I have recently purchased full leather st150 heated seats for my Mk6 zetec s. Is it possible to wire in the heated function. I have had a look and there is no fuse in the fuse box space for it. If I try and put a fuse in, it's just falls out because there is no metal connection for it. 

How would I be able to wire these up to the zetec s loom? 

Cheers 

Joe,

What I did was use a piggy back fuse holder, and use the unused F2 and F3, trailer fuseways

 

one of which is permanent, and the other switched.  I managed to use nylon cable ties to keep the holders in position, and they have not fell out yet, even after three years.  I also added an extra Accessory socket (a la Fusion Titanium) and a glove box light.

41 minutes ago, Paulkp said:

Joe,

What I did was use a piggy back fuse holder, and use the unused F2 and F3, trailer fuseways

 

 

one of which is permanent, and the other switched.  I managed to use nylon cable ties to keep the holders in position, and they have not fell out yet, even after three years.  I also added an extra Accessory socket (a la Fusion Titanium) and a glove box light.

Cheers mate, do I need a piggyback holder in each fuse holder then run the wires to the heated seats? How would I go about wiring it up under the seat. Can I not just run both of them off the switched fuse rather than the constant? Cheers 

That diagram is just how did mine, in conjunction with a few other mods.

You could just use a piggy back with suitable fuse rating and feed your switches directly, but I tend to use relays.  The F2 and F3 slots only have the one supply connection in the fuse box.

You can just about make them out in the image above.

I don't know anything about ST Seats, so cannot offer any adice about wiring, but I have connectors that enable easy disconnection so I can get the seats in and out.

I bought the Ford kit that comes with a significant amount of cabling, switches and has two seat pads per seat (back and bum!), which can be operated in series or parallel, and fitted them to the full leather seats that came in my Zetec S.

3 hours ago, Paulkp said:

That diagram is just how did mine, in conjunction with a few other mods.

You could just use a piggy back with suitable fuse rating and feed your switches directly, but I tend to use relays.  The F2 and F3 slots only have the one supply connection in the fuse box.

You can just about make them out in the image above.

I don't know anything about ST Seats, so cannot offer any adice about wiring, but I have connectors that enable easy disconnection so I can get the seats in and out.

I bought the Ford kit that comes with a significant amount of cabling, switches and has two seat pads per seat (back and bum!), which can be operated in series or parallel, and fitted them to the full leather seats that came in my Zetec S.

There are wires for the heating element under the seat but obviously the multiplug in the car doesn't have the necessary wiring for the heated seats in the zetec s. 

When you say the f2 and f3 fuses only have one supply connection, what does that mean, do you mean that only one will get the power and the other is just a switch for the ignition? I'm not brilliant with electrician wording 🤣

The OP means that in the fusebox locations F2 and F3 they only have the terminals fitted on the input side of the fuse holder, (the supply side) there is no terminal fitted in the fuse holder on the side that would be the output to the seats.

You can buy a special fuse for situations like this. It has a 'Break out wire' so that the fuse can be inserted in to the correct location (F2 or F3) and the new extra wiring that is needed for the seats can be connected directly to the fuse. See example pictures below:

 

 

1 minute ago, unofix said:

The OP means that in the fusebox locations F2 and F3 only have the terminals fitted on the input side of the fuse holder, (the supply side) there is no terminal fitted in the fuse holder on the side that would be the output to the seats.

You can buy a special fuse for situations like this. It has a 'Break out wire' so that the fuse can be inserted in to the correct location (F2 or F3) and the new extra wiring that is needed for the seats can be connected directly to the fuse. See example pictures below:

 

Ah spot on, thanks for clearing that up. I'm not brilliant with wiring so just getting some knowledge together before I attempt it 

Hi I also got heated, powered seats from a MK2.5 titanium Into my zetec. 

The powered part works fine on the zetec loom, but the wires for heating just aren't present in the cars seat connector. 

 

I plan, when I get round to it, to buy (variable) heated seat switches off eBay, put those in the centre console, then run wires down to the seat connectors from the switches. 

I will then use a fuse like the ones above to put power to those heated seat switches. 

 

I'll be watching with interest how you get on. Best of luck. 

On 6/6/2022 at 2:20 PM, unofix said:

The OP means that in the fusebox locations F2 and F3 only have the terminals fitted on the input side of the fuse holder, (the supply side) there is no terminal fitted in the fuse holder on the side that would be the output to the seats.

You can buy a special fuse for situations like this. It has a 'Break out wire' so that the fuse can be inserted in to the correct location (F2 or F3) and the new extra wiring that is needed for the seats can be connected directly to the fuse. See example pictures below:

 

 

Just a quick question, I'm think of putting a piggyback fuse into one of the switched fuses so it turns of when the engine is off. I'm going to run a live cable to both seats but have 1 wire going to the fuse all together so patch a wire from one seat to the other then to the fuse? Will this be safe/correct? Where should I put the ground wire if it needs one? I have read that you don't need a ground wire but I'm not 100% sure. Cheers 

I would advise not to connect one seat to the other as potentially each seat could draw up to 20 Amps, that would mean the cable supplying the primary seat would have to be able to carry up to 40 amps

25 minutes ago, unofix said:

I would advise not to connect one seat to the other as potentially each seat could draw up to 20 Amps, that would mean the cable supplying the primary seat would have to be able to carry up to 40 amps

Alright that's sound mate, so I will just do one piggyback fuse for each seat. Will they need a ground wire? 

