Features of MAZ electrics

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The electrical system of the MAZ car has a rated voltage of 24 V. The vehicle's on-board network is made according to a single-wire circuit

The negative terminal of the batteries (AB) is connected to the ground of the vehicle (frame, power unit, generator and cabin) through a ground switch. The positive terminal of the battery is connected to the vehicle's on-board network through a 60 A main fuse.

Connected using a two-wire circuit:

— portable lamp socket in the cabin
— cab lighting
— heater fan electric motors
— independent heater
— tachograph

The main fuse is designed to protect the battery and generator from short circuit and polarity reversal when starting the engine from an external source and is not further considered as a fuse. (On cars with MAN engines, the 60 A fuse is shunted by a jumper with a cross-section of 2.5 mm2, so it does not perform short circuit (short circuit) and polarity reversal protection functions, but is used as a connecting panel for wiring).

All electrical consumers are powered from a 60A fuse (on the generator connection side) (with the exception of the alarm system, which is directly connected to the battery) and additionally have their own fuses.

The starter and instrument switch, main light switch, starter relay and ground switch winding do not have fuses.

All fuses are located in three blocks:

— fuses 60 A and 30 A, 1 piece each — in block 111.3722
- 6 A fuses - 21 pcs - in fuse and relay blocks 23.3722; 23.3722-01; 23.3722-02; 23.3 722-03
— fuses 16 A – 1 pc. and 8 A - 9 pcs. - in fuse block PR 112.

The purpose of fuses (stripped circuits) and their ratings are indicated in the tables:

Assignment of fuses in block 111.3722

60 A – main fuse

30 A – power supply of independent heater, PZD technological equipment

Assignment of 6 A fuses in fuse and relay blocks 233722, 233722-01, 233722-03

No. - No. - wires - power circuit

1 - 127 - Parking brake warning lamp relay, voltage indicator, speedometer, tachograph
2 - Sound signals
3 - 57 - Brake lights
4 - 90 - Windshield wiper, washer
5 - 120 - Reversing lights, center and wheel locks, engine light, semi-trailer steering axle lock, hitch light
6 - 162 - Mirror heaters, trailer tail lights
7 - Power supply for on-board control system
8 - P51 - Instrument lighting
9 - 55 - Fog lights
10 - Kch.52 - Right side lights
11 - G.52 - Left side lights
12 - F.56 - Low beam (left headlight)
13 - Ж.56 - Low beam (right headlight)
14 - 53 - Additional high beam headlights
15 - K.54 - High beam (right headlight)
16 - Z.54 - High beam (left headlight)
17 - G.80 - Heater fan
18 - Zh.79 - Emergency signaling
19 - K.78 - Direction indicators
20 - P.31 - Indicator lamps, indicators (instruments) of the main panel
21 - 50 - Rear fog lights

Purpose of fuses in the PR 112 block

No. - rating - power circuit:

- 16A - Reserve, technological equipment;
- 8A - Cooling system fan clutch;
- 8A - Body lighting, heater control unit 15.8106-01 or Webasto;
- 8A - Fuel heaters;
- 8A - Radio tape recorder, timer;
- 8A - Cabin lamps;
- 8A - Portable lamp socket in the cabin, pneumatic signal, refrigerator;
- 8A - Reserve;
- 8A - Level sensors, air dryer, additional instrument panel, process equipment;
- 8A - Engine stop valve

Purpose of relays located in blocks 23.3722, 23.3722-01, 23.3722-02, 23.3722-03

Relay type 901.3747-11

Relay No. - Consumers
K1 - Sound signals
K2 - Reversing lights
K3 - Ground switch interlock
K4 - Brake lights
K5 - On-board control system 23.3722, 23.3722-02
K6 - Low beam headlights
K7 - Blocking additional high beam headlights
K8 - Side lights
K9 - High beam headlights
K10 - Electric torch device (shunt resistance)
K11 - Electric torch device (generator blocking)

Location of electrical equipment products

Name - Location

Sensor for turning on the cross-axle differential lock warning lamp VPST (MM 125D) - On the beam of the middle and rear axles

Sensor for turning on the cross-axle differential lock ala (MM 125) - On the pneumatic cylinder for locking the middle axle and the transfer case

