So I decided to take my mk3 for an MOT and it has been sat for a couple month's. When I drove it to work the gauge was fluctuating from normal to red and back again. Got to work, the car was not overheating and coolant was not pressurized. I disconnected the sensor and the gauge dropped a bit but was still fluctuating up and down. Had anyone come across this and could it be a faulty instrument cluster or more likely an earth ? Also it cut out twice and realised the crankshaft sensor wire was brittle and shorting so I ordered a new one. Any advice on what to test would be appreciated. Thanks in advance.
if it still did then same with the coolant sensor unplugged then yes this would point to a wiring or possibly cluster fault. Have a look around the engine block for a brown/white ring terminal, the clocks may have an extra earth here. While you're under the bonnet carefully follow the 2 sensor wires for the dash back to the round plug, and from there back as best you can towards the fusebox looking for any damage. For the MK3 4 pin sensor, pins 2 and 4 are for the dash temp sensor.
Thanks John. I think it's the speedo head as the fuel gauge is moving slightly as well. I have another mk3 so will swap it over and see if it cures it. Thand for your help again.????
might be the voltage reg inside thats gone, not sure if you can fix them on the mk3? have a look at the earths to the head just in case, hopefully its that nice cheap fix
