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Thread: Seat heater, thermometer, scangage II

  1. #1
    Van Fan
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    Seat heater, thermometer, scangage II

    Dorman seat heater, gets really hot, good place for scangage II, thermometer. Toughest part is partially removing the seat cover to get the seat and back pads in. Electrical hookup not hard with add a fuse. Low setting gets hot enough. Looks pretty oem to me!
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  2. #2
    Van Enthusiast
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    Re: Seat heater, thermometer, scangage II

    Here's what I did for heated seats on my 1992 Previa (OBD1, so no scangauge option)
    Agree that "High" setting is only for initial warm up for a couple of minutes on a really cold day.
    (Previously posted to the Yahoo Previa Group)


    Toyota Previa (1992) Cloth Upholstery – removing, replacing, adding heating.


    What you’ll need:


    • Gloves – lots of sharp sheet-metal edges to deal with
    • Old towel(s) or something to put seats on – lots of filth, depending on how many kids and dogs have lived in that van
    • 14mm socket wrench to remove seats, and preferably a torque wrench to properly replace them at 29 ft-lb.
    • 12mm socket for inner bolts
    • “Hog rings” for automobile upholstery – basically staples on steroids – you can get them at NAPA or online. #5 size. Box of 500 for $8. Maybe I used 40 – on 2 cars…
    • Hog ring pliers – bought at NAPA, angled KD Tools 3704. There are straight ones, there are kits. Just don’t buy something really cheap. You’ll only need one, straight or angled.
    • Something to cut existing hog rings – I picked up a pair of AmPro “Easy Grip-Cut” “High-Leverage Pliers” at the local Ace Hardware. Seemed really well-built for the price, but anything that’ll cut through 2mm-thick wire with just a reasonable amount of force is going to do it.
    • Seat heating kit – I went with Rostra 250-1870 Universal Kits (1 per seat) from Summit Racing – about $60/seat. Putting them in the seats was not too bad, wiring them to the power and switches in the Previa was kind of a P.I.T.A.


    Seat disassembly:

    All the lower seat cushions consist of a metal pan fastened to the frame with 4 12mm bolts.
    A foam cushion sits on the pan, and the seat cover is placed around it and fastened to the lower edge of the pan using long plastic pieces. Sewn around the lower edge of each cover, they’re pushed up and over the edge of the metal pan (so its edge is within the “trough” of the fastener), then pushed down to snap into place. They're sort of a macho version of those thin plastic binding strips that clasp the side of multi-page documents.

    Once you've dislodged the front of the seat covers, the seat heater pads can be slipped in between the cushion and seat covers with no modifications, since there are no attachments between the covers and seats where the pads go. That's fortunate, since I did the same thing with a Camry, and it had at least two places where openings had to be cut in the heater pads, meaning the seat cover had to be removed to install them.

    In my case I took the covers off completely in order to get them resewn, some foam repaired, and 20 years of accumulated filth removed. Be warned: this involves patience and gloves for both protection and probably infection control if your van has been as "lived in" as mine.

    The seat cover is also fastened down to the foam itself on the seating area using wire “listings.” Each consists of two stiff, straight wires – one sewn into the cover and the other embedded in the cushion – which are held together using hog rings, which are crimped over both at intervals using hog ring pliers. There are also rubber cords that run from rings at the top of the seat backs down the vertical "channels in the cushion, and then hog-ringed to bars at the bottom of the seat. Take lots of photos to remember how to put them back - take special note of the sections with molded-in flanges that are positioned on either side of the bars they're attached - obviously to prevent them from slipping out of place.

    Tip: the headrests can be removed off after pushing in against the outside top sides of the seats - put your thumb on the outside, fingers on the inside of the bolster and squeeze. Underneath the fabric you have the same release button as on the rear seat headrests, only it catches on a single slot in the headrest mounting post.

    I didn't have any rips in the fabric, but had lots of places where the seams were coming apart. I took them to an auto upholstery place where they were resewn, then gave them multiple, washes in Whisk, which they recommended. In the end, I saw colors I hadn't seen in 10 years. I also had the chunk of disintegrated foam replaced in the driver's seat cushion (the left bolster section on the seat belt side). The charge for foam repair and resewn seats and backs for the both front seats ran $80 in Jan 2013. No doubt you save a lot of money by not bringing in the entire seat because of all the labor involved.

    Wiring

    I wanted as clean an install as possible (Hey, I'm on the inside - I don't see the still-in-black-primer fender, peeling clearcoat and rear wheel-well rust holes), so powered the seats from a tap into the IGN line below the fuse panel through the two fuse holders hot-glued into an empty spot on the panel (where I removed some unused plastic protrusions for them to fit). Their positive red wires ran across to the left and down to the right of the accelerator pedal next to the harness for the crash-detecting airbag-triggering electronics hidden below the open storage tray. It was joined by a ground wire attached to one of the two ground points behind the upper dash (neither of which is what you'd call easily accessable). The heater relays were placed under the tray adjacent to that crash detector, and the two HI-OFF-LO buttons were mounted to the rear of the tray (the only place I could figure out where to put them). From there, wires ran under the carpet to the rear of the two front seats, which involved adding a few inches for them to reach. I also placed aluminum heat-resistant duct tape under the wiring where it ran over the engine.

    previaseatoverview.jpg
    Previa fuse panel underside.jpg
    Ignition tap.jpg
    Seat Power IGN Splice.jpg
    IGN run to fuses.jpg
    Seat fuses.jpg
    Ground point access - left dash support.jpg
    Seat Heater Switches.jpg
    Seat Heater Wire Run.jpg
    Previa_SeatHeaterWire-DriversSeat.jpg
    Seat heater run to passenger seat.jpg
    Last edited by man_btc; 10-02-2019 at 07:50 PM.

  3. #3
    Van Fan
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    Re: Seat heater, thermometer, scangage II

    I stuck my ScangaugeII in the pocket under the radio.

    Ah the scangauge... so innovative back in the day but totally blown away by modern tech.

    My '95 works with some OBD2 scanners but not others. I'm guessing it depends on if they read the ID and have an invalid value error when they see it's a '95.
    -Russell
    "You don't get to judge me for how I fix what you break"
    -95 Previa SC RWD
    -05 Subaru Baja Turbo, 03 Subaru Baja NA, 01 BMW R1200c, 94 Firebird v8, 70 VW Beetle

  4. #4
    Van Enthusiast
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    Re: Seat heater, thermometer, scangage II

    I know folks periodically get flummoxed trying to get the head rests off the captain's chairs, and I just ran across a pic I took of a "skeletonized" chair so thought I'd add it here to show exactly what's under the upholstery holding the headrest bar (which has a notch in it) from coming out. This is depressed through the top outboard side of the seat by squeezing through the cushioning
    Attached Images Attached Images
    "If you find yourself holding a sledgehammer or a crowbar, it's time for a break."

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