Timing Components: Testing and Inspection

Camshaft adjustment, checking

The adjustment of intake camshafts is load - and RPM dependent. Oil pressure is switched to respective camshaft adjuster (mechanical adjustment devices) via solenoid valve for camshaft adjustment.

Note:
^ Camshaft adjustment is active only 25 seconds after engine start.

Solenoid valves for camshaft adjustment, checking





Special tools, testers and auxiliary items required

^ Hand multimeter V.A.G 1526 B or V.A.G 1526 A
^ Voltage tester V.A.G 1527 B
^ Connector test kit V.A.G 1594 C or V.A.G 1594 A
^ Test box 1598/31
^ Vehicle Diagnostic, Testing and Information System VAS 5051 A with diagnostic cable VAS 5051/1

Preparation

Cylinder bank 1 (right):





- Disconnect electrical harness connector -3- to Camshaft Adjustment Valve 1 N205.

Cylinder bank 2 (left):





- Remove coolant expansion tank bolt - arrow -.
- Disconnect electrical wire from Engine Coolant Level (ECL) Warning Switch F66 and set aside coolant reservoir with coolant hoses -1- and -2- connected.





- Disconnect electrical harness connector -2- to Camshaft Adjustment Valve 2 N208.

Checking internal resistance





- Connect multimeter to valve for resistance measurement.

^ Specification: 8 to 13 ohms.

If specification is not obtained:

- Replace valve.

If specified value is not achieved:

Checking voltage supply

^ Fuse for valve for camshaft adjustment is OK Electrical Wiring Diagrams, Troubleshooting and Component Locations.
^ Motronic Engine Control Module (ECM) Power Supply Relay J271 OK.

Note:
^ Voltage for camshaft adjustment valves is supplied via Motronic Engine Control Module (ECM) Power Supply Relay J271.





- Connect voltage tester V.A.G 1527 B as follows:





- Operate starter briefly.

^ LED must light up.

If LED does not light up:

- Check wire connection from terminal 1 of electrical harness connector via fuse to Motronic Engine Control Module (ECM) Power Supply Relay J271 for open circuit according to wiring diagram.
- Repair wire connection if necessary.

If LED lights up:

Check activation





- Connect voltage tester V.A.G 1527 B to terminals -1- (B+) and -2- of electrical harness connector.
- Connect Vehicle Diagnostic, Testing and Information System VAS 5051 and select vehicle system "01 - engine electronics". Ignition must be switched on Guided Fault Finding in VAS 5051.





Display on VAS 5051:

- In selection -1-, click on the function "03 - output Diagnostic Test Mode (DTM)".
- Press -> button repeatedly until Camshaft Adjustment Valve 1 N205 is activated.

^ LED must blink.

- Press -> button repeatedly until Camshaft Adjustment Valve 2 N208 is activated.

^ LED must blink.

- End function "03 - output Diagnostic Test Mode (DTM)" by pressing <- button.
- Select "06 - End Output".
- Switch off ignition.

If LED does not blink or it remains lit:





- Connect test box V.A.G 1598/31 to wiring harness connectors, Engine Control Module (ECM) is not connected. Connect Ground (GND) clip at test box (not visible in illustration) to Ground (GND).

CAUTION: To avoid damaging electronic components, set measuring range before connecting test leads and observe all test requirements.





- Check following wire connections for open circuit and short circuit to Ground (GND) and B+:

^ Camshaft Adjustment Valve 1 N205





^ Camshaft Adjustment Valve 2 N208





- Repair wire connection if necessary.

If wiring connection is OK:

- Replace Engine Control Module (ECM).

If no malfunctions are detected:

- Replace mechanical camshaft adjuster.