Trionic T8 Fuel Control System: Diagnosis Saab 9-3 II

Fault diagnosis strategy for electronic systems

1. The customer's description of the problem constitutes a basis for the fault diagnosis strategy. If necessary, the customer must demonstrate the trouble on the car to avoid misunderstandings.
2. In certain cases, the function may be correct. Good product knowledge is required to decide this. If the function is correct, this must be explained to the customer.
3. If the function is judged to be faulty, the car should be repaired. Saab's fault diagnosis strategy assumes that the technician is familiar with the customer's description of the problem. So note the customer's complaint and any other observations on the job sheet.
4. The technician obtains a readout of the diagnostic trouble codes from all systems. A malfunction in one system can often be caused by a fault in another system.
5. The car may contain diagnostic trouble codes which are secondary faults or which have been incorrectly generated. Compare the customer complaint with the symptom description for the various diagnostic trouble codes. WIS has a quick search function for this purpose. If the symptom description for a diagnostic trouble code matches the customer's complaint, this diagnostic trouble code is probably caused by the primary fault. Repair as per instructions.
6. If there is no match with diagnostic trouble codes or symptoms, the technician must diagnose the fault himself. Search in WIS under fault diagnosis for symptoms in the system where the fault exists. Also check whether there is a TSB/MI in force. If the symptom description in the current system matches the complaint, the right fault diagnosis description has probably been found. Repair as per instructions.
7. Certain fault symptoms can be remedied by reprogramming the control module. Does the customer complaint stem from a known software problem in a programmable control module? Reprogram the control module following the instructions in SPS.
8. If there is no match with diagnostic trouble codes or symptoms, the technician must diagnose the fault himself. Good technical product knowledge is required to solve this type of problem.
9. A final check must be carried out after the repair.
10. The car is ready.

Diagnostic tool

The software has been subdivided. For Saab 900 and 9000 (version 44.000 and later) a 10 Mbyte memory card is used. For 9-5, 9-3, 9-3 Sport Saloon and SPS (version 102.000) a 32 Mbyte memory card is required. The subdivision gives assured functionality for systems in older cars and less validation work with new releases. Both cards can sit in the diagnostic tool. You switch between cards by starting the diagnostic tool, waiting until the introduction screen is shown and then pressing

1. Shift
2. Left arrow or right arrow
3. Shift

For 9-3 Sport Saloon (9440), connect the P-bus and I-bus are directly connected to the data link connector, which requires use of an adapter (CANdi) for the diagnostic tool. The increased complexity of the car has increased the demands on the diagnostic tool. The diagnostic tool has therefore been adapted more directly to various user situations. When Tech 2 is used for car models other than the 9-3 Sport Saloon and 9-5 prior to MY06, the CANdi box must not be used.

Diagnostic Strategy

The diagnostic strategy remains unchanged. You first read the diagnostic trouble codes from all the control modules and then perform fault diagnosis on the diagnostic trouble codes whose symptom description corresponds with the customer complaint. The difference in the diagnostic tool is that you now always read the diagnostic trouble codes from all control modules one at a time. You can then choose to transfer the diagnostic trouble codes to WIS via an RS 232 cable or enter them by hand. The diagnostic trouble codes now have two extra characters to point out the type of fault more accurately.

To easily find the activations or read values used in fault diagnosis for a specific trouble code you can select, "Diagnostic Data, trouble code" and then see directly just the values used in WIS fault diagnosis.

Fault diagnosis by symptom

Using fault diagnosis by symptom is more difficult to determine in advance which control module should be contacted to read values or activate. Accordingly the diagnostic tool has been divided into operations. You no longer contact a control module but an operation, that is a virtual control module. This means that with a fault on e.g. the left flashers you do not need to think about which control module is involved in the operation, you just select "Left flashers" from the menu. The diagnostic tool will then present the values and activations from all control modules involved in the left flashers operation. If you find something wrong, you can then see which control module the value came from and then perform fault diagnosis using, e.g. the wiring diagram.

During fault diagnosis on a specific operation using the diagnostic tool information about this can be found in WIS. In WIS there is an extra search window that uses the same navigation as on the diagnostic tool.

On Board Diagnostics

1. The job of diagnostics is to detect faults and store them so that they can later be read off using the diagnostic tool.
2. Diagnostic trouble codes are the result of the fact that much of the software in modern control modules is constantly looking for faults. In an engine management system, for example, more than 50% of the program code nowadays is used entirely for diagnostics.
3. ISO/SAE has specified what diagnostic trouble codes should look like, which is a legal requirement in the USA. ISO/SAE determines all codes which have 0 in the second position.

