I had the exact same experience with one of mine (I have three). SG was great to repair/replace. Turns out it was a faulty harness.
Great product, particularly the coolant temp for the 80 and the trans temp for towing with my Taco. T
KA7TLT - TLCA 13015
"78" FJ-40 - "Marmot" F&R ARB Lockers, OME Suspension, MAF Shackle Rev Kit, 4+ Flip Kit, Rear Disc Brakes, Warn Winch, Safari Snorkel, 4+ Rear bumper/Tire Carrier
"95" FZJ-80 - "White Top" F&R ARB Lockers, Slee F&R Bumper & Sliders, Warn Winch, 35s, Safari Snorkel, Low Range Gears, P/T Kit
"13" Taco 4X4 Extra Cab, Firestone Air Ride, Airstream tow vehicle - "Daily Driver"