Temperature sensor controls the length of time the glow light stays lit, it doesn't effect the timer in the relay which is set permanently to a fixed number of seconds.

Yes, you could turn the whole glow system on/off by switching the main line to the glow relay. However, it carries a lot of current so you'll probably need to use a relay under the hood, triggered with a switch on the dash.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13