S
steveball1969
Hi all,
I have had success today fixing a problem with the heated front seat. The passenger seat was fine, but the driver's seat barely had any heat at all - to the extent that I wasn't sure if it was working at all. This is on a 2011 T5.1, but I'm fairly sure this would apply to any T5 or T6.
First I checked fuse, hoping that there were two fuses for the heated seats and one had failed. No such luck, there is only one fuse, so if one of your seats is working and the other is not, you can skip this step.
Next, I had a look at the connections under the seat. For future reference this is *much* easier if you take the seat out. There are two 13mm nuts at the front (slide the seat all the way back) and two 13mm bolts at the back (slide the seat all the forward. This allows you to tilt the seat forwards and makes disconnecting the three connectors under the seat easy.
There are three connectors:
1. The yellow one relates is for the pre-tensioners on the seat belt buckle. If you disconnect this one, don't turn on your ignition until it is all connected back up again, or you will have an airbag/SRS fault and warning light to fix.
2. The 8-way connector, with only three wires is for the heated seat. The two chunkier wires are to power the heating elements and the slimmer wire is for the heat sensing thermistor in the base heating element.
3. There is a third 2-way connector - I don't know what that is for!
First, I checked for power across the two chunkier wires. When powered up, I was seeing around 11v here. Note that the engine must be running and there is a slight delay once the engine has started. Whilst this is slightly lower than I was expecting, that didn't turn out to be my problem.
Next I tested resistance across the two chunkier wires. Around 11 ohms. Looking online, I was told to expect around 1 ohm each for the seat base heating element and the seat back element. The two are wired in series within the seat, so you should see around 2 ohms total across wires under the seat. Rudimentary calcs suggest that my heater would be generating around 11W of heat. If operating as designed, it should be generating around 60W of heat.
Next I took the plastic trim panels off the seat. Near the rear left of the driver's seat, at the point where the base and back meet, there is a connector. This connects the two separate elements in series. Disconnecting this connector, I was able to measure the back element resistance - 1 ohm almost exactly and what my online search had suggested was the right value for the element. I then bridged the connector leading to the seat base element with a short loop of wire and measured the resistance of the seat base element. Around 10 ohms. That's far higher than it should be.
Next, I removed the seat base entirely from the seat frame. There are two 13mm bolts underneath and then the seat base pulls forwards and comes out of the frame. There is a bit of fiddling around to ensure that the wires come out cleanly. At this pount you must have disconnected the back heating element, but you'll have already done that for troubleshooting.
Once the seat base is out, it's time to take off the fabric cover. This is fairly easy once you've working out how it is fixed. First, there are plastic trim edges all around the base. These unclip and free the cover at the edges all the way around. You can move the edges free of the seat base by compressing the foam a bit. Then there are four metal rods that are sewn into the cover, one front and back and one each side. These sit inside grooves in the foam and are looped around additional rods embedded in the foam. You can open up the looped ends slightly and then free the four rods. Once you have done this, the whole seat cover will come away and you left with the seat base, foam and heating element.
Next I needed to remove the element from the foam. It is fixed with double-sided table on all four edges and a couple more bits in the middle. I found the tape came away quite well when warmed with a heat gun. At this point, I had the heating element free of the seat and was able to move to the kitchen table which was much warmer to work in than the garage!
The heating element consists of two layers of fabric. Sandwiched between the two layers are a zig-zag of thin wire that generate the heat. Where the power wires join the element, there are three obvious wire connections and a thermistor that senses the temperature of the element.
The next bit required some trial and error. I had to find which parts of the element had higher than expected resistance. To start with, I put a light behind the element and examined the wire carefully all the way around. I didn't see any obvious breaks.
I was then able to create a small hole in the under-side of the heating element and expose the thin wire. This is enamelled and so I needed to burn the enamelling off to measure resistance back to the connector plug. I did this is a few places, trying to find where the problem(s) were. In the end, I found two places with increased resistance. Both were exactly at the point where the element folds into the gaps in the foam. I wouldn't be at all surprised if this is a common failure point because the wire flexes here every time the seat is used. I wish I'd realised this earlier - it would have saved me some time.
I exposed around 1cm of enamelled wire at each point, burned off the enamel with a lighter, and then used plumber's flux and solder to repair the section of wire. I actually did this on all of the points of the element where I had exposed the wire. Throughout this process, I continued to measure the resistance of the element. Once I had finished, the whole element had a resistance of around 1.2 ohms.
Then to replace everything. I used some spray contact adhesive to fix the element to the foam, replaced the seat cover and re-installed the seat base in the seat frame. Make sure to re-connect the seat back element. Before re-installing the seat, I checked the overall resistance of both elements - 2.2 ohms, so I'm feeling hopeful at this point.
Re-installation of the seat was straightforward, even though I was working in the dark at this point.
A quick test confirms that the heated seat is now working well. I'm not sure how long the repair will last, but I'm hopeful that its a permanent repair. The soldered joints at the folds are much more robust than the original thin wire. If it fails again, I know that I will need to buy a replacement base element. They are available, but look to cost more than £100. The existing element is labelled with part number 7H5 963 555H. This may have been superseded with a new part number, but a VW dealer should be able to advise.
I can see that several others have had problem with the failure of one heated seat. I hope that my experience helps other people troubleshoot and perhaps fix their heated seat.
The best part - total cost to fix £0 as I had all needed bits on hand.
