Preheating S 10

Someone can help me. I have a S 10 2.8 TD, I had short preheater and jumped the fuse, repaired that, now I see that the signal of (-) does not reach the relay of the preal.
You can tell me if the timer is an independent module and where it goes, or if it is the ECU that manages time.
Any orientation and help will be well received.
Cordial hug everyone.

Theme resolved, as data I tell you that the fault was in the temperature sensor, the S10 activates the preheater only below the 10 °, change the bulb and the problem is over.
I hope this data is useful for someone,
a hug and the best wishes for all the forum friends.