Diagnosis Start Here

To assess a Tiptronic transmission for which complaints have been received, the information about the fault and the fault occurrence should be as complete as possible.

To avoid extra damage during test drives or faulty diagnosis results, the following items must be checked and corrected (if required) prior to the test drive:

1. Read out fault memory with System Tester 9288 and correct fault.
Check to make sure that battery, connectors, ground points O.K.

2. External damage, leaks at transmission (ATF leaks) or final drive (hypoid oil loss), disconnected cables.

3. ATF level in transmission correct, fluid is neither dirty nor does it leave a burning smell. If ATF is dirty or if it leaves a burning smell, it is recommended to replace the Tiptronic transmission if complete removal of the dirt residues cannot be ensured. In addition, the coolant lines and the cooler must be flushed.

4. Engine operation, full opening of throttle when accelerator is in full-throttle position

NOTE:
- If a system fault occurs, the Tiptronic system shifts into a reduced driving program. The warning lamp comes on and the automatic system shifts to 4th gear, irrespective of the selector lever position.

- If the vehicle is started again in the "P" or "N" selector lever position after it has been stopped, only 3rd gear is activated in the "D", 3, 2 or 1 selector lever positions.

CAUTION:
- The reverse gear interlock monitor is inoperative.
- Do not shift into "R" while the vehicle is in motion.
- Do not run resistance measurements on live wiring.
- Before replacing the transmission or the electronic control unit, always check the wiring harness and system components with the System Tester, otherwise the new control unit or transmission may be destroyed again.

The Test Drive
The test drive should be used to check if the customer complaint situations actually occur when the vehicle is driven. It is actually preferable to have the customer drive the car and to check for any potential faults, malfunctions or even for incorrect operation by the driver.

Check all functions of the transmission during the test drive:
- All shifts, including in kickdown position in the automatic gate, as well as shifts in the manual gate
- Various driving speeds
- Driving in reverse (uphill if possible)
- Stall speed

A safe diagnosis is only possible if you are familiar with the design and operation of the Tiptronic transmission. Read the Functional Description brochure carefully: Porsche Tiptronic WKD 496 620.

Make your diagnosis using the "Troubleshooting the Tiptronic transmission" section and determine the type of repair required.

This diagnosis plan is based on the fault memory contents. If no fault is stored although a malfunction is present, the troubleshooting plan for the mechanical/hydraulic section should be used.

Troubleshooting requires that the person performing the tests:
^ is familiar with the location of components, operation and technical relationships of the systems being tested (refer to Model Information)
^ is able to read and evaluate Porsche wiring diagrams
^ knows the functions of circuits and relays
^ is capable of using testers such as oscilloscope, voltmeter, ohmmeter and ammeter, as well as of evaluating the test results.


NOTE:
- The fault text displayed (fault list in case of flashing code) does not necessarily indicate a defect in this component, but may also refer to a fault in the corresponding control unit and the wiring (paths) between the component and the control unit.
- Before reading out the fault memory, do not try to locate faults by disconnecting plugs etc. while the engine is running as this may be stored as a fault in the fault memory.

Notes for System Tester 9288

If the tester display shows Fault not present, this may indicate:
^ Fault did not exist at the time of testing (e.g. in the case of loose connections) Remedy: Visual inspection of path
^ The conditions under which the fault is tested do not correspond to the conditions under which the fault occurred. Remedy: Conform with the conditions displayed on the tester
^ Signal unplausible: The signal of the monitored component is not within the tolerance range of the value preset in the control unit.

Signals that can be checked with the oscilloscope
^ Speed signal (from ABS)
^ Speed signal (from transmission)
^ Rpm signal (n-Mot) (from DME)
^ ti signal (load of DME)