LAMP DIAGNOSIS
TABLE OF CONTENTS
page
DIAGNOSIS AND TESTING
SYSTEM DIAGNOSIS ......................2
DIAGNOSIS AND TESTING
SYSTEM DIAGNOSIS
A good ground is necessary for proper lighting
operation. Grounding is provided by the lamp socket
when it comes in contact with the metal body, or
through a separate ground wire.
Always begin any diagnosis by testing all of the
fuses and circuit breakers in the system. Refer to
Group 8W, Wiring Diagrams.
HEADLAMP
CONDITION POSSIBLE CAUSES CORRECTION
HEADLAMPS ARE DIM
WITH ENGINE IDLING
1. Loose or corroded battery cables. 1. Clean and secure battery cable clamps
and posts.
OR IGNITION TURNED
OFF
2. Loose or worn generator drive
belt.
2. Adjust or replace generator drive belt.
3. Charging system output too low. 3. Test and repair charging system, refer to
Group 8A,
4. Battery has insufficient charge. 4. Test battery state-of -charge
, refer to Group 8A.
5. Battery is sulfated or shorted. 5. Load test battery, refer to Group 8A.
6. Poor lighting circuit Z3-ground. 6. Test for voltage drop across Z3-ground
locations, refer to Group 8W.
7. Both headlamp bulbs defective. 7. Replace both headlamp bulbs.
HEADLAMP BULBS BURN
OUT
1. Charging system output too high. 1. Test and repair charging system, refer to
Group 8A.
FREQUENTLY 2. Loose or corroded terminals or
splices in circuit.
2. Inspect and repair all connectors and
splices, refer to Group 8W.
HEADLAMPS ARE DIM
WITH ENGINE RUNNING
1. Charging system output too low. 1. Test and repair charging system, refer to
Group 8A.
ABOVE IDLE* 2. Poor lighting circuit Z3-ground. 2. Test for voltage drop across Z3-ground
locations, refer to Group 8W.
3. High resistance in headlamp
circuit.
3. Test amperage draw of headlamp circuit.
4. Both headlamp bulbs defective. 4. Replace both headlamp bulbs.
HEADLAMPS FLASH
RANDOMLY
1. Poor lighting circuit Z3-ground. 1. Test for voltage drop across Z3-ground
locations, refer to Group 8W.
2. High resistance in headlamp
circuit.
2. Test amperage draw of headlamp circuit.
3. Loose or corroded terminals or
splices in circuit.
3. Inspect and repair all connectors and
splices, refer to Group 8W.
8L - 2 LAMPS DN
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