Examples of diagnostic trouble codes

1. P0107 Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
2. P0303 Cylinder 3 Misfire Detected
3. P0601 Internal Control Module Memory Check Sum Error
4. P0705 Transmission Range Sensor Circuit Malfunction (PRNDL Input)

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The following are monitored

1. Internal control module faults
2. Analog inputs
3. Digital inputs
4. Outputs

To bear in mind in respect of On Board Diagnostics

1. Not all faults that arise can be identified. Even if there is no electronic fault for an injector, it does not necessarily mean that it is injecting petrol as it is supposed to. It only indicates that the circuit is OK.
2. In general, digital inputs have no or poor diagnostics. Use the diagnostic tool to check the read values.
3. In general, analog inputs have good diagnostics. One knows that the circuit is OK if no diagnostic trouble code is set. One cannot, however, be sure that the value is correct. The fact that no diagnostic trouble code is set can be misleading. Use the diagnostic tool to check the read values.
4. Outputs generally have good diagnostics. You can be fairly certain that the circuit is unbroken if no diagnostic trouble code is set, but despite this you cannot know whether the device is doing its job. Use the diagnostic tool to activate it and check that it is working.

Relays are sometimes involved. The control module is only able to check that everything is OK in its own circuit, i.e. via the relay winding. This tells you nothing about how the fuel pump or radiator fan is working.

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1. When detaching connectors with locks, it is essential that the lock is released before the connector is detached. Ensure the connector locks properly when connecting. Example of some different connector types used in the car: Pull out the slide to unlock the connector. After attaching the connector lock it by pressing in the slide. NOTE: Using a small screwdriver will help to unlock the connector. Press in the lock tab to unlock the connector. Make sure the connector is locked properly when connecting. Pull out the slide to unlock the connector. After attaching the connector lock it by pressing in the slide. Press in the brace catch and push forward the brace. Push back the brace to lock the connector after connecting. NOTE: Make sure the brace is locked in the right position to ensure good contact between connectors. Lift up the lock tab to unlock the connector. Make sure the connector is locked properly when connecting. Press in the connector lock tab to release the brace. Release the connector slide while pushing the brace forward. NOTE: The connector may be damaged if too much force is used to push forward the brace without first releasing the slide. Push back the brace to lock the connector after connecting.
2. Ground yourself by touching the car body/engine before removing or fitting any of the connectors on the car's control modules.
3. Never pull the wiring harness when removing a connector.
4. Never touch the pins on the control module with your hands or clothes. IMPORTANT: Incorrect handing or the use of the wrong tool can damage the sleeves in the connector. Use a test cable (part no. 86 12 731) of the correct size to avoid damaging the sleeves in the connector.
5. When testing only probe tips intended for the purpose are to be used to avoid damaging the contacts. Use a test cable (part no. 86 12 731) of the right size.
6. Connectors may only be repaired when using specified special tools and spare parts.
7. The following connectors must not be repaired: Screened wires/coaxial cables (e.g. ESP sensor cable) Airbag system and pyrotechnical seat-belt tensioner system High tension cable (e.g. ignition system, xenon lamp).

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1. Check for any contact problems in connections.
2. Check contacts, connectors and crimp connections with respect to oxidation, loose pins and pin clamping force. IMPORTANT: Incorrect handing or the use of the wrong tool can damage the sleeves in the connector. Use a test cable (part no. 86 12 731) of the correct size to avoid damaging the sleeves in the connector.
3. To check the connector clamping force, use a test cable with the right pin size (from kit 86 12 731). NOTE: Using a test cable that is too big will damage connector sleeves. Insert the test cable pin into the connector pin to feel the clamping force of the pins in question. Poor clamping force of the connector pins can cause bad contact. Also check that the engagement height of the pin is the same as the other pins in the connector. An engagement height that is too low could be an indication of a loose pin in the connector, which could cause bad contact.
4. Check wires and connections for open circuits.
5. Check wiring harness, connectors and ground connections.

Fault symptom

1. Poor driveability
2. Impaired performance
3. Engine has uneven or low idling speed
4. Surge or hesitation upon acceleration

Diagnostic trouble code P0606 00 is indicated

Diagnostic help

The erroneous generating of the diagnostic trouble code is due to the software and applies only to cars equipped with automatic transmission. ECM for T8 must not be replaced.

Too slow reaction on the absolute pressure sensor or pressure too high in the intake manifold (air leakage)

If P0106 is indicated and a faulty component cannot be detected via normal fault diagnosis then this can be due to incorrect camshaft setting. In this case the leak will come from the intake valves as they are not closing at the right moment. Consequently air is forced back by the pistons in the intake manifold and causes a too slow reduction in pressure.

DTCs P0442, P0455 or P0456 indicated

Faulty function of Check Engine lamp.

During normal function, the Check Engine lamp should light until the engine starts.

Fault diagnosis procedure is not available.

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Engine does not start.

During operational cycles under 5 minutes, the vehicle may seem hard to start. This may be due to a clogged spark plug.

Most functions that can make the engine inoperable are monitored by self-diagnostics and therefore generate DTCs if they are faulty.

Fault diagnosis is only used for faults that are not monitored by self-diagnostics.

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No starter motor cranking.

Engine does not start.

Check battery cable connections, to the battery and to the chassis, are tightened and have good contact without oxide or corrosion.

Most functions that can prevent starter motor cranking are monitored by self-diagnostics and therefore generate DTCs if they are faulty.

Fault diagnosis is only used for faults that are not monitored by self-diagnostics.

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