Associated Equipment 6042 - Manual (Page 6)

6
OUTPUT VOLTAGE TEST:
1) Connect tester to battery as shown. Connect AMPS PICKUP
around positive output cable of alternator. If wires split off to
feed power to accessories, the pickup must be placed over the
wires between the point the split and the alternator. Do not
place the pickup closer than 6 inches to the alternator or the
current readings may be affected by the magnetic field of the
alternator.
2) VOLTS switch should be in INT position.
3) Make sure all accessories are off in the vehicle.
4) Start vehicle and allow the engine to run at fast idle until the
current output from the alternator is between 0-10 amps. Read
the output voltage. Proper output voltages should be as listed
previously.
REMEMBER: Charging systems in a vehicle will compensate
for ambient temperatures by increasing the charging voltage at
low temperatures. Check the vehicle service manual for proper
charging voltages at low temperatures.
OUTPUT CURRENT TEST:
Connect the tester as above and run the vehicle at fast idle. Apply a
load to the battery to obtain the highest reading on the ammeter. Do
not allow the battery voltage to drop below 12.0 volts. This ammeter
reading is the maximum output of the alternator.
It should be within 10% of the manufacturer's specification to be
acceptable. If a number of accessories have been added to the
vehicle, the alternator output should be high enough to supply the
total accessory load.
OUTPUT DIODE/STATOR TEST:
1) Attach the tester as shown in the above diagram. Attach the
light gauge positive lead to the positive output terminal of the
alternator. Attach the light gauge negative lead to the frame
(ground) of the alternator. VOLTS switch should be on EXT
position.
2) Start vehicle and run at a fast idle. Apply a load to the battery
as described in the OUTPUT CURRENT TEST.
3) Defective output diodes or a stator problem will turn the
DEFECTIVE DIODE light on in 1-2 seconds and it will glow
steadily. If the light blinks on and then stays off, there are no
defective parts.
4) If the positive output terminal of the alternator is inaccessible,
the positive lead may be connected to the positive terminal of
the battery and the test run as described. The accuracy of the
test may be affected by loose or corroded terminals or an
undersized cable. Attach leads to rear of alternator if possible.
GM DIODE TRIO TEST:
The diode is located inside the GM alternator and must be checked
The diode trio is located inside a GM alternator and must be
checked whenever alternator problems are suspected. These
diodes are separate from the output rectifier of the alternator. They
are used as part of a feedback loop to the internal regulator.
1)
Attach the heavy gauge leads to the battery.
2) VOLTS switch should be in EXT position.
3) Attach the black light gauge lead to the negative battery post or
frame of alternator.
4) Attach the red light gauge to the number 1 terminal of the plug
in the alternator. DO NOT DISCONNECT THE PLUG FROM
THE ALTERNATOR. DAMAGE MAY RESULT IF THE PLUG
IS DISCONNECTED.
5) Start the engine and let run at normal idle. Do not apply any
load to the battery.
6) If the DEFECTIVE DIODE light comes on and stays on, it
indicates a defective diode trio. The alternator should be
repaired or replaced.
ALTERNATOR OUTPUT TEST: (Bypassing the regulator)
If the alternator did not pass the first output test that was
run, this test should be performed to determine whether
the alternator or regulator is at fault. Determine from the
vehicle service manual whether the regulator is type "A" or
"B".
1)
Connect the unit to the vehicle as shown (See figure
11).
2) Disconnect the lead wire from the field terminal of the
alternator or regulator.
3) Attach the blue test lead to the field terminal of the
alternator or, if disconnected at the regulator, the
wire that leads from the regulator to the field terminal.
(IF THE LEAD FROM THE REGULATOR IS NOT
DISCONNECTED AT ONE END OR THE OTHER,
DAMAGE MAY OCCUR TO THE UNIT WHEN TESTING.)
4) Start the engine and adjust engine speed to about 2000 RPM.
5) Apply a load to the battery to reduce the system voltage by
about 2 volts.
6) Hold the spring loaded FIELD selector switch in the proper
position. In the "A" position, the field lead is connected to the
negative terminal. In the "B" position, the field lead is
connected to the positive terminal. This is called "full fielding"
the alternator. Pushing the switch into the wrong position will
not damage the alternator.
7) Adjust the lead applied to the battery to give the maximum
current reading without dropping the voltage below 12.0 volts.
8) Release the FIELD switch and turn off the load on the battery.
9) If the alternator output is not at least tested 90% of its rated
output, repair or replace the alternator. If the current reading
on the ammeter is within 10% of the manufacturer's rating, the
alternator is good and the regulator should be replaced if the
wiring to it is found to be good by these checks.
FIGURE 10
TERMINAL 1
ALTERNATOR
PLUG
SCREWDRIVER
RED LEAD
FIGURE 11
FIELD WIRE
FROM ALTERNATOR
TO REGULATOR
REGULATOR
F
F
FRAME
ALTERNATOR
+ -
FRAME