Heated seats - fuse keeps blowing

[greencode]

Just spent the day installing some manual heated M seats in my Z and all appeared to be going well until I tried the heated seats.

Turned on both seats with the centre console switch and the lights came on and it was seemingly pretty slow to heat up. However, I then just got back in the car and tried it again only for the lights on the switch to come on and the immediately turn off. Checked the fuses and Fuse 16 (25A) is the one that's blowing. Had a spare and it did the same thing again.

Just wondering what I should try? I presume I'll have to go through the following:

- get a load of 25A fuses!
- test by turning on the heating of one seat only to try to at least narrow the issue down to the seat.
- If I manage to find out that it's one seat in particular that's causing the blown fuse then get underneath the seat and unplug the back heating element first, just to rule that out, then unplug the heating plugin completely (is that possible? I'm sure it must be) and test the switch to see if it's the actual switch that's the issue.

Any other ideas?

 

[Smartbear]

If you could find out the resistance of the elements you could test on ohms directly on the plugs for each element (assuming the fault lies there)
On the z3 I know they were prone to breaking up if people knelt on the seats)

 

[greencode]

If you could find out the resistance of the elements you could test on ohms directly on the plugs for each element (assuming the fault lies there)
On the z3 I know they were prone to breaking up if people knelt on the seats)

Blimey, wouldn't know where to even begin :?

 

[Yorkie Z]

Maybe start by unplugging one of the seats and replace the fuse to see if it blows. If it does try the other side.

 

[greencode]

Maybe start by unplugging one of the seats and replace the fuse to see if it blows. If it does try the other side.

Yeah, that's what I'm going to do. Just ordered 25 fuses so that should give me enough for a bit of playing around with to see if I can get to the issue. I don't think it's anything too serious as on both occasions that it's blown, it's been perfectly okay to start with, I then started messing around with the car again and they blew. I have a sneaky feeling it might be the wires pressing against the seat frame under the passenger seat.

 

[Zoomer]

If you unplug the seat you will get the airbag light on I think so better to disconnect the battery , then unplug the seat heater connection from the seat base then plug the connector to other wires back. You then connect the battery and try the other seat

 

[greencode]

If you unplug the seat you will get the airbag light on I think so better to disconnect the battery , then unplug the seat heater connection from the seat base then plug the connector to other wires back. You then connect the battery and try the other seat

Thanks for this. Yep, I'm aware about the seatbelt light coming on so all good there. Just a bit of a pain when it was such a nice day today to get this all done! Oh well, once it is fixed I'll be going out in the coldest weather to fully test

 

[Mister T]

I had similar fuse related issues with the seats on my Z3, turned out to be a trapped wire under the seat base that was shorting out.

 

[greencode]

I had similar fuse related issues with the seats on my Z3, turned out to be a trapped wire under the seat base that was shorting out.

*touch wood* that's all it'll be with mine.

Will report back.

 

[aarsavage]

DIS may give you some info on the seat electrics if you have the software/cable.

Noticed mine had an old 'under voltage' error and another for the temp sensor "open circuit" from where the previous owner re-installed the stock seats incorrectly.

 

[greencode]

DIS may give you some info on the seat electrics if you have the software/cable.

Noticed mine had an old 'under voltage' error and another for the temp sensor "open circuit" from where the previous owner re-installed the stock seats incorrectly.

I don't have one of those. I'm presuming a OBD2 scanner wouldn't be able to give this kind of info?

 

[aarsavage]

DIS may give you some info on the seat electrics if you have the software/cable.

Noticed mine had an old 'under voltage' error and another for the temp sensor "open circuit" from where the previous owner re-installed the stock seats incorrectly.

I don't have one of those. I'm presuming a OBD2 scanner wouldn't be able to give this kind of info?

I'm not sure, doubt it.

 

[greencode]

Got 20 x 25A fuses today and did my first test. Raised both seats (just so there's no wires that potentially may be getting trapped) and then sat in the driver's seat with the heated seat switch on full. Worked perfectly. Will do further tests tomorrow as the weather is horrible today.

 

[greencode]

Still not sure what was causing the fuses to blow but inserted another new fuse yesterday and fully tested the seats out by putting them up and down, to see if a wire was catching under the seat, and tried just one seat heating on at a time and everything appears to be working well. I still think it's a wire under the passenger seat that may have been getting trapped. When I can face it, I think I'll remove the seats once again and tidy everything up a bit. Until then, I've got a nice warm bum