VW Vanagon Temp Meter

Dec 07, 2004 2 Replies
M

I've got something of a gremlin working in my 1984 VW Vanagon-Westfalia (2.1L water-cooled) in which the temp guage, located in the instrument panel will often drop down to a zero reading, flash the red LED and then return to normal temp after about 10 seconds.



I assume it's some kind of short, but it also could be related to power drain (it will do this when I first flip on the headlights) and sometimes while driving in heavy rain and I hit a large pool of water at highway speeds (rapid cooling of the sensor?).



Anyone have any insight into how this red-LED is triggered and/or the zero-reading of temp?



Thanks in advance.


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I

No. The sensor is located in a coolant hose flange, no rapid cooling there.

The LED serves two purposes:

- blink when the temperature is too high, it is triggered right before the needle of the gauge reaches the right margin of the scale.

- blin when coolant level is too low, this is triggered by a sender in the coolant reservoir, and a special relay in the fuse box. There is a lamp test too, and this is most likely what you see: Whenever the voltage returns to the circuit the lamp will blink for a short time - and if the power is lost intermittendly you will only see the blinking if it returns right away, and you will see the needle drop to zero if the power loss is longer. Two possibilities for this: +12V from ignition is lost or gnd is lost. As you see interference with the other circuits (lights) it's most likely a ground problem. Check ground connections, start with the big one in the engine compartment (battery, engine/tranny), then check the ground connections under the dash - all brown wires, going to a terminal block with spade connectors.

Ingo

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F

Most likely caused by a leak in the cooling system, when air in the hose reaches the sensor. Check the rear heater core for leaks. Could also be caused by an improper coolant refill, if the front-end wasn't elevated while the air was bled off.

Fran

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