Lada Niva 1.7i 4x4 21214 - The radiator fan does not work: error P0480

Hello,
Car: Lada Niva 2003
BOSCH MP.7.0 injection system and EURO - 3 standard

I have a problem with the radiator fan.
After the engine is heated to the temperature that starts the fan 95-100 C, error code P0480 appears (continuity of the electric circuit controlling the fan relay 1 - break, short to ground, constant voltage + 12 V).
After turning the station on the ECU pin "46" it is + 4.21 V, after starting the engine it is + 4.24V - + 4.25V, there is no change in the value during the temperature increase.
After exceeding the specified engine temperature, this pin should give mass to the relay that activates the fan, but it does not happen.

After disconnecting the coolant sensor with the engine running, the computer should go into emergency mode and start the fan, but this is not the case, this sensor is also responsible for the position of the throttle stepper motor, what to listen to when disconnecting.
The coolant sensor is + 4.89V and ground.
The fan is in good working order, it works for a short time and it works when the ignition is turned on and I give ground to the relay pin "86" to which the cable from the ECU comes from the pin "46", and the fan starts.

Thank you in advance for the hint.

https://www.drive2.ru/c/677196/

Google translate))

bsv2001 wrote:

https://www.drive2.ru/c/677196/

Google translate))

Before getting on the electrode, I browsed through all the Russian pages, including this one. I have been using Chrome and Chromum since I was a child .

This solution does not suit my situation too much because the voltage on pin "46" is within the correct range (it cannot be higher than + 5V and less than + 1V).


All fuses are operational. Relays as well, I checked the resistance of the relays, I checked the switching of the relays and the current efficiency.

The only problem I noticed myself was the lack of mass when the temperature was reached on pin "46" of the computer. I wonder why and if, maybe this is due to the lack of information about the engine temperature that should reach the computer. Besides, there are no other faults and disconnecting the coolant sensor does not start the fan.

I forgot to mention that when the relay is disconnected and the car starts, error P0480 also appears. This indicates an open circuit.

The interruption is also not the cause of the fault.

There is only a short to ground or constant voltage + 12V,

A short to ground would activate the relay so the fan would spin continuously.

I don't know what the + 12V constant voltage can mean and what could be the reason for it.

karol9977 wrote:

This solution does not suit my situation too much because the voltage on pin "46" is within the correct range (it cannot be higher than + 5V and less than + 1V).

Only as relay removed. If everything is in place, the voltage should be the same as on the battery.

ociz wrote:

karol9977 wrote:

This solution does not suit my situation too much because the voltage on pin "46" is within the correct range (it cannot be higher than + 5V and less than + 1V).

Only as relay removed. If everything is in place, the voltage should be the same as on the battery.

Yes, when the relay is removed it is 4.21 V after inserting the relay it is 12.3 ... V

Hello Dear, I was checking the coolant sensor today, using a heat gun with an electronic thermostat. After the sensor is heated to 100 "C, there is a flow between the two pins of the sensor. I decided to short the 2-pin cube that goes to the sensor of the above-mentioned sensor. To my surprise, the fan did not start again. I analyzed the errors and the unwelcome error P0480 appeared again. and the P0117 sensor error which indicates the sensor is damaged (but in this case it is no wonder because the sensor was disconnected and the cube was bridged).

From my observation, it appears that the computer receives information about obtaining the temperature at which the fan should turn on, but the ground is not derived from pin 46. Why?

Is it maybe the fault of the integrated circuit responsible for switching the + 5V current to ground or what is it about?

is this scheme good for something?
https://docviewer.yandex.com/?url=ya-disk-pub...%2F%2FM73_ES_IA_%R573.pdf=58name=2R573.pdf=58

The thought occurred to me to solve this problem in the easiest way. If I connect the pin from the sensor to the pin to relay 46, the fan will turn on. What does the electronics think about it?

but on the other hand, it probably does not work like that, I don't know if I accidentally overheated the sensor to get the transition, besides it has other functions, e.g. it starts the stepper motor ...

I checked where the signal should come from to the mass of the relay. How to check why there is no mass on pin 46 and is it the fault of this integrated circuit?

From this chip, the mass is sent to CHECK ENGINE, the fuel pump relay and the fan relay, There is +4.24 V on the foot of the pump relay, the same is on the foot of the fan relay,

While the scaler foot, responsible for the mass of the pump, turns into mass, the fan foot does not ...