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1G-287 4/96
26-SI ALTERNATOR
TROUBLESHOOTING
Trouble in the charging system will normally be indicated
by one of the following:
• Indicator light “on” with engine running.
• Indicator light “off” with key on, engine not running.
• Undercharged or overcharged battery.
• Short life of light bulbs or other electric equipment
caused by abnormally high system voltage.
• System voltmeter readings outside normal range.
• Incorrect or no operation of accessories connected to
alternator “R” terminal.
Diagnose system as follows: (See Fig. 8)
A. ALL CHARGING SYSTEMS -
TEST EQUIPMENT NEEDED:
• Belt Tension Gage
• Battery State-of-Charge Indicator
1. Check electrical system wiring and battery terminals
for poor connections or other obvious conditions that
might result in shorts, opens, grounds, or high resistance.
Correct as necessary.
2. Check alternator drive belt for proper tension. Adjust
to manufacturer's specifications.
3. Check battery for state-of-charge. If low, recharge
according to manufacturer’s specifications and load
test to establish serviceability. Further diagnostic tests
require a known good, fully-charged battery for accurate
results.
B. SYSTEMS WITH INDICATOR LIGHT -
TEST EQUIPMENT NEEDED:
• Jumper Lead with 5-Amp Fuse
1. If indicator light is on with engine running:
Stop engine. Turn key switch to “run” position. Indicator
light should be on. If not, go to Step 3.
Disconnect indicator light lead at alternator. This will
be the “I” terminal connector.
If indicator light remains on, locate and correct shorted
or grounded condition in indicator light circuit between
the light and the alternator.
If indicator light goes out, light is working properly.
Proceed to “C.” for check of system with indicator light
working properly.
2. If indicator light does not come on with the key switch
in the “run” position with the engine stopped (“bulb
check” mode):
Leave key in “run” position with engine stopped.
Disconnect indicator light lead from alternator. This
will be at the “I” terminal. Use fused (5-amp) jumper
lead to ground indicator lamp circuit in harness
connector to ground screw or other clean metal ground
on alternator housing.
- If indicator light comes on with jumper lead in place,
repair or replace alternator as described under Unit
Repair.
Figure 8. Troubleshooting a 26-SI System
4
INDICATOR
LIGHT
KEY
SWITCH
FUSE
BLOCK
INDICATOR
LIGHT ("I")
CONNECTOR
TERMINAL
CONNECTOR
(DISCONNECTED)
B2, B3
FUSE
OUTPUT
TERMINAL
GENERATOR
E1
BATTERY
"R" or "I"
TERMINAL
INDICATOR
LIGHT
CIRCUIT
VOLTMETER
D3,E2
D2
26-5016