Getting some miles on this thing, daily driven since Monday. Weather was really nice earlier in the week, this morning it was about 30 with frost on the windshield. Seems I got my moneys worth with the new heater core, heat and defrost work great.
Speaking of heat... My original seats were garbage, ripped leather, crusty rusty frames and busted adjustments. Kind of a good thing, since I didn't mind cannibalizing's them for the wiring harness. I cut off the seat connector, pulled some pins and wire splices from the other under seat connector, and proceeded to make a hybrid harness out of the Toyota plug and the Scheel-Mann harness. There is mixed info out there, so I grabbed the multimeter and test light. The Toyota vertical switch and circuit in the car provide a high "signal" on one wire and a low "signal" on another, just like the Scheel-Mann switch. I saw no reason not to connect all the Scheel-Mann input wiring (power, ground, high signal, low signal) directly to the Toyota under seat plug. since it has everything needed.
White plug is the Toyota seat plug, large black plug is the Scheel-Mann relay plug, small black plug is the seatbelt connector.. Wires headed under the seat are to the heating elements.
Unexpectedly, while the +12VDC under the drivers seat was ignition switched, I found the same wire was always hot on the passenger side. I didn't want to install this so the passenger side could be left on when the truck was off, so I planned to look for another ignition switched power source. Fortunately I didn't have to worry about it too long. When splicing the harness for the passenger side I realized that the Scheel-Mann +12V wire does not connect directly to the relay at all, it only provides power to the switch. Since we already have switched power from the Toyota switches / harness, we don't actually need +12V for the Scheel-Mann harness at all. I capped the wire and assembled the harness. This was actually exactly what I had done on the drivers side too, but I thought I was only capping the power and ground to the switch from the SM harness, assuming there was a wire directly to the relay. Did any of that make sense ? It's kinda late.
So, this is not a tutorial, I am not a professional automotive wiring expert, I'm an idiot. Don't burn your truck down doing what I did, but for me and my truck and the SM harnesses I received, I connected the truck ground to the SM ground, and the switched circuits from the truck to the SM switch inputs only, that's it. And I have working heated seats using Toyota switches with working indictor lights. Simple and easy.
Only current modern vehicles I have to compare these heaters to are my Mazda 3 and our GX 460, both '18's. The Mazda seats take a while to warm up, and get comfortable but will never get uncomfortably hot (of course they will be too warm once the car is hot, but they never feel like they are going to burn you), the Lexus seats heat up fast and will roast us out of the seats on high. The Scheel-Mann seats are between the two, they take a minute to warm up, but will melt things in your pockets once they get hot. Both my wife and daughter think they get as warm as the Lexus seats, just take longer to get there. Testing them this morning they took about 5 minutes to really warm up, but in 10 we were switching them to low or off.
Jason
