Test point 33 Leads K and L

The diagnosis connection between the DME control unit and testers is established by means of the two leads K and L. If no diagnosis is possible, the following points must be checked:

1. Continuity test (refer to wiring diagram)

Leads L: Pin 7 (19-pin diagnostic socket)

Leads K: Pin 8 (19-pin diagnostic socket)

2. Ground short test (refer to wiring diagram)

Leads L: The voltage at pin 7 (19-pin diagnostic socket) must be > 8 V when the ignition is on.

Lead K: The voltage at pin 8 (19-pin diagnostic socket) must be > 8 V when the ignition is on

Porsche 9288 Tester
951 - 24/28


10 - Ground

13 - Terminal 15

Possible fault cause at < 8 Volt:

- Short to ground or open circuit in wiring or connectors

- A defective control unit connected to the above leads. (May be any diagnosable control unit, need not necessarily be the DME control unit).

Checking: Disconnect plugs at diagnosable control units one after the other until the voltage is > 8 V. Replace responsible control unit.

- Tester faulty.

- No power supply at the diagnostic plug.

- No ground supply at diagnostic plug.

Notes on idling speed and idling CO testing:

a) Idling speed

Idle speed check value for engines at operating temperature:

840 ± 40 rpm with manual transmission 880 ± 40 rpm with Tiptronic b) Idle speed CO of cars without catalytic converter

The CO level is adjusted at the idle potentiometer in the engine compartment. The following requirements must be observed:

- Engine at operating temperature

- Engine in good mechanical condition, ignition o.k.

- All loads switched off

- CO tester at operating temperature, calibrated and adjusted correctly

c) Idle speed CO of cars with catalytic converter

On these vehicles, adaptation of idle speed CO level takes place along with adaptation of the idle speed. As a result, only the actual condition can be checked on those vehicles. The following requirements must be observed when performing the checks:

- Engine at operating temperature

- Engine in good mechanical condition, ignition o.k.

- All loads disconnected

- Exhaust tester at operating temperature, calibrated and adjusted correctly

- Oxygen sensor plug connected Test value: 0.4 -1.2 % CO

After disconnecting the control unit plug or the battery, the engine must run at idle for at least 10 minutes before these values can be rechecked.

Coding the control unit

The DME control unit is coded using a jumper connection deviating from the control unit wiring loom. If the jumper connection is free, the control unit operates in controlled mode, i.e. with oxygen sensor regulation. If a 1 kQ resistor is attached to the jumper, the control unit operates in uncontrolled mode, i.e. without oxygen sensor regulation.

The coding may also be read directly in the "Actual values" menu item using System Tester 9288.

Check-Engine Lamp (Malfunction indicator Light M.I.L.)

USA vehicles are fitted with with a warning lamp that lights up if a component relevant to exhaust gas composition fails.

As a function check of the warning lamp, the lamp lights up when the ignition is switched on and goes out when the engine is running after it has been started without depressing the accelerator.

A flashing code of the warning lamp indicates the defective fault path.

To trigger the flashing code, fully depress the accelerator pedal for 3 seconds with the engine off and the ignition on until the Check-Engine lamp flashes. Then ease off the throttle.

If no fault is stored, i.e. no warning came from the warning lamp, a flashing code appears

no fault.

If the warning lamp did indicate a warning, i.e. there is a fault, a flashing code appears, e.g. 112 4

Fault code

Constant fault (2 with loose contact) DME



The flashing code is listed in the Diagnosing/Troubleshooting plan on page D 24/28-8.

The fault can also be read directly using System Tester 9288. After the repair the fault memory must be erased using the System Tester.

If the fault memory is read via the Check-Engine lamp, repairs may be performed using conventional shop equipment.

The Repair Manual 968, Vol. II, „Transmission", covers manual and Tiptronic transmissions. The description of Tiptronic transmission repairs is found after the section covering the manual transmission.

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