10.3.2. Check of electric motors

The comfort in the car is provided by the electric motors operating window regulators, a sliding roof (hatch), the central lock or the electric antenna more and more.

Each engine turns on the switch and, mostly, manually. In case of the electroantenna, the switch is run automatically by the radio receiver.

1. To check an electric motor safety lock, if necessary to replace.


Electric motors of window regulators and the hatch have safety automatic machines which as a result of excessive loading are switched-off, then, after a while, again turn on. Before new inclusion it is necessary to remove the overload cause. The frozen glasses or the polluted directing glasses can be the reasons.

2. If the safety lock fuses again then somewhere short circuit.
3. At once to find out, the engine is serviceable or not, to connect two additional wires (about 2 mm) from the rechargeable battery of the car directly to the engine. A positive wire to a plus pole, minus a wire to a minus pole of the electric motor. In doubtful cases the arrangement of poles is specified in the electrical circuitry. If necessary the engine can be removed. All electric motors of the car work from tension of onboard network (from 12 to 14 V). If the engine works then there is a break in a current chain.


Slowly rotating engine or at all unrotative, can indicate worn-out graphitic brushes. In this case to replace graphitic brushes.

4. If the engine works, to determine by the electrical circuitry what wire supplies it with current if ignition and the switch is included.
5. To check a control lamp the wire bringing tension to the electric motor. As current is rather big, to check a heat lamp which has sharp needles for piercing of a connecting wire. It is so simpler to check tension. Connecting plugs of electric motors are marked with small figures. They are normirovana:
 – plug 32: connection with weight,
 – plug 33: positive (+) connection.
Engines of the left rotation, for example, of window regulators, have two positive connections:
 – plug 33L: connection of the left rotation,
 – plug 33R: right rotation.


The electric motor of janitors has special designation of plugs (see subsection 10.5).

6. If tension on the engine is absent, the chain is faulty. To find malfunction according to the electrical circuitry and to eliminate. Electric motors, because of big consumption of current, have additional relays of inclusion.
7. If malfunction is not found, to check the switch.
8. If the cable is faulty, then it makes sense to lay a new cable as it is very difficult to find in it break.