Piper CHEROKEE WARRIOR PA-28-151 1995 Maintenance Manual page 423

PIPER CHEROKEE WARRIOR SERV I C E M A N U A L
f. With the alternator turning at sufficient rpm to produce a half load condition or approximately 25
amperes output, the voltmeter should read between 13.6 and 14.3 volts. The ambient temperature around the
voltage regulator should be between 50° F and 100° F while this test is being made.
g. The voltage regulator heat sink, or case, is the ground connection for the electronic circuit.
Therefore, if this unit is tested on the bench, it is important that a wire, No. 14 or larger be connected between
the regulator case and the alternator. If the regulator does not regulate between 13.6 and 14.4 volts, one of the
following conditions exists:
1. Regulates, but out of specification. The regulator is out of calibration and must be replaced.
2. The voltmeter continues to read battery voltage.
A. Poor or open connections within the wiring harness.
B. The regulator is "open".
3. Voltage continues to rise.
A. Regulator housing not grounded.
B. Regulator shorted, it must be replaced.
h. Check the following in the event of test failure:
1. Poor or loose connections.
2. Poor ground on the regulator housing.
3. Shorted alternator windings.
4. A grounded output or input wire. (This will cause instantaneous failure).
5. Disconnecting the regulator while the circuit is energized.
6. Open circuit operation of the alternator. (The battery disconnected)
11-61. TESTING LAMAR 14 VOLT SYSTEM REGULATORS (Refer to Figure 11-44)
a. Use only a good quality, adjustable dc power source.
b. This test must be accomplished with the regulator out of the circuit.
c. Connect regulator into circuit after completing test.
When testing the alternator control with an operating alternator,
never bypass the regulator bus to field (RED to BLUE) to
check operation of the alternator or the overvoltage protection
action.
d. Use two quality, accurate voltmeters with at least a 15-volt scale.
Ambient temperatures surrounding voltage regulator must be
between 50°F and 100°F.
Do not connect the voltmeter across the battery. The regulator
is designed to compensate for resistance in wiring harness.
Revised: February 28, 1995
CAUTION
CAUTION
CAUTION
2F16
Island Enterprises
ELECTRICAL SYSTEM