12
13
4
ALTERNATOR OVERVIEW
This test measures the output of the alternator under load conditions.
This information provides the basis for further charging system tests. It
also detects the presence of an open or shorted diode that causes an
output loss of several amps and can cause the failure of other diodes.
Symptomatic Check before Proceeding:
Battery should be in good condition
and charged before testing the Alterna-
tor.
Check warning light indications.
Check belt condition and tension.
Check all cables and connections.
Check the battery for corrosion and dirty terminals.
Does the battery have a low state of charge? (See section 2 and 3)
Make sure all electrical items are off.
Check for Alternator noise.
ALTERNATIOR TEST
Use the (+Up and -Down) keys
to move cursor to the desired
test.
Start engine.
Allow the voltage to stabilize
until it stops rising. Press
(Y Enter)
Note:
Battery should be in good condition and charged before proceeding
with this test. Press (N Esc.) to return to main menu. Select
Alternator
Test
then press (Y Enter).
BATTERY TEST
STARTER TEST
>ALTERNATOR TEST
OTHER
>ALLOW VOLTAGE
TO STABILIZE
14.43V
‘Y’ TO CONTINUE.
START ENGINE.
‘N’ TO CANCEL
Allow the alternator to finish the test.
Test result will appear. The following are examples.
Alternator has GOOD regulation
and GOOD output.
High Regulation will damage the
system. Replace or repair the Alterna-
tor.
NOTE
1
:
Use the VOLT METER test as shown below and on page 18 to
obtain the actual diode ripple. Typically a ripple above 50mV indicates a
bad diode. If the system has a strong battery the ripple will be lower than
if the system has a weak battery.
NOTE
2
:
If the LCD reads "LOW OUTPUT" or "EST. OUTPUT" it is rec-
ommended that you run the test again with the engine at fast idle. If the
LCD still reads LOW OUTPUT turn on the accessories and select the
VOLT METER test as show below and on page 18.
Press (Y Enter).
Run this test with the accessories on and the engine at fast idle. If the voltage
drops below 13 volts the alternator does have LOW OUTPUT.
If Estimated Output is displayed the
output may be low for some systems.
In this case the Amps are displayed
for technician determination.
TESTING ALTER.
PLEASE WAIT…
#43 12V ALTER.
GOOD REG. 14.13V
GOOD DIODES
GOOD OUTPUT >50A
#43 12V ALTER.
LOW REG. 12.90V
BAD DIODE
LOW OUTPUT <30A
REVIEW/PRINT
>VOLT METER
DOWNLOAD/SETUP
ABOUT
#43 12V ALTER.
HIGH REG. 15.03V
GOOD DIODES
EST. OUTPUT 50A.
--VOLT METER--
VOLTS: 12.94V
RIPPLE 24.0mV
