Fiat Palio 97 TD heater light

Hello people I need your help, I have a G1 TD 1.7 97, my problems is that I do not turn on the light of the heater and therefore the car does not start, I put a new timing box and nothing, I changed a relay that is behind the battery and nothing, probate with another start drum and nothing, the only way to start it is to put a cable in one of the chips of the aforementioned. Positive of the battery, I already have no