Knock Sensor and Knock Sensor System, Checking

Knock Sensor And Knock Sensor System, Checking

Required special tools and test equipment
- VAG 1551/1552 Scan Tool (ST) with adapter cable VAG 1551/3
- VAG 1598/22 test box
- Multimeter US 1119 (Fluke 83 or equivalent)
- VW 1594 connector test kit
- Wiring diagrams

Checking
- Connect VAG 1551/1552 Scan Tool (ST) and press buttons -0- and -1- to insert "Engine Electronics" address word O1 (engine running at idle). Connecting VAG 1551/1552 Scan Tool

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08, and press -Q- button to confirm input.

Indicated on display

Read Measuring Value Block HELP
Input display group number XXX

- Press buttons -0-, -2- and -0- to input display group number 20, and press -Q- button to confirm input.

Indicated on display (1-4 = display groups)

Read Measuring Value Block 20 ->
1 2 3 4

NOTE: The test must be carried out during a road test because the knock sensor system is only active as of a certain engine speed.

- Road test car and compare display with specified values for knock sensor system in display field 1-4.

WARNING!
A second technician is required to operate the VAG 1551 scan tool during the road test.

Display Group 20:

If displayed values are OK:
- Check readiness code. If Diagnostic Trouble Code (DTC) memory has been erased, or ECM was disconnected, generate new readiness code.
Readiness Code Reading
Readiness Code, Generating
- Press -> button to advance program sequence.
- Press buttons -0- and -6- to select "End Output" function 06, and press -Q- button to confirm input.

Display Field 1 - 4:

Continuation
- Disconnect 3-pin connector from Knock Sensor (KS) 1 -G61-.

- Connect multimeter US 1119 (Fluke 83 or equivalent) to measure resistance between connector terminals, using adapter cables from VW 1594 connector test kit.
- Connector terminal 1 to terminal 2
- Connector terminal 1 to terminal 3
- Connector terminal 2 to terminal 3
- Specified value: Infinity Ohms

If resistance is OK (no continuity):
- Connect VAG 1598/22 test box to Motronic ECM harness connector. Connecting VAG 1598/22 Test Box

- Check wiring for open circuit between ECM/test box and 3-pin harness connector, according to wiring diagram.
- Connector terminal 1 to ECM/test box socket 68
- Connector terminal 2 to ECM/test box socket 67
- Connector terminal 3 to ECM/test box socket 2
- Specified value: max. 1.5 Ohms

- Check wiring for short circuits between terminals of 3-pin connector, and between connector and ECM/test box.
- Connector terminal 2 to ECM/test box socket 68
- Connector terminal 3 to ECM/test box socket 68
- Connector terminal 3 to ECM/test box socket 67
- Specified value: Infinity Ohms

If the wiring is OK:
- Loosen knock sensor and re-tighten to 20 Nm (15 ft lb).

If the malfunction still exists (stored in DTC memory):
- Replace Knock Sensor (KS) 1 -G61-.
- Check readiness code. If Diagnostic Trouble Code (DTC) memory has been erased, or ECM was disconnected, generate new readiness code.
Readiness Code Reading
Readiness Code, Generating
- Disconnect 3-pin connector from Knock Sensor (KS) 2 -G66-.

- Check wiring for open circuit between ECM/test box and 3-pin harness connector, according to wiring diagram.
- Connector terminal 1 to ECM/test box socket 60
- Connector terminal 2 to ECM/test box socket 67
- Connector terminal 3 to ECM/test box socket 2
- Specified value: max. 1.5 Ohms

- Check wiring for short circuits between terminals of 3-pin connector, and between connector and ECM/test box.
- Connector terminal 2 to ECM/test box socket 60
- Connector terminal 3 to ECM/test box socket 60
- Connector terminal 3 to ECM/test box socket 67
- Specified value: Infinity Ohms

If the wiring is OK:
- Loosen knock sensor and re-tighten to 20 Nm (15 ft.lb)

If the malfunction still exists (stored in DTC memory):
- Replace Knock Sensor (KS) 2 -G66-.
- Check readiness code. If Diagnostic Trouble Code (DTC) memory has been erased, or ECM was disconnected, generate new readiness code.
Readiness Code Reading
Readiness Code, Generating