Generator Diagnosis And Testing; Generator Output Test; Generator Voltage Test - Ford LRG-423 Service Manual

03-72
Auxiliary Systems
03-72
GENERATOR DIAGNOSIS ANDTESTING
NOTE: The generator (main) wiring diagram (14305)
for the engine, is found later in this section.
Before performing generator tests on the unit, note
conditions such as: slow cranking, dead battery,
charge indicator lamp stays on with engine running,
etc. This information will aid in isolating the part of the
,
system causing the symptom.
J5695-A
Item
Part
Number
Description
1 -
Mounting Screws (Ground
Connection) (4 req' d) Tighten to
1.7-2.8 Nom (15-25 In-Lb) (Part
of 10316)
2 - Brush Holder Screw (Test Point
" F" ) (Part of 10316)
3 -
Brush Holder Screw (Test Point
" A" ) (Part of 10316)
4 -
I Circuit 904 (Part of 14305)
5 -
S Circuit 4 (Part of 14305)
6 - A Circuit 36 (Part of 14305)
7 10328
Rotor Slip Ring
Visuall inspection
Preliminary checks to the charging system should be
made regardless of the fault condition. These checks
include:
1. Check battery posts and cable terminals for clean
and tight connections. Clean the posts and the
cables to ensure good electrical contact.
2. Check for secure connections at the generator
output, regulator, and engine ground. Also check
the connection at the load distribution point
(starter relay).
3. Check the fuses/fuse links and wiring to the
generator to ensure that they are not burned or
damaged. This condition, resulting in an open
circuit or high resistance, can cause erratic or
intermittent charging system concerns.
4.
Check the battery voltage. If the voltage is less
than 12.3 volts with the engine and all
accessories off, charge battery before
proceeding.
In order to check the generator, the use of Rotunda
Starting and Charging System Tester 078-00005
(VAT-40) or equivalent, is recommended.
Generator Output Test
NOTE: Refer to the test equipment user' s manual for
complete directions on examining the charging
system.
1. Switch the tester to ammeter function.
2. Connect the positive and negative leads of the
tester to the battery.
3. Connect current probe to generator B+ output
lead Circuit 38 (BWO (to measure generator
output).
4. With the engine running at 2000 rpm, adjust the
VAT-40 or equivalent load bank to determine the
output of the generator. Generator output should
be greater than values given in graph below. If
not, refer to symptom chart in this section for
diagnostic procedure.
Generator Voltage Test
1. Switch the tester to the voltmeter function.
2. Connect the positive lead to the generator
A-terminal connector and the negative lead to
ground.
AMPS
95 AMP GENERATMI
loo0 1500
ENGINE SPEED
3. Turn off all electrical accessories.
NOTE: During this check, the voltage may be between
13.0-15.5 volts. If voltages are out of range, refer to
symptom chart in this section for diagnostic procedure.
4. With the engine running at 2000 rpm, check the
generator voltage.