Only the 83 and later diesels have the coolant level circuit. The "43"
relay is well hidden in all 83-85 models, up under the dash, on the left
side, above the level of the fuse box. The easiest way to SEE it is to
pull the defroster vent from the top of the dash, to the left of the
steering wheel. The "43" relay is in plain sight then. If your hands are
small enough you can reach in through the new hole in the dash and pull
the relay. I have to drop the fuse box and reach up from down there
while looking down through the new hole.

If your flashing still occurred with the relay out, the problem is not
the relay or any other part of the level circuit. It is quite common for
the temp gauge itself to be the cause. There are some electronic
components that control the flashing, inside the gauge that fail,
causing intermittent or even constant flashing. One way to know that
this is what it is causing it is to note carefully how the flashing starts.

Normally, when you turn on the key the flashing starts as a self test,
then after the engine starts it goes out. If it begins again after at
least several seconds later, the level circuit is likely at fault. If it
never goes out when you start but continues from when the key was turned
on, the fault is most likely in the gauge itself. Years ago here we
covered all this in much greater detail and some listees actually took
their temp gauges apart and replaced the failing capacitors. I'm afraid
those days are behind us and the current owner base can't seem to follow
2 or 3 simple steps, much less the dozens needed for such a repair.

Mark

Jim Felder wrote:

> This weekend I pulled the #42 relay and my coolant light still blinked,
> making me think it was indeed the relay at fault. After removing and
> replacing, it worked perfectly--once. Then it blinked for maybe 10
> seconds, Then a minutes. So, all this points further to the relay.
>
> I realized today that there is one in my diesel, but I don't know where
> it it. It's in the dash somewhere, but what's the easiest way to get to
> it?
>
> Jim
>