Audi A4

since 1994 release

Repair and operation of the car

Central lock

Emergency unblocking of a cover of a fuel tank at malfunction of the central lock: remove facing of a luggage carrier on the right, cast away an insulating plate (2), press a fixing clamp (1) servomotor of the central lock and extend an executive element back.

All doors, trunk lid and cover of a fuel tank, and also the lock in a trunk lid open and closed by turn of a key in the lock of a door of the driver or in the lock of a door of the passenger near the driver. The main link of system is the so-called double delivery pump which is given by the electric motor. At turn of a key in situation "openly" the pump creates an elevated pressure therefore various switching elements in the car remove the operating blocking.

With the double delivery pump the control unit of the central lock, and also the control unit of pritivougonny system if it is installed in the car is combined.

Further the serial central lock is described. Functions of more expensive systems with anticreeping installations, protection of salon, infrared remote control (see also head the Electrotechnical equipment) in the main function are also based on this system, as well as "the central lock of safety".

Council: Feature of the lock of a luggage carrier: in vertical position of the lock of a luggage carrier – irrespective of the central lock – it is always closed. It does not allow opening of a luggage carrier by quick thieves at a stop on the traffic light. In horizontal situation the lock of a luggage carrier reacts to the central blocking absolutely normally.

Check of the central lock

PERFORMANCE ORDER

Or a trunk lid close a door of the driver and passenger near the driver and open a key.
The central lock has to become more active from all three locks.
Approximately in two seconds all locks have to be blocked.
If the pump works more long than five seconds, the system is not tight – in this case the double delivery pump can work at most 35 with after that it has to be switched-off.

Council: If once the central lock failed, doors and a trunk lid can be opened and closed, as usual, a key. In the same way buttons of blocking of doors can be put in action manually. Only the cover of a fuel tank needs to be deblocked separately: to dismantle the right facing of a luggage carrier. Press on a fixing clamp of a servomotor of the central lock of a cover of a fuel tank and extend an executive element back.

Search of malfunctions in the electrician

The description given below also belongs to cars with the standard central lock. Electric check is carried out on 6-and the 12-polar shtekerny socket on the double delivery pump. In cars with anticreeping system there is one more 16-polar socket on the pump which when checking remains unaddressed.

If the pump does not work at turn of a key in the lock of a door of the driver and passenger near the driver, in the luggage carrier lock:

PERFORMANCE ORDER

Check a safety lock.
Dismantle facing of a luggage carrier behind and on the right side; the double delivery pump is on the right below near a bottom of a luggage carrier and is packed into polyfoam.
"Unpack" the double delivery pump.

Important: in the beginning disconnect from the pump the mnogoshtyrkovy socket(s) with thin wires – in the end I will corrode with a thick wire (giving of current).
Remove a cover of the 12-shtyrkovy socket
Check of the switching element at the driver's doors: connect a control lamp to the socket between contact of a green/blue wire and mass of a body.
The control lamp has to burn constantly if the door of the driver opens a key. In this case the disconnecting contact as it should be.
If the lamp does not light up, at doors of the driver the disconnecting contact or not conductivity in the bringing wire is faulty.
Switch a control lamp: instead of weight one of contacts of a control lamp is connected to "+" the accumulator. Other contact remains connected to the socket (contact of a green/blue wire).
Close the driver's door a key.
If now the control lamp burns constantly, the closing contact of the switching element as it should be.
If the lamp does not light up and there is no defect in a wire, the switching element is faulty.
Check of the switching element at the passenger's doors near the driver: in the disconnected socket of the pump connect a control lamp between contact of a yellow/blue wire and mass of a body.
The control lamp has to burn constantly if the passenger's door near the driver opens a key. In this case the disconnecting contact of the switching element as it should be.
If the lamp does not light up, at the passenger's doors near the driver the disconnecting contact or not conductivity in the bringing wire is faulty.
Switch a control lamp: instead of weight one of contacts of a control lamp is connected to "+" the accumulator. Other contact remains connected to the socket (contact of a yellow/blue wire).
Close the passenger's door near the driver a key.
If now the control lamp burns constantly, the closing contact of the switching element as it should be.
If the lamp does not light up and there is no defect in a wire, the switching element is faulty.
Check of the switching element in the luggage carrier lock: in the disconnected socket of the pump connect a control lamp between contact of a blue/red wire and "+" the accumulator.
The control lamp has to burn constantly if the lock of a luggage carrier opens a key. In this case the disconnecting contact of the switching element as it should be.
If the lamp does not light up, in the lock of a luggage carrier the disconnecting contact or not conductivity in the bringing wire is faulty.
Switch a control lamp: instead of a blue/red wire now one of contacts of a control lamp is connected to a gray/white wire. Other contact remains connected to "+" the accumulator.
Close the luggage carrier lock a key.
If the control lamp burns constantly while the key remains in situation "is closed", the closing contact of the switching element as it should be.
If the lamp does not light up and there is no defect in a wire, the switching element is faulty.
Check of the double delivery pump: if work of the switching elements of the pump is guaranteed checked), a cause of defect there is only a giving of current (on a thin red wire in the 12-shtyrkovy socket, and also on a thick red/blue wire or a thin red/black wire in the small 6-shtyrkovy socket) and connection with weight (a thick brown wire).
If everything is all right, the double delivery pump is faulty. Replace.

Here details of laying of a hose of the central lock are visible


1 – hose; 2 – the switching element of a door of the passenger near the driver; 3 – connecting detail; 4 – the switching door element on the right behind; 5 – a branch detail under a back seat;	6 – the switching element of a door of a cover of a fuel tank; 7 – double delivery pump; 8 – the switching trunk lid element; 9 – the switching door element at the left behind; 10 – the switching element of a door of the driver.

The double delivery pump (2) of the central lock is put under the right facing of a luggage carrier. Here it "is taken out" from the cover from polyfoam (1). Further you see: electric wires (4) and a delivery/vacuum hose (3) to the switching elements.

Under a back seat the central delivery/vacuum hose branches on a plait to the right doors (1) and on a plait to the left doors (2).

Search of malfunctions in pneumatic system

PERFORMANCE ORDER

For verification of leakage in the central lock (a sign: the double delivery pump works too long) it is necessary to check all system consistently.
Double delivery pump: directly at the pump squeeze a hose flat-nose pliers and thus densely block. Put one of locks in action.
If the double delivery pump at activization of the central lock works more long than 3, max. 7 pages, the pump is not tight. Replace it.
The switching elements in the doorway and covers: serially press all hoses directly about the switching elements. For this purpose dismantle the corresponding facings (the head Detali of a body). Every time make active one of locks.
The double delivery pump at activization of the central lock should not work more long than 3, max. 7 pages.
After a detachment of defective (not tight) knot the pump works normally, i.e. less than 3 pages. Replace a faulty detail.

Council: In order that at a detachment of hoses not to dismantle all facing, it is possible to press hoses at branch – in the beginning burn down to the right doors, then to the left doors.