Avensis Heated Seat Install

[Guest]

The parts came today! Monday and Tuesday I'll be cursing heaven and earth as I deal with god knows how many hog-clips / ring clips and complicated upholstery.. but the result will be something on my car wish list for years. Heated seats. In time for the winter. 

I ordered them last year then returned them as I wasn't sure I'd be able to do a decent job on the Avensis (DS3 was much simpler in a lot of ways). Now I'm ready to give it a go.

The Plan: 

1. Take out the seats. Unravel the clips. And as many hog ring clips as my Avensis seats have (no idea yet - hard to guess) to be able to slide and securely get them in. 
2. Make the cuts around the clips in its way and insulate the edges with electrical tape. 
3. Find the 12v wire under the centre console and solder in the power line / earth nearby. This guarantees a cut off when the car is off. That's where I'll be taking power from. I'm not sure anyone on here would be familiar enough to advise if the heated seat fuse reserved for the Excel models might have power to it but if you can make an educated guess or confirm I'd be eternally grateful.
4. Reinstall the seats.
5. Drill the hole in the centre console (see pic). I went for the three touch buttons. In the future if possible I'd love to get the proper piece from an old Excel Avensis and wire it up to the factory switches, but I'm not sure if they're setup differently to go through a computer control system or not - so hesitant to spend the money on those parts from Toyota or a scrap yard. 
6. Hope that it works!!!!

 

That's the game plan. Any tips, wisdom or things I should be aware of? 

I will take as many photos as possible and share as much as I can on here for anyone down the line looking to do the same with their Avensis. Or other Toyota model since there will likely be similarities in the challenge. Working with those clips is like battling with the devil himself... It was on the DS3 anyway. Hopefully this all goes smoothly and I don't butcher the expensive to replace interior trim parts. 

 

[Guest]

I found this guide from Toyota. However it’s for the previous Avensis model. Should be useful in taking apart the seat upholstery. 
 

wish such a kit existed for my model. Different part for the dash but other than that… I wonder if I could order this then get the switches for my car from a scrapyard.. hmm 

https://www.toyota-tech.eu/aimuploads/50ed86e3-bf8c-4584-94c0-f8373bfb5a84/Avensis_LHD_Seat_Heaters_PZ457_T0311_00_AIM_002_308_1.pdf

[Derek.w]

Have a mobile upholsterer sort out the seat and you sort out the switch fittings hopfully you be ready for when he turns up.

He have the tools & parts to replace the hog rings after cutting them off.

[Guest]

So I’ve found out the third blue wire should be wired to an ‘ACC’ - does anybody know what a few examples of these circuits would be on my Avensis? 🙂 

[Oisin]

10 minutes ago, SB1500 said:

So I’ve found out the third blue wire should be wired to an ‘ACC’ - does anybody know what a few examples of these circuits would be on my Avensis? 🙂 

ACC is accessory, which is the first key position.  In this position, the radio, cigarette lighter, etc. will have power.  Turn your key to the ACC position and see what has power.

[Guest]

19 hours ago, Oisin said:

ACC is accessory, which is the first key position.  In this position, the radio, cigarette lighter, etc. will have power.  Turn your key to the ACC position and see what has power.

I'm aware I'm probably mis-interpreting this / not understanding something simple, but do I need to wire this to one of the wires for the radio / cigarette lighter etc?   This is in addition to the red (positive) and black (earth) which I'm planning to connect. Then the blue will be a third cable, soldering / splicing into.. what? (that's the bit I'm stuck on)

[Guest]

Day 1 - First Seat

Four 14mm bolts, under plastic covers to get the seat out. 

Gently remove the airbag / seat sensor cables from underneath. 

The seat prior to being violated...

Mid way through...

First seat done...  

It was a little strange driving to pick up a pizza after with one seat missing... 

 

I'll post more tomorrow. 

I've still got to remove the centre console / dash, do the wiring and drill / place the switches. 

INSTRUCTIONS EXIST FROM TOYOTA - Attached

An official kit was sold for fitting at a dealership for the 2012-2015 Avensis. Unfortunately, even if you can get a hold of it, it won't work on the final 2015-2018 model. Not just the physical fascia / trim pieces and switches (as they could theoretically be bought from Toyota from Excel models of this final Avensis interior) but the seat differences.

