P. Running Test Volvo System Tester

P. Running test Volvo System Tester

Sphere of operations
The Running Test registers and stores data about faults. Since the Volvo System Tester stores not only long-term faults but also faults which only appear in the short term, the Volvo System Tester is particularly suitable for use with intermittent faults.




Test description
The System Tester performs tests of signals in a particular sequence and then starts all over again Certain tests are conducted in parallel while other tests requires that the microprocessor works on only one test.

In certain circumstances, different fault messages can be provided for one and the same fault. This is because the System Tester first discovers the secondary fault before measurement of the deviant signal is carried out. One such example is a break in the impulse sensor signal which may provide a variety of different fault messages depending on when the fault occurs.

Several tests require that the System Tester carries out measurements of another value in order to determine whether a fault has arisen or the measured value is normal. As a result, a test may take such a long time that the System Tester cannot complete the entire test procedure before engine speed drops below the relevant lower engine speed limit.




Example, voltage supply from the ignition lock
If voltage drops below 6 V at #35 for Regina, a test is carried out to determine whether voltage is under or over 6 V at #6 before a fault message is stored.

If voltage is below 6 Vat Rex-I the System Tester interprets it as though the ignition has been set at the 0 position and the test is terminated.

If instead the voltage is above 6 at Rex-I the System Tester must wait a while and repeat the Rex-I measurement before a fault measurement at #35 Regina can be stored. This delay is necessary because voltage drops at different rates at #6 Rex-I and #35 Regina when the ignition lock is in the 0-position. If engine speed has dropped below the lower limit during this period, no fault message is stored and the system interprets the situation as though the ignition lock is in the 0-position.

See also End of test, no faults found.




Priority
A fault which arises can generate secondary faults. The System Tester shows the primary fault first and the secondary faults in order of priority.

Since the secondary fault has been generated by the primary fault, only the primary one is to be rectified. This does not apply if one suspects that there are several mutually independent faults in the system. The secondary fault will disappear on its own after the primary one is rectified.

Primary faults which do not generate secondary faults will be shown in the order in which they are discovered.

Order of priority
1. Voltage supply to control unit.
2. Chassis connections to control unit.
3. Sensor signals which affect the engine's basic functions such as engine speed signal.
4. other signals such as idle contact.




Lower engine speed limit
When the signal from the impulse sensor corresponds to a low engine speed, the control units provide no ignition impulses, injection impulses, relay commands etc. and the engine stops.

The RPM limit may vary depending on the state of wear and adjustment of the impulse sensor and carrier plate I flywheel.

The System Tester cannot determine whether signals disappear owing to a fault in the engine or because of something else. The System Tester will show End of test No faults found

Faults which have a lower priority than the engine speed signal will not be stored. However, faults with a higher priority, such as voltage supply will be able to be stored if they are the cause of the stoppage.


Special messages on the display panel

START THE ENGINE OR CRANK 10 SEC.
If the engine does not start, the starter motor must be operated for at least 10 seconds and the ignition key then returned to the 0-position. The reason for this procedure is that the System Tester can then determine whether voltage is being supplied from the ignition lock.

END OF TEST
1. Test completed when the ignition key is turned to the 0-position.
2. Message can also be received if there is a break in voltage supply from the ignition lock on condition that:
^ Voltage supply to Rex-I and Regina disappears simultaneously.
^ Voltage supply to Regina disappears and engine speed drops below the lower limit so quickly that the System Tester does not have time to check the voltage supply to Rex-I. See example voltage supply from ignition lock.

END OF TEST NO FAULTS FOUND
Test completed. The ignition lock was not put in position 0 before the engine speed signal dropped below the lower limit.
Message can be received under the following conditions:
^ When the engine cuts out because of a temporary driving error, such as when the clutch is released too swiftly and the engine jerks to a halt.
^ If the System Tester has not had time to discover the fault before engine speed drops below the lower limit.
^ The fault lies in a part of the ignition or fuel system which is not monitored by the System Tester. e.g fault in the high-voltage section of the ignition system.

Continue the test as follows:
- Press EXIT to exit the Running Test.
- Press ENTER to restart the Running Test.
- Start the engine or operate the starter motor at least 10 seconds.
If the System Tester discovers the fault, a fault message will be produced.