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Supporting SSR Hobbyist
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Hi Mike.
I am sure that the black box controls the cooling fan and takes the data from the generator, the mass air flow sensor and the temperature sensor as signals.

The mass air flow sensor, I think, is needed to turn off the fan at speeds above 35 miles per hour.

The generator says the engine is running, and not just the ignition on.

But this is not like local masters)

I think that the system was on full-time management and then a regulator from tayota was added to it.

Today I tried to figure out the logic of work, relay number two works and is being tested correctly by the diagnostic complex, but relay one, according to the diagnostic data, has a short circuit, I checked it with a tester and really, it always has + and -

I could not find the wires on the Powertrain connector.
Where can I see Pinout for Powertrain?

The black box you have connected to your SSR is NOT a Chevrolet part. There is no documentation on that box. Additionally:
1) The power connection on the alternator is connected to the battery at all times and cannot be used as a source of data.
2) The mass airflow sensor has never been used as a speed sensor. It measures airflow into the engine, dependent on engine demand.
3) The temperature sensor on the engine is connected to the engine PCM, not any external box.

Here’s how the system works:
Coolant temperature is measured at the sensor near #1 spark plug. That measurement is done by the PCM and data is sent to the instrument cluster. The data is also sent into the cooling fan control logic in the PCM. The logic turns on the low speed relay at 226F and turns it back off at 219. The logic will also turn on the high speed relay at 235 and turns it back off at 226. Both circuits pass through a logic “gate” that is turned off at 35mph. The signal that turns off the logic gate comes from digital data that originates in the anti-lock brake system. The actual source of the signal is the speed sensor in the transmission. That same digital speed data is also used by the instrument cluster to move the speedometer. Sensing for “engine running” also is controlled by the PCM.

The two relays for the cooling fan operation have the following connections:
The 60 amp power source (fuse 44) is directly connected to the power contact on each relay. The other side of that power contact goes directly to the cooling fan. One relay to the low speed wire, the other to the high speed wire.
The solenoid power is connected to the relay and powered by a 10 amp fuse (fuse 9) in “Run/Start”. The solenoid ground for each relay is controlled by the PCM.

I would recommend you make a sketch of the additional “non-standard” wiring in your truck. It will be useful when you start to restore the OEM wiring configuration.

I am sending your package today.

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