Trionic Engine Management - Fault Diagnosis
CATEGORYEngine
SECTION
2
PAGE
44
ISSUE
08/94-0482
CODE
248
Subject:
Fault Diagnosis: TRIONIC Engine
Management System
Application:
1993- 9000
Many TRIONIC system components which have been replaced are found to be fault-free when subsequently tested. To avoid the unnecessary replacement of good components, follow the diagnostic guidelines in this PSI. To provide further assistance in diagnosis:
^ If malfunctions occur due to defective components, the cause for the failure must be determined by testing the components as described in the relevant fault diagnosis instruction.
^ If the fault is of the intermittent type, it could be difficult to determine the cause. Tests with known good replacement components may then be necessary.
^ If the same fault symptoms occur with the replacement component, the original component must be refitted. For example, changing a control module following complaints about driveability with no previous fault diagnosis is unacceptable.
^ In many cases, trouble is caused by wiring harness faults, corroded cable terminals, pushed out connector pins, etc.
^ File a copy of this PSI in Service Manual 2:7 TRIONIC Engine Management System M1993 (P/N 03 46 924) to aid in future diagnosis.
NOTE:
In several instances In this bulletin we refer you to the 2D M1994- Service Manual 2:7 Engine Management System, Trionic. This is not an error as this manual contains the most current information available at the time of printing of this bulletin.
Cars Affected:
1993- 9000 models with TRIONIC
Suggested Procedure:
A. Fault symptoms such as hesitation during the warm-up phase, uneven running, misfiring, burbling from the exhaust pipe, etc. could be caused by the following:
^ Spark plugs
The wrong type of spark plug or an electrode gap that is incorrect, may result in fault symptoms such as hesitation under partial load, misfiring, burbling when idling, etc. Exhaust burble at higher revs and also at constant engine speed could also occur. An incorrect electrode gap (too wide or too small) affects driveability.
The correct gap is 1.0 (-O.O/+O.1) mm.
^ Crankshaft position sensor
Diagnostic Trouble Code (DTC) P0335 may be generated as a result of low battery voltage if the control module is manufactured before W338. In such cases the DTC should be ignored. This DTC can also be set if the engine stalls with the key in the ON position. Inspect the control module connector pins and sockets (including crimped connection J68). Check operation as described in the Service Manual.
Clear the DTC, lest drive the car and check whether the DTC is generated again.
^ Engine coolant temperature
Check that pins 66, 67 and 68 in the control module connector are not corroded or pushed out.
Also check for pushed out pins and sockets at the sensor connector.
Measure the resistance of the sensor in relation to temperature as described in the Service Manual.
Is the sensor of the correct type? Cars equipped with TCS have a different sensor.
Check the connection between the wiring and the sensor for poor contact and corrosion.
Also check crimped connection J68.
^ Intake air temperature
Check pins 67 and 46 in the control module connector.
Also check for pushed out pins and sockets at the sensor.
^ Manifold absolute pressure sensor
Check first for air leakage in the hose connected to the inlet pipe.
Check the pins at the sensor. The connector must be free from moisture internally and the seal must not be damaged.
Also check that the control module connector pins are not pushed out and are free of corrosion.
Check for correct hose diameter and routing. Check that the hose is connected to correct manifold tap.
Check the sensor as described in the service manual using ISAT and a pressure/vacuum pump.
Clear the DTC, test drive the car and check whether the DTC is generated again.
NOTE:
Slight air leakage could result in problems such as other DTC'S, i.e. adaptation, oxygen sensor.
B. Fault symptoms: DTC'S, driveability problems.
Injectors
The injectors are rarely at fault. However, there is a certain danger of clogging at high mileages or if poor quality fuel is used.
An indication of differences in iinjector flow capacitycan be obtained by looking at the color of the spark plug insulator core nose (see page 142 in M1994- 900 Service Manual 2:7 Engine Management System, Trionic, P/N 03 56 733 ).
Carry out flow capacity measurement as described in the Service Manual. Poor fuel pump capacity and incorrect fuel pressure will affect the flow capacity. In the event of reduced capacity, try using injector cleaner.
Low flow capacity could generate a DTC for adaptation, oxygen sensor.
^ Fuel pressure regulator
Check the fuel pressure as described in the Service Manual.
Check the hose between the air side of the regulator and the intake manifold for damage causing air leakage.
^ Fuel pump
Check flow capacity and fuel pressure as described in the Service Manual.
Incorrect fuel flow/capacity may also be due to a clogged fuel filter or pinched fuel hose.
Low fuel pump capacity may result in poor wide open throttle performance.
Low fuel volume can cause driveability problems at higher engine loads.
^ EVAP canister purge valve
A DTC will be generated only in the event of an electrical fault in the valve.
Check the valve for leakage. Consequential faults, see "Injectors".
Valves with internal leakage may result in a DTC for the oxygen sensor and irregular idling.
Check connectors H6-5, H10-5 and H10-7.
C. Fault symptom: unstable idling in positions other than Park or Neutral.
^ Gear position switch (automatic)
To check, see Service Manual 2:7 for the Saab 9000.
D. Fault symptom: engine will not start or starts and then immediately stops.
Main relay
Connect the test lamp between a good ground and fuse 13. Activate the main relay by means of the ISAT. The test lamp should flash at a frequency of 1 Hz.
^ Fuel pump relay
Connect the test lamp between a good ground and fuse 14. Activate the fuel pump relay by means of the ISAT. The test lamp should flash at a frequency of 1 Hz.
E. Fault symptoms: large idling fluctuations, poor or no AC operation.
^ A/C relay
Activate the relay using ISAT. Refer to the Service Manual.
F. Fault symptoms: reduced charge pressure in all gears, rpm drops on declutching when changing gear.
^ Road Speed signal
A speed signal fault should generate a DTC.
