Alternator: Testing and Inspection
Quick test of alternator function
Information
The function for quick testing the alternator differs depending on whether the vehicle has the automatic start/stop of engine function or not.
That the vehicle has the automatic start/stop of engine function can be identified by the Drive button (switch) located in the tunnel console.
Select one of the following functions:
1. Vehicles with the function automatic start/stop of engine.
2. Other vehicles.
1 - Quick test of alternator function
2 - Quick test information
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Quick test information
Note! Does not apply to vehicles with the function automatic start/stop of engine.
The central electronic module (CEM) has built-in functions for regulating the alternator (alternator control module (ACM)).
To charge the battery optimally, output voltage from the alternator is calculated based on the calculated battery temperature. The central electronic module (CEM) calculates battery temperature from outside temperature, which is obtained from the outside temperature sensor.
Depending on the vehicle's ambient temperature and/or if the vehicle has been without power, the calculated battery temperature (read temperature) may differ slightly from the battery's actual temperature for up to 24 hours afterwards.
In the following tests, battery temperature in the central electronic module (CEM) is changed, thereby changing voltage from the alternator.
The test is divided into two parts - an automatic test and a manual test.
Select one of the alternatives below:
1. Automatic test of alternator function.
2. Manual test of alternator function.
1 - Automatic test of alternator function
2 - Manual test of alternator function
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Automatic test of alternator function
- Start the engine and allow it to idle for approx. 1 minute.
- Make sure that no extra electrical consumers are connected. Turn off functions that consume a great deal of power, such as the ventilation fan, heated rear window/door mirrors, heated seats, lighting, radio system, etc.
Start the automatic test by clicking the Start button.
Values for battery temperature and voltage are read and displayed continually during the test. A number of tests are performed in which various battery temperatures are used from -30 °C to +90 °C. Between each battery temperature change, there is a delay of approx. 10 seconds before the voltage is read. This allows the alternator to have time to set the right voltage in relation to the set battery temperature.
The entire test takes approx. 2 minutes and a message is displayed when the test is complete. Compare the values reported in the readings for battery temperature (T) and voltage (U) with the values in the table.
If the voltage values generally lie below the lower limit (low voltage), redo the test at an engine speed of 2500 rpm.
If the voltage is within the tolerances this time, alternator function is OK, but the test indicates that the battery is not fully charged. If voltage still deviates, there is a fault in the charging system.
Note! The read-out voltage is read internally from the central electronic module (CEM) and deviates slightly from the actual alternator output voltage due to a drop in voltage in the wiring harness.
Continue - DONE
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Manual test of alternator function
- Start the engine and allow it to idle for approx. 1 minute.
- Make sure that no extra electrical consumers are connected. Turn off functions that consume a great deal of power, such as the ventilation fan, heated rear window/door mirrors, heated seats, lighting, radio system, etc.
Values for battery temperature and voltage are read and displayed continually during the test. Select values that are available in the list window. Wait approx. 5 seconds between each battery temperature change to allow the alternator to have time to set the right voltage in relation to the set battery temperature. Then read battery temperature and voltage between each temperature selection.
Compare the values from the readout of battery temperature and voltage with the values in the table.
If the voltage values generally lie below the lower limit (low voltage), redo the test at an engine speed of 2500 rpm.
If the voltage is within the tolerances this time, alternator function is OK, but the test indicates that the battery is not fully charged. If voltage still deviates, there is a fault in the charging system.
Note! The read-out voltage is read internally from the central electronic module (CEM) and deviates slightly from the actual alternator output voltage due to a drop in voltage in the wiring harness.
Continue - DONE
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Quick test of alternator function
Quick test information
The Engine control module (ECM) has built-in functions for regulating the alternator (alternator control module (ACM)).
To charge the battery optimally, the output voltage from the alternator is calculated from the battery's calculated temperature. The Engine control module (ECM) receives the battery temperature from the battery monitoring sensor.
Depending on the vehicle's ambient temperature and/or if the vehicle has been without power, the calculated battery temperature (read temperature) may differ slightly from the battery's actual temperature for up to 24 hours afterwards.
In the following tests, battery temperature in the Engine control module (ECM) is changed, thereby changing voltage from the alternator.
The test is divided into two parts - an automatic test and a manual test.
Select one of the alternatives below:
1. Automatic test of alternator function.
2. Manual test of alternator function.
1 - Automatic test of alternator function
2 - Manual test of alternator function
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Automatic test of alternator function
- Start the engine and allow it to idle for approx. 1 minute.
- Make sure that no extra electrical consumers are connected. Turn off functions that consume a great deal of power, such as the ventilation fan, heated rear window/door mirrors, heated seats, lighting, radio system, etc.
Start the automatic test by clicking the Start button.
The values for battery temperature and voltage can be readout and shown continuously during the actual test. A number of tests are performed where different battery temperatures are used, from -20 °C till +60 °C. Between each battery temperature change, there is a delay of about 10 seconds before the voltage is read off. This is so that the alternator has time to set the correct voltage in relation to the set battery temperature.
The entire test takes about 1.5 minutes and a message appears stating when the test is complete. Compare the values from the readout of battery temperature (T) and voltage (U) with the values in the table.
If the voltage values generally lie below the lower limit (low voltage), redo the test at an engine speed of 2500 rpm.
If the voltage is within the tolerances this time, alternator function is OK, but the test indicates that the battery is not fully charged. If voltage still deviates, there is a fault in the charging system.
Note! The read out voltage is read from the battery monitoring sensor via the Engine control module (ECM).
Continue - DONE
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Manual test of alternator function
- Start the engine and allow it to idle for approx. 1 minute.
- Make sure that no extra electrical consumers are connected. Turn off functions that consume a great deal of power, such as the ventilation fan, heated rear window/door mirrors, heated seats, lighting, radio system, etc.
The values for the battery temperature and voltage are read and shown continuously. Select the optional values from the drop down box. Wait about 10 seconds between each battery temperature change. This is so that the alternator has time to set the correct voltage in relation to the set battery temperature. The read off the battery temperature and voltage between each temperature selection.
Compare the values from the readout of battery temperature and voltage with the values in the table.
If the voltage values generally lie below the lower limit (low voltage), redo the test at an engine speed of 2500 rpm.
If the voltage is within the tolerances this time, alternator function is OK, but the test indicates that the battery is not fully charged. If voltage still deviates, there is a fault in the charging system.
Note! The read out voltage is read from the battery monitoring sensor via the Engine control module (ECM).
Continue - DONE
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