The fuse used in the ST is 7.5 amps for both so will using two piggyback with one 7.5 amp fuse in each be alright? Sorry for asking loads of questions, just want to get a good idea before I start messing around with it 

Yes that will be fine. You can use any good solid bolt under the seat that is fastened to the floor for a ground (negative) connection 

8 minutes ago, unofix said:

Yes that will be fine. You can use any good solid bolt under the seat that is fastened to the floor for a ground (negative) connection 

Spot on, cheers for the help, I'm going to attempt this tomorrow and see how I get on. I think there is a bolt behind the handbrake for a ground so could tuck it under there. Thanks for the help. Just got to figure out the wires under the seat now 

I know this is probably a stupid question, if I use the F2 and F3 fuse locations, if one is constant, will that draw power even if the heated seat button is switched off? So if the heated seat button is turned off and ignition is off, will it drain the battery? 

Managed to get a photo of the wiring underneath the seat. The purple wiring comes from the multiplug into the switch on the seat which then comes out as a black wire Into the connector in the middle of the photo and then up into the seat so I'm guessing that is the live wire. The black wire that goes from the multiplug to the connector must be the ground? So If I connect the live with the purple and ground with the black wire from the multiplug then that should be all good? 

I just noticed that the circuit diagram posted above for F2 and F3 shows that they would both be live all the time as they are both directly connected to the battery. However @Paulkp has said one of them is switched via the ignition so something doesn't match up.

Even if the supply is live all the time the seats will not draw power unless switched on but I would say that you need the supply to go via a relay so that the seats can not be left turned on when the ignition is off, or else you will end up with a very flat battery if you forget to switch them off.

6 minutes ago, unofix said:

I just noticed that the circuit diagram posted above for F2 and F3 shows that they would both be live all the time as they are both directly connected to the battery. However @Paulkp has said one of them is switched via the ignition so something doesn't match up.

Even if the supply is live all the time the seats will not draw power unless switched on but I would say that you need the supply to go via a relay so that the seats can not be left turned on when the ignition is off, or else you will end up with a very flat battery if you forget to switch them off.

I'm going to put the piggyback fuses into ones where they are only live when the ignition is on so the heated screen ones for example. 

Like you say, I don't fancy having a flat battery so finding a fuse slot that is not live when the ignition is off is my best bet. 

I think the purple wire in the photo is the live wire as it goes from the multiplug to the switch which then has a black wire coming out of the switch Into the seat. So those 2 wires are live. The black one that comes from the multiplug into the heated seat pad must be the negative wire. 

I'm going to join the purple wire with some 14 awg wire that I have got and run that to the piggyback fuse and the join the black neutral wire with some more wire to a ground. Does that sound about right? 

Forget my last statement about F2 and F3, I was looking at the fuses in the engine bay fusebox DOH !!

Fuse F2 in the passenger fusebox is switched via the ignition and is the supply for both front seats. It seems that your seats take a lot less current than others I have dealt with in the past. Also it would seem that F2 is fed from F3 which is in fact live all the time.

1 minute ago, unofix said:

Forget my last statement about F2 and F3, I was looking at the fuses in the engine bay fusebox DOH !!

Fuse F2 in the passenger fusebox is switched via the ignition and is the supply for both front seats. It seems that your seats take a lot less current than others I have dealt with in the past. Also it would seem that F2 is fed from F3 which is in fact live all the time.

It's alright, instead of using F2 and F3 I'm going to use ones like the heated screen and window switches which are only live when the ignition is on. So I will have one piggyback in each. 

I appreciate the help aswell 👍😁

Would that 10mm bolt be a good earth point. It holds the seat base onto the seat frame. It's not painted and is all metal? 

I've been swimming so missed all this !

I earthed mine direct to chassis, using an earth point under the centre console, probably E13.  If you are disconnecting an earth point, I would first disconnect the battery, especially as E13 is also used by the SRS.  I would not use a bolt on the seat itself for earth return.  

Use a pair of cables direct to each of your seats from your supply point. and use a highish current rating cable to reduce losses.  If you only used one cable, the losses are squared.  Use similar thick cables for your earth/ground points.

The 60A F6/F feeds the common of the Ignition relay K79, which then provides the supply to F2 when the ignition is on.  This energises the coil of my seat relay and also directly feeds my additional accessory socket.  So I have used a 7.5A in the piggy back.

The 60A F7/G feeds (amongst other things) F3, the supply to the common of my seat relay, and then I have two cables from the normally open contact of that relay to the individual seats.

F3 is rated at 15A, iaw the XVision Kit I used.  In Low, each seat uses 2.3A and in High, 7.5A, so max nominal rated current is 15A.  The seat switches select High, Low and Off !

15A is max rating for 14AWG I think, and a fuse is there to protect the wiring, not the load, 

Fuses do not blow at the "Rated" current. IIRC, they appear to blow blow instantaneously at 2x rated current, but they do take a finite time for the filament to heat up and rupture.

F101 is my fuse for the glove box.

Unfortunately the "Blobs" on the diagram to show joints do not show up very well !  But I did originally only do this for my benefit !

 

 

If both seats are rated at 7.5 amp fuse for both combined, should I use 7.5 amp in each piggyback or get one around 4 amps for each piggyback?. I will ground it around the handbrake lever bolts. 

 

Not knowing what the current is for your seats, my suggestion would be to use a 7.5A for each seat.

 

Right, bed time !