Flashing light on water temp dial

Is the flashing red light the level or temperature warning?

Cheers, Skipp

Depending on year of car I think it's both, I don't think all cars had the water level sensor in the expansion tank.

However, they regularly go wrong, mine has been constantly flashing about 50% of the time for the last 30yrs.  It's got better recently after replacing the coolant level sensor, and water temperature wiring connectors, but still dies it every now and then, rather than go out after a few seconds of the engine starting.

Mine is an 83' but I have just put a 20v in. It has a topfill alloy rad in. When I start it up the light is off until I Rev the engine. Then it won't stop flashing. Fan kicks in when temp gets up so I can only presume it's the level. Can I join any wires or anything to stop it flashing?

look above the fusebox for a relay 42 or 43, if fitted remove it and the level warning is disabled.

the light you see may be overheat warning, triggered by an incorrect coolant temp sensor. the mk4 one wont work the mk1/2/3 dash so you need to fiddle:
http://www.clubgti.com/showthread.php?267196

Spot on. I shall source a Mk3 sensor. And just a case of matching up the 4 wires?
Cheers

the pinout differs on the early/mk3 square sensor to the late so use the info in my guide to get it wired properly

the mk3 sensor wire colours are usually different so its a case of cut the mk4 plug off, use the list of mk4 wire colours to id which is which then use the pin number list to work out where they go on the mk3 sensor

If you find an early mk4 to rob the square plug from the pinout is the same as MK3 and the wire colours will probably match up to what you have, but it depends on the engine code. Usually 3 are the same, its just the ecu temp sensor wire that differs.

double check everything with my guide regardless though

I have got a Mk3 GTI sensor but have the loom/plug from an early non GTI Mk3. The wires in this plug are:
1. Brown
2. Brown/yellow
3. Red/black
4. Yellow/red

Can this still be used?

as long as it plugs in then you're good, just wire it up as per my guide

So I have put the wires as follows:
Purple - pin 4
Brown/white - pin 2
Grey/yellow - pin 3
Brown/blue - pin 1

But now the red light flashes even faster. Do I have the wrong sensor?

thats fine, any part numbers on the sensor?

it could just be knackered. ideally get a new genuine one, keep em peeled can often find cheap on ebay