I have had success today fixing a problem with the heated front seat. The passenger seat was fine, but the driver's seat barely had any heat at all - to the extent that I wasn't sure if it was working at all. This is on a 2011 T5.1, but I'm fairly sure this would apply to any T5 or T6.
First I checked fuse, hoping that there were two fuses for the heated seats and one had failed. No such luck, there is only one fuse, so if one of your seats is working and the other is not, you can skip this step.
Next, I had a look at the connections under the seat. For future reference this is *much* easier if you take the seat out. There are two 13mm nuts at the front (slide the seat all the way back) and two 13mm bolts at the back (slide the seat all the forward. This allows you to tilt the seat forwards and makes disconnecting the three connectors under the seat easy.
There are three connectors:
1. The yellow one relates is for the pre-tensioners on the seat belt buckle. If you disconnect this one, don't turn on your ignition until it is all connected back up again, or you will have an airbag/SRS fault and warning light to fix.
2. The 8-way connector, with only three wires is for the heated seat. The two chunkier wires are to power the heating elements and the slimmer wire is for the heat sensing thermistor in the base heating element.
3. There is a third 2-way connector - I don't know what that is for!
First, I checked for power across the two chunkier wires. When powered up, I was seeing around 11v here. Note that the engine must be running and there is a slight delay once the engine has started. Whilst this is slightly lower than I was expecting, that didn't turn out to be my problem.
Next I tested resistance across the two chunkier wires. Around 11 ohms. Looking online, I was told to expect around 1 ohm each for the seat base heating element and the seat back element. The two are wired in series within the seat, so you should see around 2 ohms total across wires under the seat. Rudimentary calcs suggest that my heater would be generating around 11W of heat. If operating as designed, it should be generating around 60W of heat.
Next I took the plastic trim panels off the seat. Near the rear left of the driver's seat, at the point where the base and back meet, there is a connector. This connects the two separate elements in series. Disconnecting this connector, I was able to measure the back element resistance - 1 ohm almost exactly and what my online search had suggested was the right value for the element. I then bridged the connector leading to the seat base element with a short loop of wire and measured the resistance of the seat base element. Around 10 ohms. That's far higher than it should be.
Next, I removed the seat base entirely from the seat frame. There are two 13mm bolts underneath and then the seat base pulls forwards and comes out of the frame. There is a bit of fiddling around to ensure that the wires come out cleanly. At this pount you must have disconnected the back heating element, but you'll have already done that for troubleshooting.
Once the seat base is out, it's time to take off the fabric cover. This is fairly easy once you've working out how it is fixed. First, there are plastic trim edges all around the base. These unclip and free the cover at the edges all the way around. You can move the edges free of the seat base by compressing the foam a bit. Then there are four metal rods that are sewn into the cover, one front and back and one each side. These sit inside grooves in the foam and are looped around additional rods embedded in the foam. You can open up the looped ends slightly and then free the four rods. Once you have done this, the whole seat cover will come away and you left with the seat base, foam and heating element.
Next I needed to remove the element from the foam. It is fixed with double-sided table on all four edges and a couple more bits in the middle. I found the tape came away quite well when warmed with a heat gun. At this point, I had the heating element free of the seat and was able to move to the kitchen table which was much warmer to work in than the garage!
The heating element consists of two layers of fabric. Sandwiched between the two layers are a zig-zag of thin wire that generate the heat. Where the power wires join the element, there are three obvious wire connections and a thermistor that senses the temperature of the element.
The next bit required some trial and error. I had to find which parts of the element had higher than expected resistance. To start with, I put a light behind the element and examined the wire carefully all the way around. I didn't see any obvious breaks.
I was then able to create a small hole in the under-side of the heating element and expose the thin wire. This is enamelled and so I needed to burn the enamelling off to measure resistance back to the connector plug. I did this is a few places, trying to find where the problem(s) were. In the end, I found two places with increased resistance. Both were exactly at the point where the element folds into the gaps in the foam. I wouldn't be at all surprised if this is a common failure point because the wire flexes here every time the seat is used. I wish I'd realised this earlier - it would have saved me some time.
I exposed around 1cm of enamelled wire at each point, burned off the enamel with a lighter, and then used plumber's flux and solder to repair the section of wire. I actually did this on all of the points of the element where I had exposed the wire. Throughout this process, I continued to measure the resistance of the element. Once I had finished, the whole element had a resistance of around 1.2 ohms.
Then to replace everything. I used some spray contact adhesive to fix the element to the foam, replaced the seat cover and re-installed the seat base in the seat frame. Make sure to re-connect the seat back element. Before re-installing the seat, I checked the overall resistance of both elements - 2.2 ohms, so I'm feeling hopeful at this point.
Re-installation of the seat was straightforward, even though I was working in the dark at this point.
A quick test confirms that the heated seat is now working well. I'm not sure how long the repair will last, but I'm hopeful that its a permanent repair. The soldered joints at the folds are much more robust than the original thin wire. If it fails again, I know that I will need to buy a replacement base element. They are available, but look to cost more than £100. The existing element is labelled with part number 7H5 963 555H. This may have been superseded with a new part number, but a VW dealer should be able to advise.
I can see that several others have had problem with the failure of one heated seat. I hope that my experience helps other people troubleshoot and perhaps fix their heated seat.
The best part - total cost to fix £0 as I had all needed bits on hand.
