In an 84, 2 things feed the temp gauge. Both feed circuits can cause the
blinking and needle pegging.

One is the signal from the temp sender. This sender can fail but more
likely is a bare spot on the wire from the send rubbing against metal.
The wire can also fall off or get knocked off the sender and then touch
the engine metal. This will give a false reading of too hot, peg the
needle and flash the LED. The sender is in the thermostat housing. It is
the smaller of the 2 there, has only a single wire to it.

The other thing that triggers the flashing LED is the coolant level
warning circuit. On an 84 this will also peg the needle. During 85 this
was changed to not peg the needle, only to flash the LED. When the
coolant in the main tank is too low, or the sensor in the tank goes bad,
or the connector to the sensor gets dirty or loose, the sensor control
unit thinks the coolant is low and blinks the LED and pegs the needle.
Another weak possibility is the sensor control unit went bad and is
giving a false indication. The control unit is hidden and hard to get to
in 1.9 models but removing it is the fastest way to determine which
circuit is causing the problem. If the problem stops with the coolant
level control relay pulled, the problem must be with the coolant level
circuit.

The main tank is not the one you see from the license plate door, that
is the overflow tank. You must open the engine cover to check the main tank.

Mark

Gary Goldey wrote:

>My temp gauge needle is shooting all the way up on cold startup. Also the red
>dummy lite is blinking on and off. I have plenty of fluid, and symptons
>occoured on cold start-up---any ideas?
>
>Thanks----G.
>
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