Part 2
OBD (II)INTRODUCTION - Continued
Fault erasing counter
For each recognised fault, an individual fault erasing counter is kept. It contains the defined number of required OK tests until the respective fault is erased in the fault memory.
The first time a fault is recognised, the fault erasing counter is set to 80, for example (suspected fault).
If an unshedded fault is recognised as healed, the fault erasing counter is set to 10 (only visible for the PST2). (Workshop help for very sporadic faults)
Each time a shedded fault is recognised (= CE light on), the fault erasing counter is set to 40, for example. It retains this value until fault healing is recognised.
The fault erasing counter is decreased by 1 after each warm-up cycle if the fault in question is recognised as unshedded or healed. When the fault erasing counter reaches the value 0, the fault is erased from the memory. Faults that are confirmed but not recognised as healed are not decremented in the fault erasing counter.
Fault frequency counter
This indicates how often a fault has recurred after its first occurrence. If the value is "1", the fault has occurred only once. Thus, it can now be "present" or "not present". The number in the fault frequency counter is increased by 1 whenever the fault status changes from "not present" to "present". A large value in the fault frequency counter thus might indicate a loose contact. It is important to remember that the ambient conditions stored in the "extended fault memory" relate only to the first and last occurrence of the fault.
WARNINGS
DANGER:
- Danger of accident it test and diagnostic equipment (PST2, scan tool, etc.) is operated while driving.
- Always get a second person to operate the test and diagnostic equipment while driving
- Some tests or system checks can affect vehicle handling so make sure to carry out these tests in a cordoned-off area.
DANGER:
- Gasoline is toxic.
- Inhaling vapours can lead to irritation of the mucous membranes and eyes
- It represents a serious risk to health when inhaled, touched or swallowed over extended periods
- Wear a breathing mask with active charcoal filter; do not breathe in any fuel vapours
- Wear protective gloves that are fuel-resistant
- Perform work on the fuel system only in well-ventilated rooms
- Relieve the fuel pressure before opening the fuel lines or fuel hoses
- Collect escaping fuel; absorb it if necessary with a suitable binding material and dispose of properly (special-category waste.)
- Pay attention to cleanliness when working on the fuel system
DANGER:
- Working with gasoline involves a danger of fire and explosion
- Keep away from sources of ignition
- Do not smoke
- Danger of fire due to naked flames and sparks, e.g. during welding or grinding work
- Danger of fire due to escaping fuel, e.g. on hot engine components and/or due to electrostatic charging
- Secure the vehicle, e.g. with a warning sign
- Change any clothing soaked with fuel immediately
- In case of fire, use a C02 or dry powder fire extinguisher
WARNING:
- Danger of injury by hot and/or rotating parts.
- Do not perform any work on the engine and/or exhaust system when the engine is running and/or hot.
- Danger of injury due to fan start-up. Fans can start up unexpectedly when the ignition is switched on, when control module connector B is disconnected, when the air-conditioning system is switched on or when the engine is warm. Make sure to wear sate, correctly fitting clothes and any necessary personal safety gear (hair net). Do not work in this area when the engine is running.
CAUTION:
Risk of property damage if batteries and plug connectors of the control modules are handled incorrectly.
- Never disconnect the battery terminals with the engine running.
- Never start the engine without the battery terminals properly connected.
- Never connect or disconnect the plug connections of the control modules or other electronic components with the ignition switched on.
- Please observe warnings in the Body Manual if you intend to do welding work on vehicles.
Notes on troubleshooting
Working on oxygen sensors
NOTE:
Oxygen sensors used for DME 7.1.1
The LSU (universal oxygen sensor) can determine the oxygen value in a wide range.
The LSF (flat oxygen sensor) can only determine oxygen values greater or less than 1 (the rich-lean jump).
Oxygen sensor ahead of catalytic converter (LSU) has a 6- pole connector
Oxygen sensor after catalytic converter (LSF) has a 4-pole connector
NOTE:
Do not confuse oxygen sensor ahead of catalytic converter and oxygen sensor after catalytic converter as this Will cause implausible fault entries. This note refers to the possibility of mistakenly installing a sensor intended for installation in front of the catalytic converter at the installation position for the sensor behind the catalytic converter in the exhaust system. The plugs themselves are coded and cannot be swapped.
NOTE:
Do not use contact spray on the oxygen sensor plug connections as this may cause irreparable damage to the wiring (contamination of the oxygen sensor via the reference air channel).
Troubleshooting procedure
Troubleshooting is possible only if the fault is actually present. This means: targeted troubleshooting according to instructions (diagnosis/troubleshooting for the individual DTCs) is only possible if the entry has the status 'present' in the fault memory.
If the fault is 'not present' at the moment, it is necessary to check the following:
- Has the fault healing counter and possibly the fault erasing counter been decremented? This would indicate that the fault has been corrected
- Did the fault occur a long time ago? Read out the extended fault memory (operating time and mileage for last fault entry)
- Are the diagnostic conditions fulfilled? Carry out a short test or test drive, if necessary
- Are all the plug connections and ground points of the current path in question OK?
- By pulling and shaking, put all wiring harnesses of the current path in question in a state corresponding to that of driving operation (loose contact).
