|
|
ENGINE ELECTRICAL - Charging System 16-7 REGULATED VOLTAGE TEST B Blue Red Ignition switch Load FR L S G MB991519 Alternator Battery Voltmeter Ammeter Yellow Engine-ECU Black This test determines whether the voltage regulator is correctly controlling the alternator output voltage. (1) Always be sure to check the following before the test. Alternator installation D Check that the battery installed in the vehicle is fully charged. (Refer to GROUP 54 - Battery.) D Alternator drive belt tension (Refer to GROUP 11 - On-vehicle Service.) D Fusible link D Abnormal noise from the alternator while the engine is running (2) Turn the ignition switch to the “LOCK” (OFF) position. (3) Disconnect the negative battery cable. (4) Use the special tool (Alternator test harness: MB991519) to connect a digital voltmeter between the alternator S terminal and earth. (Connect the (+) lead of the voltmeter to the “S” terminal, and then connect the (−) lead of the voltmeter to a secure earth or to the battery (−) terminal.) (5) Disconnect the alternator output wire from the alternator “B” terminal. (6) Connect a DC test ammeter with a range of 0 - 100 A in series between the “B” terminal and the disconnected output wire. (Connect the (+) lead of the ammeter to the “B” terminal. Connect the (-) lead of the ammeter to the disconnected output wire.) (7) Reconnect the negative battery cable. (8) Connect a tachometer or the MUT-II. (Refer to GROUP 11 - On-vehicle Service.) (9) Turn the ignition switch to the ON position and check that the reading on the voltmeter is equal to the battery voltage. If the voltage is 0 V, the cause is probably an open circuit in the wire or fusible link between the alternator “S” terminal and the battery (+) terminal. (10)Turn all lamps and accessories off. (11)Start the engine. (12)Increase the engine speed to 2,500 r/min. (13)Read the value displayed on the voltmeter when the alternator output current alternator becomes 10 A or less. |