Not sure on that one, since my rear heat is only on the floor. I will tell you though, that a few times last winter I popped my GFI outside outlet (later discovered a faulty cord), and went out on a -27*C morning last winter and it did start. I cycled the glow plugs twice and then it fired. It was lumpy for a bit, but at least we know they'll go, when unplugged, right? <img src="/forums/images/graemlins/kewl.gif" alt="" />

1991 HZJ77, 1999 KZJ90, 1999 UZJ100, 1992 M101CDN2
https://www.thegearheadproject.com/category/jdm-journeys/