7.6.1. Maintenance

Check of the EPHH control unit

Fig. 293. Scheme of connections of a control system of the economizer of compulsory idling: 1 – control unit; 2 – the switchboard is transistor; 3 – valve electromagnetic carburetor; 4 – micro switch; 5 – EPHH valve; 6 – ignition coil; 7 – resistance additional systems of ignition


The serviceable block 1 (fig. 293) provides short circuit of an electric chain of the electromagnetic valve 5 with a frequency of rotation of a bent shaft not less than 1000 min.-1 and disconnection of a chain with a frequency no more than 1300 min.-1.
Before check of the block be convinced of reliability of contact connections of system. Operability of the block is checked by means of the voltmeter (with limits of measurement of 0-15 V) and a specialized tachometer. It is undesirable to apply a regular tachometer of the car to check of the EPHH block because of rather big error of its indications.
Disconnect any of two wires from the microswitch, at the same time it is necessary to provide isolation of a wire from "mass" of the car.

Fig. 294. Scheme of check of the EPHH control unit: 1 – EPHH control unit; 2 – a transitional plait with the voltmeter; 3 – burn down the EPHH systems of the car


Connect to the EPHH block the voltmeter by means of a special transitional plait of 2 (fig. 294).
Launch the engine and, smoothly increasing rotation frequency, you monitor indications of the voltmeter:
– after launch of the engine the voltmeter has to show voltage not less than 10 V, and at achievement of frequency of rotation of 1300 min.-1 tension in steps decreases to size no more than 1 V, at the same time the electromagnetic valve is switched-off;
– after shutdown of the valve gradually reduce rotation frequency up to 1000 min.-1, at the same time the voltmeter has to show spasmodic increase in tension not less than up to 10 Century.
It is allowed to check the EPHH block without voltmeter on characteristic click of the electromagnetic valve. Replace the faulty block.

Check of the electromagnetic valve
Malfunction of the electromagnetic valve consists or in break of a winding of the valve (there is no characteristic click at inclusion of ignition), or in leakage of a locking element (at the switched-off valve central and inclined the union are reported). Replace the faulty valve.