Rev counter causes cooling fan to stay on !!!!!!!

[Mr unknown]

Right then HELP...fitted a Ebay(might have ans the question)Dash mounted Rev counter the other day to My 51 plate 1l and I have now found that the electric cooling fan is permantly on.3 wires on tacho...red positive black earth and green to dizzy.Connected the black to earth.......red to the yellow cable in the plug at the dash and the green to the blue/black as per haynes workshop manual. Am I missing something here....also I have found that the tickover on idle has increased to around 1100rpm when it should in fact be around 750....also the voltmere is now showing 13.8v instead of its normal 14.1...Yes I know it is not a lot of difference and it is hte fan that is puttng the volts down

ANY SUGGESTIONS...I simply have not had the time yet to dissconect the rev counter to see what happens

In all my years of Wireing rally cars etc I have never come across this one

Dave

 

[SuperUno]

The ECU temp sensor is damaged, disconnected or not working.

 

[Agent_Sm1th]

You haven't got a dizzy? Anyway aside from that, the ground needs to be a good one. The live needs to be switched (preferably not from the instrument cluster) and the signal needs to go to the blue/black wire. You must be back feeding into the ecu which in turn is running the fan(as it's relay gnd activated) which in turn will increase the idle to 1100rpm.

Sent from my WAS-LX1A using Tapatalk