D439E Service Manual 3. Engine Electrical System (D439E)
134
3) Disconnect the battery ground cable.
4) Remove ammeter, voltmeter and tachometer.
5) Connect alternator output wire to "B" terminal of
the alternator.
6) Connect the battery ground cable.
Adjusting Voltage and LRC Function Test,
Trouble-Diagnosis Function Test
This test is to check to see whether the voltage
regulator controls the voltage properly.
1. Preparation
1) Check the battery Installed on the vehicle
whether : it is fully charged.
2) Turn the Ignition switch "OFF".
3) Disconnect the battery ground cable.
4) Connect a digital voltmeter between the ground
cable and “L" or "S" terminal of alternator.
Connect (+) lead wire to "L" or "S" terminal
using special tool “wire-harness connector."
Connect (-) lead wire to proper ground wire or (-
) terminal of the battery.
5) Disconnect alternator output wire from "B"
terminal of the alternator.
6) Connect the DC ammeter (0~150A) In serial
between "B” terminal and the disconnected
output wire.
Connect (-) lead wire of ammeter to the
disconnected output wire.
7) Install engine tachometer. Connect battery
ground cable.
2. Test
1) Turn the Ignition switch "ON” and check to see
whether voltmeter indicates the reference value.
If voltmeter Indicates 0V, it means wire between
"B” terminal of alternator and (+) terminal of
battery is disconnected. Otherwise, it means
fusible link is burned out.
2) Start the engine. Turn the light and all other
accessory switches "ON".
3) Increasing the engine speed up to 2500rpm,
read the voltmeter when alternator output
current drops to 10A.
4) Keep the engine speed at Idle rpm and turn off
the externally applied load (various electric
instruments).
5) Then, apply the externally applied load
momentarily. (load current of 15A or more)
6) Read the voltmeter before the externally
applied load is applied Measure the time taken
until the voltage after the external load is
applied is equal to the voltage before the
external load is applied.
7) In addition charging lamp turns on if "S"
terminal wire is opened with the idle load only. If
the charging lam p does not turn on It means
that voltage regulator is defective.
3. Result
1) If the voltmeter reading agrees with the table of
the adjusting voltage, the voltage regulator is
normally operating. If the voltage value is larger
than the reference value, the voltage regulator
or alternator is defective.
NOTE : Maximum ambient temperature should be
lower than 90℃. (However 100℃ is acceptable
within 10 minutes.)
Ambient temperature of
voltage regulator (℃)
Adjust voltage (V)
20 28~29 V
2) It is normally operating if it is 2~7 seconds to
take until the voltage after the external load is
applied is equal to the voltage before the
external load is applied.
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