Self-diagnosis system (VW Passat B4)

The operating principle of the self-diagnostic system and the method of coding faults are the same as in the diagnostic system used for the fuel injection system "Mono-Jetronic". Only the operations of interrogating the diagnostic system memory device are described below

Injection system fault memory interrogation

This operation can be performed using an LED tester.

In this case, the following order of operations must be strictly observed:

• interrogate storage device;
• eliminate the detected malfunction:
• erase the information in the storage device, since the next survey can only be done after first eliminating the detected malfunction and erasing its code in the storage device;
• make the following poll of the storage device;
• if the fault is not detected, take the vehicle for a test drive for at least 10 minutes and interrogate the memory device again.

The injection system fault memory is interrogated as follows.

Slide the gearshift boot up to access the diagnostic connector terminals. Connect the LED tester wires to the black and blue terminal wires located at the top of the connector. Connect the two test wires to the black and brown (or white) terminals located at the bottom of the diagnostic connector, without connecting these wires to each other. Turn on the ignition. Connect the free ends of the test wires for 4 s, then disconnect them. The LED of the tester should blink. Determine the fault code by the number of blinks of the control lamp (table 2-32).

Clearing information in the fault memory

Connect the free ends of the test wires connected to the lower terminals of the diagnostic connector, then disconnect them. The control LED should light up.

Connect the test leads again for 4 seconds. The test lead LED should show the code "4-4-4-4". This indicates that the previous fault code has been cleared.

Checking electrical circuits

To check the electrical circuits of the KSUD, disconnect the controller connector and use a tester to measure the resistance and voltage values at the terminals of the controller socket. If these values deviate from the norm, first check the corresponding electrical circuit, and then the KSUD element.

Timing advance control subsystem

The ignition timing control subsystem KSUD is a fully electronic ignition system. The controller calculates the optimal ignition timing angle depending on the engine operating conditions (speed, engine load and battery voltage). The ignition advance angle control subsystem generates the corresponding control pulses to interrupt and resume the flow of current in the primary winding of the ignition coil.

The high-voltage current induced in the secondary winding of the ignition coil during the break of the primary winding circuit is supplied through the distributor to the spark plugs. The distributor only performs the function of distributing the high-voltage current to the spark plugs; the Hall sensor built into it supplies the controller with information about the engine speed. The ignition timing control subsystem includes:

• controller.
• ignition distributor with built-in Hall sensor;
• spark timing sensor in cylinder #4;
• two knock sensors;
• ignition unit;
• spark plugs.

The ignition distributor with a built-in Hall sensor is driven by the intake camshaft. Brand and catalog number:

• cars produced before March 1990: Bosch 051 905 205A;
• cars produced since April 1990: Bosch 051 905 205B.

The original can be viewed on the portal: www.VWManual.ru

Setting ignition timing angle before TDC at idle: 5-7°,

Resistance of the primary winding of the ignition coil at 20UC 0.6-0.8 Ohm. Resistance of the secondary winding at 20°C 6.5-8.5 kOhm.

Brand and type of spark plugs: Bosch F6 DTC; Champion C6 BYC; Vegi 14F 6DTU. The gap between the electrodes is 0.7-0.9 mm.