ELECTRICAL TROUBLESHOOTING - continued - TM-9-2320-386-24-1-10092

TM 9-2320-386-24-1-1

0012 00

Electrical Troubleshooting (Contd)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

c. If battery voltage measures 28 0.2 Vdc and voltmeter on instrument panel shows

no voltage, an electrical problem exists between voltmeter and accessory/battery

switch. Go to malfunction 2, test 5, step 3.

d. If battery voltage measures between 26 and 30 Vdc, adjust voltage regulator in

alternator (Prestolite) (WP 0089 00) or (Leece-Neville) (WP 0090 00) until voltage

across batteries is 28 0.2 Vdc. Go to step 7 and check regulator stability.

e. If regulator voltage across batteries cannot be adjusted to 28 0.2 Vdc, replace

alternator (Prestolite) (WP 0089 00) or (Leece-Neville) (WP 0090 00).

f. If battery voltage is greater than 30 Vdc, first try to adjust voltage regulator

(TM 9-2320-361-20) in alternator down to 28 Vdc. If voltage regulator cannot be

adjusted to 28 Vdc, replace alternator (Prestolite) (WP 0089 00) or (Leece-Neville)

(WP 0090 00).

Step 7. Check voltage regulator stability as follows:

a. Decrease engine speed to 1000 rpm with headlights in ON position. Regulated

battery voltage should remain at 28.0 0.2 Vdc.

b. If battery voltage drops below 27.5 Vdc, replace alternator (Prestolite) (WP 0089 00)

or (Leece-Neville) (WP 0090 00).

c. Increase engine speed to 2000 rpm. Regulated battery voltage should remain at

28.0 0.2 Vdc.

d. If battery voltage increases above 28.5 Vdc, replace alternator (Prestolite)

(WP 0089 00) or (Leece-Neville) (WP 0090 00).

e. Return engine speed to 1200 rpm.

f. Turn headlights OFF and ON and observe change of battery voltage.

g. If battery voltage changes more than 0.5 Vdc and does not return quickly to

28.0 0.2 Vdc, replace alternator (Prestolite) (WP 0089 00) or (Leece-Neville)

(WP 0090 00).

Test 3. Test input voltage to alternator.

Step 1. Turn headlights to OFF position. Stop engine (TM 9-2320-386-10).

Step 2. Disconnect lead 1 from lead 568 at alternator.

Step 3. Turn accessory/battery switch to ON position.

Step 4. Check for battery voltage at contact end of lead 1. Voltage should be 24.0 Vdc.

a. If voltage is not present, an open lead or bad connection exists in input circuit. Go to

test 6.

b. If voltage is 24.0 Vdc (normal), remove access cover from top of alternator to expose

output terminals (Prestolite) (WP 0089 00) or (Leece-Neville) (WP 0090 00).

c. Connect lead 1 to lead 568, and go to step 5.

Step 5. Measure voltage at terminal end of lead 568.

a. If battery voltage is present (normal), the alternator is determined to be defective.

Go to test 4 and check positive output of alternator.

b. If voltage is not present, an open lead or bad contact exists in lead 568. Repair or

replace lead (WP 0125 00), and go to test 2 and retest.

Test 4. Test positive output of alternator.

0012 00-9