Refer to the Service Manual for correct procedures.
G. Fault symptoms: idling speed too low when engine cold and/or too high when engine hot.
^ Idle air control valve (non-TCS cars)
Hunting engine speed. May stall on decel or at AC cut in.
No compensation for increased load such as high electrical consumption, AC turn on, etc.
^ Throttle position sensor (non-TCS cars)
If a DTC is generated for the throttle position sensor in an ETS car, the fault is in the ETS system and not the TRIONIC system.
See fault diagnosis in Service Manual 2:5 for the Saab 9000. See PSI 11/92-0271 (Sec. 2, p. 23).
Cars without ETS, see fault diagnosis for the idle air control valve in Service Manual 2:7 TRIONIC for the M94 Saab 900.
H. Fault symptoms: misfiring, uneven running, charge pressure too low and synchronizing faults.
^ Ignition discharge module
Misfiring or no start, particularly when the engine is hot. Also may stall or experience no start condition when engine is hot, restarts when cool.
Always check the spark plugs and adjust the gap to 1.0 -0.0/+0.1 mm before pinpointing the ignition discharge module as the cause of the fault.
Fault diagnosis as described in Service Manual 2:7 TRIONIC for the Saab 900 and PSI 01/94-0422 (Sec. 3, p. 66).
Charge pressure too low, ignition discharge module may transmit incorrect knocking level. Use ISAT Command Code EE41. Knock level should be low at idle (ISAT display 8-20).
I. Fault symptoms: low/high charge pressure
^ Charge pressure control valve
Check for blockage in the valve control hoses (oil coating that can cause sticking/binding/cracking of the valve disc) or an electrical fault.
Both mechanical and electrical failures may occur. Use ISAT Command Code 3020 or 3120. If the valve does not activate, there is an electrical fault. Check the valve windings and wiring.
A connection on one of the coils may have come loose from the pin inside the valve with the result that control of charge pressure is lost. This may also cause a short circuit which causes burnout of the control module's output stage.
To check the operation of the charge pressure control valve, see page 149 in Service Manual 2:7 TRIONIC for the M94 Saab 900.
If the control module's output stage has burnt out and therefore needs to be changed, a check should first be made to ascertain whether the control valve's windings are short circuited or not. Otherwise this will cause the burn out of the control module's output stage again. Refer again to the Service Manual.
A mechanical fault can occur if the floating metal disc becomes permanently attached to one of the solenoids, or it may become stuck in the valve housing. The ISAT Command Code may still activate the valve (buzzing noise). However, the valve could still be defective.
^ Control module
J. Unplug the control module connector and check for pushed out pins and sockets. Spray pins and sockets with a little "Kontact 61". Plug in the control module again and carry out adaptation.
K. Connector sockets 66, 67 or 68 have pushed out and caused intermittent and/or permanent faults. The same problem has also occurred in crimp connection J67.
Just changing the control module on account of driveability problems without first performing fault diagnosis when a fault has been found to exist is absolutely wrong.
Find out exactly what driveability problems the previous control modules could cause. Specify them accurately so that unnecessary replacement of control modules is avoided.
Oxygen sensor
A DTC for the oxygen sensor is seldom caused by a fault in the sensor itself but rather as the result of incorrect fuel-air mixture for some other reason. Refer to the Service Manual for proper test procedures.
Corrosion between the threads on the sensor and exhaust pipe can cause a DTC.
IMPORTANT
Do not use contact spray or grease on the oxygen sensor's connector.
Fault Diagnosis Schedule, M93- Saab 9000
This fault diagnosis schedule (fault symptom/probable cause) should be regarded as a guide or aid when diagnosing a fault.
1. Check the following fuses:
23 (+30 power supply to control module, FA23 22 A)
13 (+15 power supply to control module, FA13 22 A), several components are supplied via fuse 13
14 (power supply from fuel pump relay to fuel pump, A 14 22A).
2. Ignition switch in ON position.
Check whether the CHECK ENGINE lamp (MIL) lights up and stays on for about 3 seconds. Also check the fuel level.
^ if the CHECK ENGINE lamp (MIL) does not light up, the control module is not connected to the + 15 power supply. if the CHECK ENGINE lamp (MIL) lights up weakly or flashes, the control module is not connected to ground or the +30 power supply.
3. The main relay supplies power to the injectors and ignition discharge module. Therefore, check the operation of the main relay as follows:
^ connect the test lamp to the connector of the idle air control valve
^ turn the ignition switch to the OFF position remove fuse 23 for 5 seconds
^ put fuse 23 back in again
^ turn the ignition switch to the ON position. Check whether the test lamp lights up for about 6 seconds and then goes out. It it does not, see "Fault diagnosis. main relay".
^ when the test lamp goes out, run the starter motor. This should cause the test lamp to light up again. If it does not, the control module is receiving no information from the crankshaft position sensor. See "Fault diagnosis, crankshaft position sensor.
4. The fuel pump relay supplies the fuel pump with power. Therefore, check the operation of the fuel pump relay as follows:
^ turn the ignition switch to the OFF position. Remove fuse 23 for 5 seconds.
^ put fuse 23 back again
^ turn the ignition to the ON position. Listen to check whether the fuel pump is working. The fuel pump should run for about 2 seconds. If it does not, see "Fault diagnosis, fuel pump relay.
5. Check the following:
^ as described in point 3, check that the ignition discharge module and injectors are supplied with power from the main relay. It this is not the case, carry out fault diagnosis on the leads to the injectors, J37, J67, and H24-1. Ignition discharge module H10-7.
^ check that the ignition discharge module produces spark. If it does not, see Service Manual 2:3 Fuel system and air induction system.