On-Board Diagnostic System

DIAGNOSIS
The control unit in the DME can be read out using System Tester 9288 and module version 5.0.

The System Tester is connected to the diagnosis socket located on the left-hand side of the center console.

After the DME control unit has been called up, the following menu selections appear on the display of the system tester:

2 = Actuators

- Injection valve cylinder 1
- Injection valve cylinder 2
- Injection valve cylinder 3
- Injection valve cylinder 4
- Injection valve cylinder 5
- Injection valve cylinder 6
- Idle speed positioner
- Tank vent solenoid valve
- Resonance flap

3 = Switch-Over Inputs

- Engine idle detection
- Full load detection air conditioning compressor
- Reference mark/speed signal
- Heating
- Engaged gear (Tiptronic)
- Timing advance shift (Tiptronic)
- Air conditioning compressor

Menu

1 = Knock registration
2 = Actual values
3 = Drive links active

1 = Knock Registration

The total count of knocks relative to 10,000 ignitions has to be determined during a test drive.

2 = Actual Values

- Voltage at the control unit
- Cylinder head temperature
- Intake air temperature
- Injection time
- Engine rpm
- Vehicle speed
- Timing angle
- Pulse/duty factor of idle speed controller
- Coding
- Load signal
- Voltage of hot film mass air flow sensor
- Voltage of oxygen sensor
- Throttle valve position

3 = Drive Links Active (with Running Engine)

- Injection valve cylinder 1
- Injection valve cylinder 2
- Injection valve cylinder 3
- Injection valve cylinder 4
- Injection valve cylinder 5
- Injection valve cylinder 6
- Auxiliary air pump
- Ignition circuit 1
- Ignition circuit 2

NOTE:
- The operation of both ignition circuits can be tested by alternatively switching off the ignition circuits when the engine is running.

- The operation of the air pump (US specification only) can be checked with the "Auxiliary air pump" menu item.

- With with the air pump working, the system tester displays the oxygen sensor voltage (U-sensor) and operation of the oxygen sensor closed-loop control. The presence of excess oxygen causes a change of the sensor voltage towards 0.1 V and a change of the closed-loop control reading towards to 1.0 V.