The two relays in the black box control the heater plugs and they work in two stages. At the lowest temperatures both pairs come on then only one pair.
It's worth doing a resistance check on the heater plugs as most have now mostly likely failed.
The brown relay has two relays inside and it controls the fuel pump and the the power to the ecu as well.
It's worth doing a resistance check on the heater plugs as most have now mostly likely failed.
The brown relay has two relays inside and it controls the fuel pump and the the power to the ecu as well.