still havnt sorted the rad fan not coming on changed the resistor but no change fan will work if I disconnect the lead on top of the thermostat, will look at the fuses and relays next.
You've already proved they're OK when you disconnected the temperature sensor on the thermostat.
Three possibilities :
1. The temperature sensor has failed
2. Everything's fine, you just haven't allowed it to get hot enough
3. Problem with the engine ECU ( somewhat unlikely ).
If you have a multimeter :
With the engine cold and off, again disconnect the temp sensor at the thermostat. There should be three wires to it and three pins in the connector. Identify pins B1 & B2 ( they correspond to the Green and yellow wires ) and measure the resistance across the pins. At 20°C it should be about 2.5KΩ so with current ambient temperatures it'll be slightly higher. Also measure the A1 pin ( corresponds to the White or Grey wire ) to earth. The two measurements ( B1/B2 and A1/Earth ) should be similar ).
When the car is next up to normal temperature repeat both measurements. Again, they should be similar but this time they'll probably be ~ 300Ω.
If the measurement of the B1/B2 terminals is significantly different to the A1/Earth measurement, you may have a fault with the sensor.
If the B1/B2 measurement is higher than than the A1/Earth measurement then the temperature gauge is indicating a temperature higher than the engine ECU is seeing.
If you have DnDiag or MultiECUScan and a suitable lead, you can :
- Use the software to see what engine temperature the ECU is seeing in °C
- Use the software to instruct the ECU to switch on the fan(s) at both speeds
EDIT : corrected resistance figures. No idea what I was thinking. Apologies.