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I prepared this to send to the FAQs part of this site but I guess the administrator's e-mail address has changed 'cause it came back undeliverable so I figure I'll post it here for anyone to find with a search.
Read through the postings on fixing heated seats in the SaabNet FAQs and notice that there's nothing about how to fix broken wires. As it happens this is very doable for anyone able to solder and willing to take the seats apart.
At least on my 89 900 they seem most vulnerable to breaks at two points on the bottom cushion, both sort of design failures by Saab because with a little more slack in the heater wires they could have avoided the stress that broke them.
The culprit is the horseshoe shaped wire that holds the seat covers down into the contoured bottom cushion. It is sucked down by s-shaped hooks that need to be unhooked from the support wires under the seat before the seat cushion cover can be removed. (This is after removing the seat from the car (unplugging electrics, two allen screws at front of driver seat and tip up at front and remove; two allen screws at front and two nuts removed from below at rear for passenger side) and after prying out the center of the seat back adjusting knobs, hooking up the prongs and twisting the knob off the spring clip that holds them on, and unbolting the backs at each side, then unplugging the heater wire that leads up to the backs.)
Besides unhooking I think it is 7 of the S-hooks from the wires (two of them on the straight wire that runs across the middle of the seat bottom), you need to pry off several steel clips on the leatherette seat skirt at front and rear and work out the ends of two fat wires at each side that poke into the metal seat base; then you can strip the leather or cloth cover off to really get at things.
By the way the horseshoe-shaped and straight wire run in canvas "housings" that are stitched to the leather or cloth at the main seams of the seat cushion but the housings are pretty flimsy cotton canvas and they chafe and rot through and may need repair or renewing to put the seat back together looking its best.
The seat heaters are a long run of zig-zagging Nichrome alloy stranded wire embedded in a foam base covered with a protective scrim of nylon gauze. The heater wire runs back and forth all across the roughly flat center of the seat, then (STRESS POINT 1) crosses over where the horseshoe wire sucks things down, and then runs back and forth along the rim of the seat and (STRESS POINT 2) back across the low point where the horseshoe wire pulls down, to run back to the connector that leads up to the seat back.
On my seat and I'd guess on most it's at those two crossing points where the wire had broken - - it also showed signs of burning. I actually think it grounded out there, to the horseshoe-shaped wire which had worn partly through its canvas housing and is grounded via the spring clips that hold it down to the wire frame of the seat through the seat base to the car body.
You can pull up the nylon gauze and pull the Nichrome wire out of the foam that it is embedded in to expose the breaks, and there's plenty of zig-zags there to yield you a little slack to make a repair without materially affecting the total resistance of the loop. I used a gas cigarette lighter flame on each end to pre-soften the insulation, which was work- and heat-hardened so that it was too brittle to strip. Once heated it stripped easily with a small pair of nippers. I scraped the exposed strands of Nichrome with a razor blade held sideways, to remove corrosion, slipped a little tube of heat-shrink on and slid it up a ways to keep it from getting hot prematurely, wrapped the scraped ends together, and they soldered very nicely with standard electrical solder. Then I pulled the shrink wrap over the joint and heated it. I pulled a little extra heating wire out of the foam to make sure there was enough slack that the horseshoe-shaped wire wouldn't put pressure on it again.
That was at what I called Stress Point 1. At "Stress Point 2" I figure Saab really screwed up as they needlessly brought the Nichrome across the gap and continued it about 2 inches before soldering it to the black return wire that runs to the connector to the seat back. I just lengthened that black wire a little and joined it to the Nichrome on the seat's rim, not crossing the gap for the horseshoe wire at all, soldering and heat-shrinking both joints as above (and as Saab itself originally did for the connections between the car wiring and the Nichrome wires).
If yours is only broken at one of those two stress points I strongly urge you to make slack at the other by pulling a few zig-zags of the Nichrome wire out of the foam.
After fixing the obvious breaks, check the bottom for continuity and eyeball it for any other breaks if you find a problem. As the FAQ on this points out the wires are usually black as if burnt just where there's a break.
Check backs for continuity; I doubt they need repair. But if they do you unzip cover at bottom and, as you turn it inside out to remove it, you come to a similar series of S-shaped hooks, to be unhooked from the back. Any breaks would be repaired on the same principle as above.
posted by 64.222.21...
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