The engine start system of a KamAZ vehicle can be in three alternative states: serviceable, operable and faulty (failure)

If the starting system is in good condition, the engine starts, and the condition of all devices meets the requirements of the technical specifications.

When the system is in working condition, the system provides a confident start of the engine, but the technical condition of some devices does not meet the specifications.

In case of a malfunction (failure), the engine cannot be started due to a malfunction of one or more devices of the system.

We will not consider the correct state of the system, since we are not faced with the task of determining the period of failure-free operation of the system by the number of starts or by the mileage of the car.

To perform most tasks, it is enough to have the system in working condition, when the system provides a confident start of the engine.

Therefore, first of all, we will consider the failure of the system and possible malfunctions, we will indicate ways to quickly identify and eliminate them.

The system consists of seven devices, each of which affects the operation of the entire system.

Therefore, in order to optimize the troubleshooting process, it is necessary to time each test and evaluate its impact on the performance of the starting system:

Tightening the KamAZ battery tips

Checking batteries

Remove the cover from the battery compartment. By external inspection, check the condition of the terminals of the tips and the tightness of their fastening on the pole terminals (Fig. 1).

The density of the electrolyte should determine the degree of discharge of the battery. Checking time - about 5 minutes;

Checking the presence of voltage on the ammeter

Remove the instrument panel mounting bolts and tilt the instrument panel towards you or place it on the steering column.

In this case, free access to the terminals of the ammeter opens.

Connect a test light in series to the input and output of the ammeter.

If the light on the “+” of the ammeter is on, then the circuit to the ammeter is working, and vice versa.

Then check the "-" of the ammeter. If the control lamp is on, it means that current passes through the ammeter, and faults should be looked for further along the circuit.

If the lamp does not light up, then there is a malfunction in the ammeter. This check without replacing the ammeter takes up to 2 minutes;

Check instrument switch and starter

Checking the instrument switch and starter KAMAZ

Before checking this device, it is necessary to carry out preparatory work to provide access to the conclusions.

To do this, remove the shield for the electric motors of the cabin heating system, unscrew the nut that secures the instrument switch and starter, and remove the device from the panel, leaving it on the wires (Fig. 2).

Remove the red wire from the “AM” terminal and check the presence of voltage with a test lamp.

If the lamp is on, then the circuit to the instrument switch and starter is working.

Then you need to connect the red wire to the “AM” terminal, turn the key in the instrument and starter switch to the second position and check the “CT” terminal (green wire) with a light bulb.

If the lamp is on, then the instrument and starter switch is working.

Starter interlock relay

This relay is installed under the hinged fuse panel.

The relay is assembled on semiconductor devices and it is impossible to check it with a test lamp.

A special device is used for verification.

A malfunction of the starter inhibit relay does not necessarily lead to a loss of operability of the starting system, so this check should not always be carried out when troubleshooting;

Checking the starter enable relay

This relay is located under the fuse panel. Wire “+” from the ammeter to the output “K” of the relay. At the same time, you should hear the click of switching on the contacts.

In order to make sure that the contacts and the relay are closed, it is necessary to connect a test lamp to the “C” terminal of the starter enable relay (black wire). If the lamp is on, then the relay contacts are closing.

Checking the starter traction relay

Wire the “+” from the batteries to the terminal that retracts the starter relay windings.

If a click is heard, the relay is energized. The electric motor must rotate.

If the starter motor does not rotate, then a test lamp checks for voltage on the contact bolt associated with the motor.

If the lamp is on, then the starter traction relay is working properly.

Checking the electric motor at startra

This test is the most time-consuming, as it is carried out (usually) with the starter removed. It takes 30 minutes to remove the starter and 25 minutes to diagnose.

Since the electric start system has a small number of elements (only seven), the element-by-element verification method is used, or the sequential division of the system into two subsystems.