Got a used GP relay to replace an intermittent old one. Good news is the light pops right on (the old relay I sometimes had to smack with my hand to get it to reset). Bad news is it's little quick to extinguish the GP light. In other words, it's like 40 degrees here, and it pops the GP light on then off pretty damn quick, like instantly. The relay senses coolant temp right? Might the sensor be off? Remedy? It's a relay from florida. Maybe it's just acting weird like any Floridian that steps off the plane in Boston in March? I will try again today hoping for a longer GP burn and await your response. Thanks.

Oops. I said 617. But it's a 85 300Dt (CA car).

I've heard the light is driven via a transistor in the relay....it could be damaged or flakey...key thing it how does the car start...that light doesn't have to come on for it to function.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
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There is a post about the light not coming on at all, but the relay still functioning - it's not that old of a thread.
Like BHD said, the light doesn't have to function for the relay to work. Listen for the relay to clink off. (this can take up to 90 seconds)

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It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

The relay measures ambient temperature to control the time the light operates. There is an electrolytic capacitor in the relay that affects what this time is. If that capacitor is leaky, your light time will drop. The relay should keep running for 30-90 seconds, although the current draw decays exponentially.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Car coughs on startup. Never did before. But it does start. I guess I need to pull the multimeter out and see if it's staying on. I just got the GP relay, so I dunno, I may have to give it back. It's not a dash light issue. there's definitely somethin going on.