Valve for turning on the cross-axle differential lock KEM-07 (P30.131.01) - On the left side member in the area of the rear axle

Valve for turning on the center differential lock KEM-07 (P30.131.01) - On the left side member in the area of the middle axle

Sensor for turning on the parking brake warning lamp DADV (MM124D) - On two main valves of the parking brake drive

Emergency air pressure sensors in the pneumatic brake system DADV (MM124D) - On the receivers of the front and rear circuits of the pneumatic system or on the brake sensor block

Air pressure sensors in the pneumatic brake system MM370 - On the receivers of the front and rear circuits of the pneumatic system or on the brake sensor block

Brake signal sensors – VPST (MM125D) - On the brake valve, on the trailer brake control valve or on the brake sensor block

Engine stop electromagnet 15.3747, PC330 - Outside, on the front panel of the cab, on the left under the trim

Electrovalve for pneumatic signal 16.3741 - Outside, on the left base of the cab

Turn relay RS951A, PEUP6 - In the cabin under the additional instrument panel

Electric wiper motor 13.5205 - Inside the cab, on the front panel of the cab, on the right

Electric washer motor - On the washer reservoir

Fuse and relay block 23.3722; 23.2722-01; 23.3722-03; 23.3722-04 - In the cabin, in the central part, under the hinged panel cover

Wiper breaker relay 461.3747 - On the fuse and relay box

Range multiplier blocking relay 6312.3747 - In the cab on the right, under the hinged instrument panel cover, under the hinged fuse and relay panel

Fuse box Pr112 - In the cab on the right, under the hinged cover of the instrument panel.

Fuse block 111.3722; Starter relay 738.3747-20; Additional resistance EFU_12.3741000; Flashlight FP12G; Alarm relay 733.3747-10; Parking brake warning lamp relay RS493; Portable lamp socket - On the hinged fuse and relay panel

Electrical connectors (connection of rear light harnesses) - In the junction box, at the rear of the left side member

Electrical connectors (connection of side turn signal harnesses) - Inside the instrument panel, left and right

Electrical connectors (connection of side marker light harnesses) - In the junction box, at the rear of the left side member

Electrical connector X62 (battery switch connection) - In the battery container

The electrical connection diagram is “MAZ electrical harness diagram”

Possible malfunctions of electrical equipment and solutions

Cause (Remedy)

Sound signals do not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness. Check the fuse for serviceability. If the fuse is faulty, eliminate the short circuit in the circuit, replace the fuse

- The steering column switch is faulty

Check the functionality of the switch, replace if necessary

- Switching relay is faulty

Check the functionality of the relay, replace the relay if necessary

- Sound signals are faulty

Check the functionality of the signals, replace if necessary

Cab lighting does not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness. Check the fuses for serviceability. If the fuse is faulty, eliminate the short circuit in the circuit and replace the fuse. Replace pump

The engine light does not work:

- open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness. Check the serviceability of the fuse; if the fuse is faulty, eliminate the short circuit in the circuit, replace the fuse

- The lamp switch is faulty

Check the functionality of the switch, replace if necessary

- Destruction of the filament

Replace lamp

Pneumatic signal does not work:

- Valve circuit open, short circuit. The steering column switch is faulty

- Valve faulty

Check the valve for serviceability, replace if necessary

Heated mirrors do not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness. Check the fuse for serviceability. If the fuse is faulty, repair the short circuit in the circuit and, replace the fuse.

- The heated mirror switch is faulty

Check the functionality of the switch, replace if necessary

- Heating element is faulty

Check the functionality of the heating element, replace if necessary

Reverse lights do not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness.

- The reverse signal sensor is faulty

Check the functionality of the sensor, replace if necessary

- Switching relay is faulty

Check the functionality of the relay, replace the relay if necessary

- Destruction of the lamp filament

Replace lamp

The cross-axle differential lock valve does not work:

- Open circuit, short circuit

- Switch is faulty

Check the functionality of the switch, replace if necessary

- Valve faulty

Check the functionality of the valve, replace if necessary

center differential lock valve does not work

- Open circuit, short circuit

Brake lights do not work:

- Switch is faulty

Check the functionality of the switch, replace if necessary

- Valve faulty

Check the functionality of the valve, replace if necessary

- Open circuit, short circuit

- Brake light switch is faulty

Check the functionality of the sensor and replace it if necessary.

