Whirlpool AMW 590 IX Oven Error F04: Diagnostic and Repair Efforts, Contactor Voltage Query

The message appeared sporadically, turning off the network and turning it back on again. Until one time it did not restore and remained. On English-language pages I found ... Communication error between the operating module (the one with the knobs and the display) and the oven power unit.

An experienced serviceman withdrew (escaped) that there was no part in his company. Replacing the service module with a new one (expensive!) Did nothing, the error is still there. On the power unit board everything looks good, measurements without sensation, voltages 5.01V, 16.85V, and 9V, voltages refer to the power supply. Is it OK that the contactors are powered by 16.8V, and they are 12V?

Prophylactically, I replaced the Vss diode, Zener diode at the Tx / Rx output and the electrolyte in the power supply - to no avail. I can't check prock or integrated circuits. All surrounding elements in working order.

Advice on what to decide:
- give it a rest and throw the oven away agreeing to the loss of a few hundred per module + purchase of a new one
- take a risk and buy a power module (the one with contactors) or oven power unit - again a few stacks (do you need programming then?)
- look for the source of the error on this CD, but how to do it?

I am a retired engineer + as a hobby for 40 years of various electronics. Maybe someone has a schematic or service manual? However, I don't even dream ...
Oven No. service: 858759010792, and this power module: 461968804972
Regards
JWG
I have corrected TONI_2003

F4 - Shorted Oven Temperature Sensor (RTD) - Replace oven temperature sensor (RTD).

Unfortunately no, the temperature sensor checked, even the removed characteristics up to 200 ° C for fun, say. Resistance from 1080?. Indeed, such a hint is given on several pages, but maybe it applies to other models or what, and on others, however, there is a communication error between units. Thank you.
JWG

Finally, I started this oven and to help successors with a similar problem I inform you how it happened:
- I bought a new power module for this oven - something about PLN 500, as assured by the seller, it is already programmed (important!)
- assembly of the module is a trifle, by the way one wire on the multi-pin plug to the operating module (the one with knobs) broke, repair
- after switching on the voltage error message F03 popped out ... What does the problem with the eeprom memory mean, how was I explaining the module was not programmed?
- telephone to Whirpool Poznań with a request for programming service - refusal. I heard the old type of oven is strange because it is still on sale. They do not like those who tinker with household appliances.

I read on the forum of invaluable Electrodes how others delete the error message on other equipment and did so:

- disconnect the oven from the power supply + wait + press the two buttons i.e. OK and the other one and hold both + switch on again. warning !
- the left knob with programs must be vertical, i.e. the dot at the top. SERVISMODE will appear.
- turn the knob to the left, from the programs to the right, one jump - the lamp will light, the second third, etc., and the program number that will simultaneously start in the oven will be displayed in the bottom right corner of the screen!
So the oven works though in service mode.
- turn the knob further up, i.e. to the position as at the beginning, and press the OK button. And then success!

A screen will appear - time setting - which is normal at startup. The oven continued to work normally. So it was done without a bad service and the equipment was saved.
Regards