MG Car Repair: cooling fans & dash lights, inline fuse, header tank

Question
My cooling fans have stopped along with my dash & running lights,
is this a easy fix or a major problem?

MGB 1977 4 cylinder!

thanks much pete

Answer
Hi Pete.  There are 2 separate problems here.  Unfortunately, they are not so simple.  The running lights are on two separate fuses, so it is probably a switch fault.  On a 77B that is inside the steering cowl.  They fail regularly.  You probably need a new switch.  

The cooling fan is singular on a 77B, unless you have a USA car.  Your problem could be the fan, or the switch, or the wiring, or the inline fuse near the fusebox.  Try shorting the two wires to the switch in the radiator header tank.  If the fan works, it's the thermostatic switch that has failed.  If not, get back to me.

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If you have a USA car with twin fans, please note that they are both wired via the thermostatic switch in the header tank.  This overloads the switch and they regularly fail.  I would rewire the fans so that they are operated via a relay.