High or low beam headlights and corresponding warning lamps do not work:

- Switching relay is faulty

Check the functionality of the relay, replace if necessary

- Destruction of the lamp filament

Replace lamp

The main light switch is faulty. The steering column switch is faulty:

Check the reliability of contact in the detachable connections.
Check the integrity of the wiring harness.
Check the fuse for serviceability. If the fuses are faulty, eliminate the short circuit in the circuit, replace the fuse
Check the functionality of the switch, replace if necessary

- Open circuit, short circuit

Check the functionality of the switch, replace if necessary

Parking lights do not work**:

- Switching relay is faulty

Check the functionality of the relay, replace if necessary

- Destruction of the lamp filament

Replace lamp

- Main light switch is faulty

- Open circuit, short circuit

Check the functionality of the switch, replace if necessary

Rear fog lights and warning lamp do not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness. Check the fuses for serviceability. If the fuses are faulty, eliminate the short circuit in the circuit, replace the fuse

- The main light switch is faulty.

Check the functionality of the switch, replace if necessary

The rear fog light switch is faulty:

- Destruction of the lamp filament

Check the functionality of the switch, replace if necessary

Replace lamp

- Switching relay is faulty

Check the functionality of the relay, replace the relay if necessary

- Destruction of the lamp filament

Replace lamp

The direction indicators do not turn on:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness.

- The steering column switch is faulty

Check the functionality of the switch, replace if necessary

- Faulty relay breaker The RS951 relay has automatic protection against short circuit (short circuit). When there is a short circuit in one of the sides, the relay turns off the direction indicators

PEUP6 has four independent channels: LB of the tractor, PB of the tractor, LB of the trailer, PB of the trailer. In the event of a short circuit in one of the channels, the rest remain operational

Check the functionality of the breaker relay, replace if necessary

- Hazard switch is faulty

Check the operation of the emergency light switch, replace if necessary

- Destruction of the lamp filament

Replace lamp

Indicator lamps for the direction indicators of a tractor or trailer do not light up when the PC95IA relay is working (clicks are heard) and relay/PEUP6 (the buzzer is buzzing)

Open circuit in the control or signal lamp circuits of the direction indicators:

- Broken threads of control or signal lamps

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness

Replace lamps

The door opening buzzer does not work when the rear fog lights are on and the starter and instrument switch key is removed:

- Open circuit, short circuit

Check the fuse for serviceability. If the fuse is faulty, eliminate the short circuit in the circuit, replace the fuse

- The rear fog light switch is faulty

Check the functionality of the switch, replace if necessary

- Limit switch is faulty

Check its functionality and, if necessary, replace it

- Alarm relay is faulty

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness. Check the fuse for serviceability.

If the fuse is faulty, eliminate the short circuit in the circuit and replace the fuse

- The gap between the left door and the doorway in the area where the limit switch is installed has been increased

Adjust the gap in the doorway or adjust the limit switch

Check the functionality of the switch, replace if necessary

The windshield wiper does not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness.

Check the fuse for serviceability. If the fuse is faulty, eliminate the short circuit in the circuit, replace the fuse

- The steering column switch is faulty

Check the functionality of the switch, replace if necessary

- The windshield wiper relay is faulty

Check the functionality of the breaker relay, replace if necessary

- The windshield wiper motor is faulty

Check the operation of the gear motor and replace it if necessary

The windshield wiper motor is overloaded. When turned on, a noise and grinding noise is heard, then it turns off (the thermal fuse has tripped):

- The rods engage with the cabin parts

Ensure clearance between rods and cabin parts

- The rods are jammed, the brushes are frozen

Ensure clearance between the rods and cabin parts, eliminate freezing

The windshield washer does not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness.

