EHR Bosch Hitch-Tronic 538201008 Controller: Relay Contact Behavior, MF 3000 Series & Schematics

Hello
I don't know if this driver is so "smart", because he hasn't been working with Fergusons for a long time, but Ford, NH EHRs are. If sensors and solenoid valves are not connected, it will not work. They remember, for example, what current should flow through the solenoid valves and in this way they know whether there is a break, a short-circuit or even whether the piston is stuck. They also know if the sensor is disconnected or damaged.

https://www.elektroda.pl/rtvforum/topic2083445.html

In the evening, I will post a diagram with the MF 3000 series, but they do not differ, maybe it will be more readable.

There is power from the ignition, probably on pin 1, and on pin 15, power supply when the engine is running, i.e. from the alternator. Connect the power to this pin and see if it holds the relay.

So that you at least deign to write in which tractor you have this EHR.

Second version with 24 pins.

I don't understand what this is for. The EHR module is powered from the console electronics or from the datatronic module (depending on the gearbox version).
The module needs a 10V reference voltage to power the draft sensors (tie pins) and voltage from the alternator (engine running).
I don't know why you want to connect the voltage from the battery. Originally, this voltage (via datatronic or console electronics) comes from the plug n (second from the top right of the diagram).
- 1 connector is +12V
- 2 connector is ground
- 3rd connector is lighting
- 4th connector is 12 V from the alternator (when the engine is running)
And on the 24-pin plug, respectively:
- 1 goes to 16 that is +12V
- 2 goes to 14 i.e. mass
- 3 goes to 15
- 4 goes to 17 i.e. the alternator

And will you finally kindly write whether it is datatronic or autotronic?
There is also 12V on pin 21, but in autotronic. If you have a datatronic and for some reason you powered the EHR directly from the battery (just write why) for 21, it could also work. I think that when it is powered from datatronics, there is voltage at output 21 anyway. Whether rugged electronics, I don't know. Probably no coincidence there are separate power supplies. Out of curiosity, what does the relay fire mean? It burns, it switches constantly, it explodes?
In general, you can apply voltage to any red/red wire with a stripe. Pins 21, 16, 17, 24 are red. We always supply power through a 21 W bulb connected in series (from the blinker). In case of a mistake, it limits the current.
If you write one sentence at a time, without explaining the problem, we will spend a month with you here. You will be reluctant to help. We are not unemployed.

And are you sure you have voltage on this 17 from the alternator?
There doesn't seem to be any relay hold-up voltage.
Have you opened the relay and contacts are good?

Wait a minute, and are you connecting according to the plug or according to the socket in the EHR? I gave you the pins on the C2 plug (see my post above). You have to go from there to C1.
Then:
power is on 1
alternator on 15
mass on 17