 

Challenges so far:

• Toyota seats don't seem to use the metal, hog ring clips most other cars I've seen be fitted with these have. Instead are little green plastic V shapes that hold a stitched on plastic line. They are incredibly difficult to remove, so much so, two hands of force won't do it, and if you do you risk ripping the sponge before detaching them. You need a small screwdriver for leverage and gently pry them to pop out. They are worth it as they make it 10x easier popping them back in on the refitting. 
• Each 'ridge' line holding the trim in as a result of the above is a fabric tab that spans the width of the seats centre panel / top. In order to get around this, cut the edges of the fabric only, leaving the little plastic line fully in tact. Then, cut a thin line across the gap spaces on your heating pad to pop this through.
• Finally, and most importantly. If you want to attempt this, get pads with some breaks in them!!! Previously, I used pads with a continuous carbon fibre element pattern. Whilst you could cut these in certain ways for hog ring clips, with the Toyota design having a tab from left to right, this would make it difficult to cut without messing up the element. ASK for pads with GAPS so that it's easy to position them in line with the ridge on your seats, and enough for you to slide a gap to stuff them through without interfering to the element. it is sheer luck that I got a set like this, as I didn't know I'd need them until I saw how Toyota builds the seats. I ordered a spare kit for parts and those pads are not this kind. 
• Unlike the instructions state, they moved to a 15mm bolt on one side of the chairs bolts. Just have one handy beside your 14mm socket for that. 
• The pull tab clips (with the finger hole) around the back broke on me. I think I will be fine without them but take care removing them. I reckon with age, they are brittle and will break anyway, but try your best.

 

More to come tomorrow...

- Other seat pad installation 

- Removing centre console 

- Wiring it all in 

- Drilling / fitting the 3 level switches near the gearstick 

Official Heated Seat Installation - Toyota Avensis.pdf

[2009joe]

i bought the heated seats from lidal ones  that plug into the cig lighter in my center console and i have seat covers on my front seats so it covers the heated seats they are a good job in a cold morning thats for sure shane . i was going to go down your way but there was alot of work in that for me to do .i see online a guy using fabric glue to stick the heated seats to the sponge of the seats to stop it moving 

[Guest]

Here's the photos from Day 2. Proud to say it's been a success! 🙂

Had to strip the car down quite a bit... and the electrics weren't straightforward. Issue one, each kit is different. Issue two, none of the sellers can communicate very well in English, so their instructions aren't the clearest.  The second kit I ordered (in case the first didn't come this week) has four cables, the one I fitted has three... 

Red Cable: 12v Live (thick one that's only on when the car is on). Comes with an inline 15amp fuse. I connected this to an unknown blue, thick wire in the loom exposed by the drivers footwell / earth/ground point. 

Black Cable: Earth/Ground. I used the earth point at the drivers (right side) footwell near the door. 

Blue: Also a 12v Live, but this one was connected to the Live from the cigarette lighter socket. Much thinner. We added a small fuse in line here too. Just in case. 

My Theory:

If you just connect the red and black, nothing happens. Switches don't work, pads don't heat. My theory is that the blue powers the switch and control side of the unit. This then, when set to 'ON' will draw a heavier / stronger power load from the red cable to heat the elements/pads. This means if you hook your red cable up to a permanent live, or directly on the Battery, you don't need to worry about it sucking power constantly or having the heated seats operated/left on when your car is off as it requires the approval of the switch (powered by the 12v cigarette socket, only on during the car being on intentionally).  

This seems to vary depending on which switch style you order - If you want my help or the info above to work, opt for the round or square 'three touch' buttons (see pic).  The second kit I ordered has the same size round, but 'three position' light switch like switch, similar to the ones on the latest Corolla, except in the tiny little circle size of my buttons. They have a single LED which goes green or red for 'high' and 'low'. They must be the original, most common, cheap and popular option as I seen those in all the YouTube tutorials. 

The Toyota Guidance

Above I attached the Toyota guide for the 2009-2015 Avensis where they sold the genuine kit. If you own this model, I'd strongly recommend that. It has a loom which clicks right into the existing system easily (slipping in a pin, using existing earth points etc and working via the cars fuse board / safety systems). I reckon that's superior, and it comes with the fascia parts you'll need. Toyota Direct Parts still lists the Rav4 version, if you ask them and your dealer you might get one at a lower cost now as I'm sure they weren't best sellers and if still in stock, probably clearance items?  