Check the fuse for serviceability. If the fuse is faulty, eliminate the short circuit in the circuit, replace the fuse

- The steering column switch is faulty

Check the functionality of the switch, replace if necessary

- The windshield washer pump is faulty

Check the operation of the pump, replace if necessary

Indicators do not work: fuel level, pressure, coolant temperature, pressure in the pneumatic system*:

- Open circuit, short circuit. Sensors are faulty

Check the reliability of contact in the detachable connections.
Check the integrity of the wiring harness.
Check the serviceability of fuses F20, F9. If the fuses are faulty, eliminate the short circuit in the circuit and replace the fuses.
Check the functionality of the sensors, replace if necessary

Tachometer does not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness.

Check the serviceability of fuse F20. If the fuse is faulty, eliminate the short circuit in the circuit, replace the fuse

- The tachometer is faulty. Open circuit from terminal “~” of the generator to the tachometer
- Generator faulty

Replace tachometer

Check the circuit in the wiring harnesses from the generator to the tachometer

Brake warning lamp flashing mode does not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness.

Check the fuse for serviceability. If the fuse is faulty, eliminate the short circuit in the circuit and replace the fuse

- The relay-breaker of the warning lamp is faulty

Check the serviceability of the breaker relay, if faulty, replace it

- Parking brake sensor is faulty

Check the sensor for serviceability; if faulty, replace it

Heater motors do not work:

- Open circuit, short circuit

Check the connections for reliable contact. Check the integrity of the wiring harness.

Check the fuse for serviceability. If the fuse is faulty, eliminate the short circuit in the circuit, replace the fuse

- Switch is faulty

Check the switch for serviceability; if faulty, replace it

- Electric motor is faulty

Check the serviceability of the electric motor; if faulty, replace it

Indicator lamps do not work: air pressure, emergency pressure, air clogging of differential locks:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness.

Check the serviceability of fuses F20, F9. If the fuses are faulty, eliminate the short circuit in the circuit, replace the fuses

- Malfunction of the corresponding sensors

Check the serviceability of the sensors; if faulty, replace them

- Destruction of the filament of the corresponding control lamp

Replace the warning lamp

Dehumidifier not working:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harnesses.

Check the fuse for serviceability. If the fuse is faulty, eliminate the short circuit in the circuit, replace the fuse

- Air dryer is faulty

Check the serviceability of the dryer; if faulty, replace it

The socket in the cabin does not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness.

Check the fuses for serviceability. If the fuse is faulty, eliminate the short circuit in the circuit and replace the fuse

The radio does not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness.

Check the fuses for serviceability. If the fuses are faulty, eliminate the short circuit in the circuit, replace the fuse

- The radio is faulty

Check that the radio is working properly.

The starter does not turn on:

Open circuit, short circuit. The intermediate starter relay is faulty. The starter and instrument switch is faulty. Starter faulty

Check the reliability of contact in detachable connections. Check the integrity of the wiring harness
Check the serviceability of the intermediate starter relay, replace if necessary
Check the serviceability of the starter switch and instruments; if faulty, replace

When the mass is turned on, the voltage arrow remains in place:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness.

Check the serviceability of fuse F1. If the fuse is faulty, eliminate the short circuit in the circuit, replace the fuse

When the engine is running, the generator set health indicator light is on:

- Generator faulty

Repair or replace the generator.

The ground switch does not turn on from the cab:

- Circuit break. The power button is faulty

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness

- Short circuit switching relay is faulty

Check the button for serviceability; if faulty, replace it

- Burnt battery switch contacts

Check the serviceability of the relay, if faulty, replace it. Clean the switch contacts

Speedometer does not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check the integrity of the wiring harness.

Check the fuse for serviceability. If the fuse is faulty, eliminate the short circuit in the circuit, replace the fuse

- Speedometer is faulty

Check the serviceability of the speedometer, if faulty, replace it

- Sensor faulty

Check the sensor for serviceability; if faulty, replace it

Illumination lamps - indicators and switches do not work:

- Open circuit, short circuit

Check the reliability of contact in the detachable connections. Check integrity of the wiring harness.

Check the fuse for serviceability. If the fuse is faulty, eliminate the short circuit and replace the fuse

- Backlight rheostat is faulty

Check the functionality of the backlight rheostat

- Side light switching relay is faulty

Check the relay for serviceability, replace if faulty