- Condition/leak tightness of the catalytic converter
- For tank system: Condition/leak tightness of hoses and possibly the tank cap
Diagnosis conditions
NOTE: Important. Switch off all unneeded loads before starting diagnosis. When working with the ignition switched on, connect a suitable battery charger to the vehicle battery or to the jump lead starting terminals intended for this purpose.
NOTE:
Only if the preconditions listed under 'Diagnostic conditions' have been met is/was it possible for the control module to recognise the fault For this reason, it is necessary to comply with the specified procedure after remedying a fault:
1. Erase fault memory once you have printed or stored it
2. Meet the prerequisites listed under 'Diagnostic conditions' or carry out a short test with the 9588 Porsche System Tester II. It is important to remember here that faults can only be detected with the DME control module based on reset adaptation values (particularly for fuel supply and misfire detection) after driving the vehicle for a long time. It may be possible to observe the relevant adaptation values ("actual values") during a subsequent road test in order to pinpoint a particular tendency.
3. Read out the fault memory again.
Possible fault causes
NOTE: This is where the 'Possible fault causes' leading to the fault are listed Please bear in mind that additional faults may be stored in the memory after troubleshooting under certain circumstances (e.g if plug connections are disconnected). After repairing the vehicle, read out the fault memories of all control modules and erase all faults that were added during troubleshooting or repairs.
Faulty DME
NOTE:
- Faulty control modules are extremely rare. Although almost every fault can theoretically also be caused by a faulty control module, past experience has shown that, for DME control modules in particular, even control modules sent in for inspection turned out to be OK.
- We would again like to stress the necessity of thoroughly examining all other possible fault causes before replacing a DME control module (this is the last logical step at the end of a fruitless troubleshooting procedure). If necessary, the fault entry must be deleted and a test drive or short test must be performed.
- If further faults have been recorded, these are to be remedied first according to instructions (example: a fault in the inlet camshaft can, under certain circumstances, cause an oxygen sensor fault to be issued).
- CAN Timeout fault entries are critical faults which, when they occur alone, are not necessarily caused by a malfunction Instead, these CAN Timeout faults are intended to provide additional information when other faults (even 'non-CAN faults') are recorded or when functions are impaired.
- Fault entries that are connected only with troubleshooting, repairs or the programming of control modules (e.g CAN Timeout errors) must be erased.
Diagnosis/troubleshooting
NOTE:
It is possible to access the 'extended fault memory' with the aid of the fault memory info key [F8] on the 9588 Porsche System Tester II. In addition to the freeze frames and ambient conditions, the extended fault memory also contains information about the type of fault.
Fault type
The following fault types are possible for DME:
- Signal implausible (fault type 1, Plaus)
- No signal/communication (fault type 2, Sig)
- Below lower limit (fault type 3, Min)
- Above upper limit (fault type 4, Max)
Several faults can also be stored at the same time.
Fault status
The following status types are possible:
- Present
- Not present
This information should be saved and printed with the Save key [F4].
NOTE:
- Faults not present: If faults are entered but not present at the moment, it is necessary, depending on the system, to check the parts of the wiring connected to moving parts on and in the vehicle once the diagnostic conditions have been met or set. Various switching states that can cause a fault to occur must be simulated using the circuit diagram. Bear in mind that the 9588 Porsche System Tester II can show the current fault status only to a certain extent. Here, the fault frequency counter shows the operating time and mileage for the last occurrence of the fault.
- In difficult cases involving faults that are not currently present, it is a good idea to erase the fault memory (after printing it out) and check whether the fault is recorded again when a loose contact is simulated.
NOTE:
- Visual inspection of plug connections: As part of troubleshooting, it is important to ensure that the pins in the affected plug connections are neither damaged nor corroded, both on the component side and on the wiring-harness side. Furthermore, the wiring and the connectors must be checked for signs of external damage (cracks, etc.) and proper contact (pins not bent, spread apart or pressed into the housing) Repair damaged or corroded pins if possible, otherwise replace them. Repair or replace damage wiring. If wiring on the oxygen sensors is damaged, always replace the entire oxygen sensor.
- Visual inspection of components: As part of troubleshooting, it is important to ensure that the affected components or wiring harnesses show no visible signs of damage (e.g. cracks, deformation or chafing marks). This is particularly important for components that cannot be tested with a multimeter, e.g. the ignition bar modules, or components that can cause sporadic faults due to penetrating moisture.
NOTE:
Battery positive voltage and signals: The general precondition for diagnosis/troubleshooting is a battery positive voltage in the range from 11.4 V to 14.5 V. This must be checked and ensured if necessary using a suitable battery charging device.
NOTE:
Unless stated differently, specified resistance values refer to an ambient temperature of 20 °C.
End of troubleshooting (--> End)
--> End identifies the end of the diagnosis/troubleshooting procedure described in the troubleshooting tables. The procedure for the repair is contained in the respective repair instructions for the corresponding repair group. Once the repair has been completed, erase the DME control module fault memory, adapt the throttle adjusting unit if necessary and subsequently perform a short test or test drive to achieve the diagnostic conditions for the relevant fault. Then read out the fault memory again. The Ready statuses must be produced, depending on the country.