1WW / 2WW Avensis Differences

Despite being 95% the same car to look at, the electrical system is quite, quite different. Things aren't always in the same spot. The seats in the guide are even slightly different, with one bolt size different and things like lumbar support not mentioned at all in the guidance (aimed at the older models). The old seat base was also different and more accommodating of pads, whereas the 1WW/2WW versions have more ridges meaning you need to cut the pads. Thankfully as Toyota uses plastic (not metal) clips it's a bit handier. 

[Guest]

Instructions

You'll need:

• A socket set
• Heated seat kit (3 push round/square button kind) single loom (not two single kits)
• Pliers (long nose and normal) 
• Scalpel (for cutting seat foam / pads with precision) 
• A workbench (for putting seats on / moving them around)
• Starhead and flathead screwdriver 
• Drill bit to match switches 
• Soldering iron / solder / that other tin of stuff*
• Spare wire to extend the heated seat kits wires

 

How-To

1. Remove your front seats: four 14mm bolts under pop off plastic covers. Move them to the forward most position to make it easier to remove, and remove head rests. Before lifting out, tilt back and remove the wires underneath for the airbag / electrics / occupancy sensor. 
2. Follow the Toyota guidance for removing the upholstery and side plastic panels. You'll need a star head screwdriver, each side has two screws, one at the back and side. You'll need to pop off the adjustment handles to get access to the screws. The height adjuster has a pop off panel and two further screws, don't try to pull it off. The lumbar support switch has two screws best to be removed as well. The seatbelt part hangs off, just keep that in mind when moving the seat. 
3. With the bottom base off, move it away from the main assembly. Pull back the upholstery being mindful of the green V clips. You will need more than two hands strength to pull these out, and when you do it, they will rip off.. use a small flat head screwdriver to wedge out the lines along the upholstery. You might bend them, but you can bend them back before refitting. You should get the upholstery off completely. 
4. Place your pad on the sponge. With the wire DOWN/FACING THE FLOOR, there is a hole in the foam - use this. Centre the pad. Try to align the little blank sections of your pad with the ridges in the sponge. This is where you'll be making a cut - stay between the double sided tape on your pad as any cuts to the edges will render the element useless beyond that point.  
5. The Avensis upholstery has these fabric tabs along the width of the upholstery stitched seams. These hold a plastic line which pops into the green V clips to keep it all tight and well fitting. You'll need to cut the sides of the fabric tab, this will allow you to squeeze the plastic line through the cut in your heating pad, with the plastic line able to connect into all of its clips, it sits through the line in your pad. This is an important Toyota specific adjustment you need to make to complete this job.
6. Cut a small cut out for the THERMOSTAT (fat bit) inside the pad to sit in so it doesn't poke out / become uncomfortable inside the seat. I used a scalpel as it was most precise. It can look a bit messy, nobody will see it. 
7. Ensuring your pad is straight, refit the upholstery using the clips as guidance. Ensure the main wire is down through that hole in the sponge. Peel the double sides tape prior to the refitting of the upholstery. 
8. Referring back to the Toyota guide, over at the seat assembly / rear back rest, move the fabric parts that enable you to pull up the upholstery. This pad can sit much lower, trim your pad along the top so you have about 1-2cm of non element as border. Align the top of this with the ridge on the foam - this is as far as you'll have been able to pull the upholstery up to, and don't need to pull any further. Hold the pad in place, with the double sided tape peeled and allow the bottom of the pad to wrap around the bottom of the backrest. 
9. Begin reassembling the seat according to the Toyota guidance. 
10. CAR ELECTRICS
11. Strip apart your interior. Starting with the driver side / doors bottom edge plastic trim - the long piece. Pull it up, it pops off. Then the adjacent part, more forward / corner piece of plastic trim. It has one bolt (though mines was missing) then it pulls off.  Next, two screws under the drivers footwell to remove that piece. It's the bit right above the pedals. Next, the two gun metal grey trim pieces on the centre console (both sides). Pull off the soft touch 'V' shape surround around your cupholder trim. Pull off the front two trim pieces (both sides), the front most side of the centre console. Then the part behind it (both sides).  Inside your centre console box, lift the inserts out. Unbolt the three bolts (10mm if I remember right). Pull off the trim piece behind the centre console (its back facing the back seat). Screw off the gear knob until it comes off. Gently pull the phone holder trim up / cupholder gun metal grey trim / gear gator piece gently. There are two finger plastic clips on the phone holder trim to remove. The trim should now come off. 
12. Drill your holes on the trim piece similar to mine. I can't remember the drill bit size (sorry) but it's the size of the back of the switches. Use a file to round this off / trim as needed to get the switches to fit without being jammed down. If they're clicky and upright, you've done it right. 
13. Whilst everything is pulled out, solder in your cables: blue to cigarette lighter live, black under the carpet to the driver footwell ground / earth point, red to the blue cable you'll see in the loom cable tied to the cars body near the earth point on the body / footwell side.  
14. Position the heated seat control box under the metal brace which lives inside the centre console / behind the gear stick mechanism area. Tuck in the spare length of the pad wires under the other metal brace which supports the centre console storage area. 
15. Ensure the cables have length / reach where they're meant to:  red / black under the carpet and out along the side to the earth point / loom.  Each pad connection: out the sides that will come out from under the centre console. Ensure the little wires for each switch aren't held under anything and will be able to go up to reach the switches in their position on the gear gator / cupholder trim piece. 
16. Re assemble the inside / trim. 
17. Refit your seats connecting everything up. 
18. Give it a spin! 

