Volkswagen Golf Mk3 Ignition System Check: Knock Sensor and Control

Motronic injection and ignition system from 08.95

Motronic injection and ignition system

Checking knock sensor and knock control

Special tools, testers and auxiliary items

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
◆ Test box V.A.G 1598/18
◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
◆ Adapter set V.A.G 1594
◆ Current flow diagram

Test sequence

‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address word" 01. When doing this the engine must be running at idling speed.
(Connecting fault reader and selecting engine electronics control unit .)

→ Indicated on display:

Rapid data transfer HELP

Select function XX

‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

→ Indicated on display:

Read measured value block HELP

Input display group number XXX

‒ Press keys 0, 4 and 5 for "Display group number 45" and confirm entry with Q key.

→ Indicated on display:
(1...4 = Display zones)

Read measured value block 45 ⇒

1 2 3 4

Note:

The check must be carried out during a test drive as the knock control is not active until the engine is loaded for more than 3 ms.

‒ Carry out test drive and when doing this observe specification for knock control on display (2nd person necessary).


	Display zones
	1	2	3	4
Display group 45: Knock control
Display	xx.xx °CS	xx.xx °CS	xx.xx °CS	xx.xx °CS
Indicated	Ignition angle correction cylinder 1	Ignition angle correction cylinder 2	Ignition angle correction cylinder 3	Ignition angle correction cylinder 4
Working range	0.0...15.0 °CS	0.0...15.0 °CS	0.0...15.0 °CS	0.0...15.0 °CS
Specification	0.0...12.0 °CS	0.0...12.0 °CS	0.0...12.0 °CS	0.0...12.0 °CS
	If the specification is not attained , evaluating display group 45

‒ Read-out the readiness code=> Page 01-35 .
‒ Press ⇒key.
‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.

Evaluating display group 45


Display group: 45 Display zones: 1...4	Possible fault cause	Fault elimination
All cylinders more than 12 °CS	Knock sensor defective	- Continuation => Page 28-26
	Connector corroded
	Knock sensor incorrectly tightened	- Loosen knock sensor and tighten to 20 Nm
	Ancillaries on engine loose	- Tighten ancillaries
	Poor fuel quality	- Change fuel type
One cylinder deviates greatly from the others	Connector corroded	- Continuation => Page 28-26
	Engine damage	- Check compression pressures => Repair group 13
	Ancillaries loose on engine	- Tighten ancillaries

Continuation

‒ → Separate blue 3 pin connector -2- to knock sensor 1 (G61) -1-.
‒ Connect multimeter with aux. cables from V.A.G 1594 to measure resistance at contacts 1+2, 1+3 and 2+3 on connector to knock sensor.
Specification ∞ω

If the specification is attained:



‒ → Connect test box V.A.G 1598/18 to control unit wiring loom -arrow-.

‒ → Check wiring between test box and 3 pin connector for open circuit according to current flow diagram.
     Contact 1+socket 34
     Contact 2+socket 33
     Contact 3+socket 56
     Wire resistance: Max. 1.5 ω
‒ Additionally check wires for short to one another.
     Contact 3+socket 34
     Contact 3+socket 33
     Contact 2+socket 34
     Specification: ∞ω

If no wiring fault is detected:

If the fault is still present (fault again in fault memory):

Volkswagen Golf Workshop Service and Auto Repair Manuals