How to retrofit/ make your own loom for heated electric seats

[dauphin]

Originally Posted by Briodyjl01

Is there a how to guide to just for the heated seats as someone has fitted the heated seats but they have manual adjustment.

I’m sure it will be very much the same, but slightly less wiring.

If you have the underseat plugs that go with the seats, just connect up the wires attached to those plugs, using the same instructions as above. Where those wires don’t exist on the manual adjustment seat plugs, ignore those parts of the instructions.
If you don’t have the plugs and are going to use the plugs from an electric seat adjustment car, look at the description above for what each wire is for on the passenger seat. From that description it’s fairly clear that pins 1,2 and 3 will still be required for the heated seats. The only question is over pin 5 and I’m not sure if that would be needed or not. But if you look at the underside of the seats, you can probably see if pin 5 on the receptacle side of the connector is actually connected to anything - if it’s not, you obviously won’t need to wire up pin 5 of the plug. If it is, or if you are not sure, you may as well wire up pin 5 anyway as per the instructions; if it turns out to be a dead end at the seat end it won’t do any harm.
Then duplicate the passenger seat wiring on the driver’s side.

[Rick-sta]

Originally Posted by dauphin

Successfully used the instructions here to get my electric seats up and running - thanks!

But I seem to have introduced a K-bus error - no indicator tell-tales, aircon “Er” reading, central locking not working, etc. As I had included the pin 6 connection to a K-bus wire behind the centre console, my first thought was that I must have made a mistake there, so I tried breaking the connection to pin 6. Unfortunately this hasn’t made any difference!

I appreciate I’m probably getting into crystal ball territory, but any ideas what I could have done wrong?? There’s been minimal disturbance to the existing wiring and I’m really not sure where to start looking.

I had a similar issue when my K-bus wire for the driver's seat had a break in it and was touching the metal bodywork under the carpet. My indicator tell tale lights stopped working as I took my K-bus feed from the LSM.

Have you tried disconnecting the K-bus wire from where you took the feed behind the centre console? If you have a break in the wire and it's shorting somewhere, disconnecting it from the seat plug won't fix the issue

[Rick-sta]

Originally Posted by Briodyjl01

Is there a how to guide to just for the heated seats as someone has fitted the heated seats but they have manual adjustment.

As above what Dauphin said, take a look at the large black 8 pin plug you have under the manual heated seats. The black plug should only be populated with 3 wires I believe on the seat side, 1 12v ignition live, 1 yellow signal wire for the heated seat switch and 1 earth per seat. Look at what pin numbers they are located in and then just follow the guide for those relevant wires

[dauphin]

Originally Posted by Rick-sta

I had a similar issue when my K-bus wire for the driver's seat had a break in it and was touching the metal bodywork under the carpet. My indicator tell tale lights stopped working as I took my K-bus feed from the LSM.

Have you tried disconnecting the K-bus wire from where you took the feed behind the centre console? If you have a break in the wire and it's shorting somewhere, disconnecting it from the seat plug won't fix the issue

Thanks Rick, but yes I did actually disconnect it from where I’d spliced it in behind the centre console. It’s a bit of a mystery at the moment - I suppose I must have disturbed a K-bus connection somewhere else, but I really can’t think how or where that might have happened.

[dauphin]

Originally Posted by dauphin

Thanks Rick, but yes I did actually disconnect it from where I’d spliced it in behind the centre console. It’s a bit of a mystery at the moment - I suppose I must have disturbed a K-bus connection somewhere else, but I really can’t think how or where that might have happened.

It’s occurred to me that I replaced the driver’s door at the same time I was fitting the electric seats. Is there any K-bus wiring going to the door - just wondering if there could be a problem with the electrical connector inside the A-pillar, or with the central locking actuator? I swapped the key-operated lock from the old door, but didn’t bother changing the actuator over.

[dauphin]

Found the problem! It was the red/white wires from pin 3 of the heated seat switches (for illumination of the switches at night). I thought I’d followed the instructions by joining these to a red/white wire behind the centre console but I must have chosen the wrong red/white wire because once I disconnected this joint the K-bus fault went away.

Photo shows where I’d joined the switch wires (removed in the photo, which shows the location of the join now covered in red insulating tape). Definitely no yellow banding on that wire, so I’m not sure why the K-bus was affected.

I can happily manage without the switch illumination - far preferable to a messed up K-bus! - but it would be good if anyone can tell me where I went wrong and how to identify a suitable sidelight circuit wire to tap into.

[Rick-sta]

Originally Posted by dauphin

Found the problem! It was the red/white wires from pin 3 of the heated seat switches (for illumination of the switches at night). I thought I’d followed the instructions by joining these to a red/white wire behind the centre console but I must have chosen the wrong red/white wire because once I disconnected this joint the K-bus fault went away.

Photo shows where I’d joined the switch wires (removed in the photo, which shows the location of the join now covered in red insulating tape). Definitely no yellow banding on that wire, so I’m not sure why the K-bus was affected.

I can happily manage without the switch illumination - far preferable to a messed up K-bus! - but it would be good if anyone can tell me where I went wrong and how to identify a suitable sidelight circuit wire to tap into.

Well done finding the issue. That red/white wire you used, where does it lead to? K-bus wires are red/white with yellow stripes, but quite often the yellow stripes can be very faded.

Maybe take the feed from the red/white wire going to the ciggy lighter, as no k-bus wire goes to there

[dauphin]

Originally Posted by Rick-sta

Well done finding the issue. That red/white wire you used, where does it lead to? K-bus wires are red/white with yellow stripes, but quite often the yellow stripes can be very faded.

Maybe take the feed from the red/white wire going to the ciggy lighter, as no k-bus wire goes to there

I think it goes to the radio Rick. I’m certain it has no yellow banding and it’s also a thicker gauge than the K-bus wires I’ve identified.

I will probably leave well alone for the time being and do without the night time switch illumination, it’s so good to have everything else back working! But if I get a rush of enthusiasm to have another go, I will try the cigar lighter feed as you suggest, thanks.

[Briodyjl01]

Hello, ive had a look under my seats and it doesnt have the electric memory bit but just the seat heaters. theres a red anbrown wire they comes from the base heater and a green/purpil and red coming from the back rest and they join to make 1 plug. the red goes from the back rest to base and the brown green/ purple goes to a small plug thats not connected to anything but i can't seem to see the green/purple on your diagram?

[Rick-sta]

Originally Posted by Briodyjl01

Hello, ive had a look under my seats and it doesnt have the electric memory bit but just the seat heaters. theres a red anbrown wire they comes from the base heater and a green/purpil and red coming from the back rest and they join to make 1 plug. the red goes from the back rest to base and the brown green/ purple goes to a small plug thats not connected to anything but i can't seem to see the green/purple on your diagram?

The wiring you are referring to is the wiring for the heated seat elements on the seat itself. My wiring diagram is for fitting the electric heated seat loom on the car side.

I'm not sure why you're missing the large black 8 pin plug under each seat.