For all the work, this is all you'll notice different. That, and the beautiful, beautiful feeling of fast head on demand. 

[2009joe]

6 hours ago, SB1500 said:

Instructions

You'll need:

• A socket set
• Heated seat kit (3 push round/square button kind) single loom (not two single kits)
• Pliers (long nose and normal) 
• Scalpel (for cutting seat foam / pads with precision) 
• A workbench (for putting seats on / moving them around)
• Starhead and flathead screwdriver 
• Drill bit to match switches 
• Soldering iron / solder / that other tin of stuff*
• Spare wire to extend the heated seat kits wires

 

How-To

1. Remove your front seats: four 14mm bolts under pop off plastic covers. Move them to the forward most position to make it easier to remove, and remove head rests. Before lifting out, tilt back and remove the wires underneath for the airbag / electrics / occupancy sensor. 
2. Follow the Toyota guidance for removing the upholstery and side plastic panels. You'll need a star head screwdriver, each side has two screws, one at the back and side. You'll need to pop off the adjustment handles to get access to the screws. The height adjuster has a pop off panel and two further screws, don't try to pull it off. The lumbar support switch has two screws best to be removed as well. The seatbelt part hangs off, just keep that in mind when moving the seat. 
3. With the bottom base off, move it away from the main assembly. Pull back the upholstery being mindful of the green V clips. You will need more than two hands strength to pull these out, and when you do it, they will rip off.. use a small flat head screwdriver to wedge out the lines along the upholstery. You might bend them, but you can bend them back before refitting. You should get the upholstery off completely. 
4. Place your pad on the sponge. With the wire DOWN/FACING THE FLOOR, there is a hole in the foam - use this. Centre the pad. Try to align the little blank sections of your pad with the ridges in the sponge. This is where you'll be making a cut - stay between the double sided tape on your pad as any cuts to the edges will render the element useless beyond that point.  
5. The Avensis upholstery has these fabric tabs along the width of the upholstery stitched seams. These hold a plastic line which pops into the green V clips to keep it all tight and well fitting. You'll need to cut the sides of the fabric tab, this will allow you to squeeze the plastic line through the cut in your heating pad, with the plastic line able to connect into all of its clips, it sits through the line in your pad. This is an important Toyota specific adjustment you need to make to complete this job.
6. Cut a small cut out for the THERMOSTAT (fat bit) inside the pad to sit in so it doesn't poke out / become uncomfortable inside the seat. I used a scalpel as it was most precise. It can look a bit messy, nobody will see it. 
7. Ensuring your pad is straight, refit the upholstery using the clips as guidance. Ensure the main wire is down through that hole in the sponge. Peel the double sides tape prior to the refitting of the upholstery. 
8. Referring back to the Toyota guide, over at the seat assembly / rear back rest, move the fabric parts that enable you to pull up the upholstery. This pad can sit much lower, trim your pad along the top so you have about 1-2cm of non element as border. Align the top of this with the ridge on the foam - this is as far as you'll have been able to pull the upholstery up to, and don't need to pull any further. Hold the pad in place, with the double sided tape peeled and allow the bottom of the pad to wrap around the bottom of the backrest. 
9. Begin reassembling the seat according to the Toyota guidance. 
10. CAR ELECTRICS
11. Strip apart your interior. Starting with the driver side / doors bottom edge plastic trim - the long piece. Pull it up, it pops off. Then the adjacent part, more forward / corner piece of plastic trim. It has one bolt (though mines was missing) then it pulls off.  Next, two screws under the drivers footwell to remove that piece. It's the bit right above the pedals. Next, the two gun metal grey trim pieces on the centre console (both sides). Pull off the soft touch 'V' shape surround around your cupholder trim. Pull off the front two trim pieces (both sides), the front most side of the centre console. Then the part behind it (both sides).  Inside your centre console box, lift the inserts out. Unbolt the three bolts (10mm if I remember right). Pull off the trim piece behind the centre console (its back facing the back seat). Screw off the gear knob until it comes off. Gently pull the phone holder trim up / cupholder gun metal grey trim / gear gator piece gently. There are two finger plastic clips on the phone holder trim to remove. The trim should now come off. 
12. Drill your holes on the trim piece similar to mine. I can't remember the drill bit size (sorry) but it's the size of the back of the switches. Use a file to round this off / trim as needed to get the switches to fit without being jammed down. If they're clicky and upright, you've done it right. 
13. Whilst everything is pulled out, solder in your cables: blue to cigarette lighter live, black under the carpet to the driver footwell ground / earth point, red to the blue cable you'll see in the loom cable tied to the cars body near the earth point on the body / footwell side.  
14. Position the heated seat control box under the metal brace which lives inside the centre console / behind the gear stick mechanism area. Tuck in the spare length of the pad wires under the other metal brace which supports the centre console storage area. 
15. Ensure the cables have length / reach where they're meant to:  red / black under the carpet and out along the side to the earth point / loom.  Each pad connection: out the sides that will come out from under the centre console. Ensure the little wires for each switch aren't held under anything and will be able to go up to reach the switches in their position on the gear gator / cupholder trim piece. 
16. Re assemble the inside / trim. 
17. Refit your seats connecting everything up. 
18. Give it a spin! 

