount component, because it's so big. Only 4 leads.
I'll update this when I confirm. Here's hoping.
Lots of used around, but with the same hours as mine, or more, don't want to go that route. Not exactly cheap new, either. So I decided to take the switch apart to see what was what - they just pop apart - And think I might have figured out what the problem is. Unlike how most people think these work, they operate by an oscillator with a variable pulse width. Depending on the control setting and the thermistor feedback, the width of the pulse and therefore energy fed into the heating coils is adjusted. Higher control setting and colder thermistor gives greater pulse width and more heat, lower the control, less pulse width, less heat. Leave it to VW to make it complicated.
Now in most circuits the output control carries most of the load, gets hottest and breaks down the quickest. The output control is a MOSFET power switch 6133D. There's no output at all from that component. FYI MOSFETS are very sensitive to static and such, which is likely why mine popped plugging and unplugging it.
It's possible that another part of the circuit is fried, but I'd be willing to bet that this 6133D is toast. They're dirt cheap, just a couple of bucks and if this is the fix, you should be starting with equivalent to a new switch. I've got two on order that should come in in a few days. They are easy to replace with a small soldering iron even though it's a surface mount component, because it's so big. Only 4 leads.
I'll update this when I confirm. Here's hoping.
