Checking the performance of the control unit 25.3761
Scheme of the pneumatic valve control system of the carburetor type «Ozone»
1 - microswitch in the carburetor; 2 – electropneumatic valve; 3 - mounting block; 4 - ignition relay; 5 - ignition switch; 6 – electropneumatic valve control unit; 7 - ignition coil; A - to the conclusion "30" generator; B - the order of conditional numbering of plugs in the control unit
Scheme for checking the pneumatic valve control unit
1 - control unit; 2 - transitional connector with a voltmeter; A - car wiring harness
A working control unit 25.3761 should turn off the pneumatic valve 2 (see fig. Scheme of the pneumatic valve control system of the carburetor type «Ozone») with an increase in the engine crankshaft speed up to 1600 min-1 and turn on the pneumatic valve when the speed is reduced to 1200 min-1.
1. Before checking the operation of the unit, you must make sure that the vehicle wiring harness is connected to the control unit correctly (see view of the control unit connector, fig. Scheme of the pneumatic valve control system of the carburetor type «Ozone»).
2. The performance of the control unit is checked using a tachometer and a voltmeter (with measurement limits 0–15 V) in the following order:
- disconnect the wires from the microswitch mounted on the carburetor;
- connect to control box 1 (see fig. Scheme for checking the pneumatic valve control unit) voltmeter using a special adapter connector 2;
- start the engine and, gradually increasing the speed, monitor the voltmeter readings: after starting the engine, the voltmeter should show a voltage of at least 10 V, and at the moment the pneumatic valve is turned off, an abrupt decrease in voltage to a value of no more than 1.5 V;
- after turning off the pneumatic valve, gradually reduce the speed until the valve is turned on: the voltmeter should show an abrupt increase in voltage to at least 10 V.
Attention! It is allowed to check the operability of the unit without a voltmeter and adapter by the characteristic knock of the pneumatic valve when turning it off and on, respectively, during a smooth increase and decrease in the engine crankshaft speed.
Checking the solenoid valve control unit
Addresses of the output terminals of the solenoid valve control unit
Terminal | Address |
1 | To ignition coil terminal |
2 | Weight |
3 | – |
4 | +12V from terminal "15" ignition switch |
5 | Carburetor limit switch |
6 | Solenoid valve carburetor |
7 | – |
If the engine has a carburetor 21051-1107010, then instead of the control unit 21.3761 for the pneumatic valve, the control unit 501. 3761 for the carburetor solenoid valve is installed.
The control unit 501.3761 must turn off the valve at a crankshaft speed of 1900 min-1, and turn on at 1700 min-1. The addresses of the output terminals of the block are indicated in the table Addresses of the output terminals of the solenoid valve control unit.
The performance of the solenoid valve control unit is checked using a tachometer and a voltmeter (with measurement limits 0–15 V).
1. Disconnect the white-black wire from the carburetor limit switch and connect the tip of this wire to ground.
2. Connect adapter with voltmeter (similar to that shown in Fig. Scheme for checking the pneumatic valve control unit) between the block of the additional harness and the block.
3. Start the engine and, gradually increasing the speed, monitor the voltmeter readings: after starting the engine, the voltmeter should show a voltage of at least 10 V, and at the moment the valve is turned off, an abrupt decrease in voltage to a value of no more than 0.5 V.
4. After turning off the valve, gradually reduce the speed until the valve is turned on: the voltmeter should show an abrupt increase in voltage of at least 10 V.
5. Set the crankshaft speed within 2200–2300 min-1, disconnect the tip of the wire going to the carburetor limit switch from the ground, and then reconnect it to the ground. When the wire is disconnected from ground, the valve should turn on, and when connected to ground, it should turn off. It is allowed to check the unit without a voltmeter by the characteristic knock of the valve when turning it off and on.