For all the work, this is all you'll notice different. That, and the beautiful, beautiful feeling of fast head on demand. 

class job shane my friend looks great tbh i was going to do that myself but i just didn't fancy the work thats involved into it thats why i went the lidal route 

[Guest]

3 hours ago, 2009joe said:

class job shane my friend looks great tbh i was going to do that myself but i just didn't fancy the work thats involved into it thats why i went the lidal route 

it was !Removed! difficult.  I did it in 2021, vowed never again. Ordered the kit last summer. Got the seat out. Took a good look at it. Thought nah, and returned it.  Took another year to mentally prepare for it... 

Well worth it though. Went for a drive today to Starbucks. Nice warmth. I mean, intolerably hot. Only OEM one I felt that hot before was a Range Rover Evoque. Others all more than warm enough, but not that hot. This is up there with the Evoque in terms of heat. Setting 2, less burning but still quite hot. I can see that being handy in winter.  Setting 1, can keep it on the whole time, nice warmth but nothing too much.  

I love it. Toyota are odd. They keep everything: keyless entry, heated seats, headlight jet washer, memory seats, electric adjustment, 10 Speakers, push button start, all for the Excel!  

I will report back as and when any developments happen. If a pad breaks etc.  Anybody on here who has questions please ask I'll do my best to help.

[Avensis tourer]

RESPECT!!! It seems like a lot of work. I enjoy the heated seats in my Ford during subzero temperatures. It might take a year to think about and prepare mentally. I also miss having heated mirrors.

[Auris James]

Great job, but a lot of work. Would of thought pre-wired.

My Nan uses the heated seat in my 2015 Auris Hybrid. I hardy use them. May today in my 1996 Volvo 940 with full leather. Nice to warm up the cold grey leather! 

Was thinking of adding electric seats with memory in my Volvo 940  but gave up as most electric seats faulty/ motor problems or worn bolster. The drivers side is pre wired. Just fitted manual leather seats for £60 in good condition.

James.

[Guest]

Tomorrow is the shortest day of the year... pitch black when heading to work and back. Freezing stormy winds. 

Heated seats working a treat. 

Dare I say the Chinese specials are nearly too hot before setting them to lower settings... not complaining!   

10/10 would recommend. For 30 pounds and a day (maybe two).

[2009joe]

i have to say i like the heated seats also shane but i went for the less stress option of bought the lidl heated seats that you plug in .i have to admit there a great job in a cold nite