FOG LAMP DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
FOG LAMPS ARE DIM
WITH ENGINE IDLING OR
IGNITION TURNED OFF.
1. Loose or corroded battery cables. 1. Clean and secure battery cable clamps
and posts.
2. Loose or worn alternator drive
belt.
2. Adjust or replace alternator 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 Z1-ground. 6. Test for voltage drop across Z1-ground
locations. Refer to Group 8W.
FOG LAMP BULBS BURN
OUT FREQUENTLY
1. Charging system output too high. 1. Test and repair charging system. Refer to
Group 8A.
2. Loose or corroded terminals or
splices in circuit.
2. Inspect and repair all connectors and
splices. Refer to Group 8W.
FOG LAMPS ARE DIM
WITH ENGINE RUNNING
ABOVE IDLE
1. Charging system output too low. 1. Test and repair charging system. Refer to
Group 8A.
2. Poor lighting circuit Z1-ground. 2. Test for voltage drop across Z1-ground
locations. Refer to Group 8W.
3. High resistance in fog lamp circuit. 3. Test amperage draw of fog lamp circuit.
FOG LAMPS FLASH
RANDOMLY
1. Poor lighting circuit Z1-ground. 1. Test for voltage drop across Z1-ground
locations. Refer to Group 8W.
2. High resistance in fog lamp circuit. 2. Test amperage draw of fog lamp circuit.
3. Faulty fog lamp switch. 3. Replace fog lamp switch.
4. Loose or corroded terminals or
splices in circuit.
4. Inspect and repair all connectors and
splices. Refer to Group 8W.
FOG LAMPS DO NOT
ILLUMINATE
1. Blown fuse for fog lamp. 1. Replace fuse. Refer to Group 8W.
2. No Z1-ground at fog lamps. 2. Repair circuit ground. Refer to Group
8W.
3. Faulty fog lamp switch. 3. Replace fog lamp switch.
4. Broken connector terminal or wire
splice in fog lamp circuit.
4. Repair connector terminal or wire splice.
5. Defective or burned out bulb. 5. Replace bulb.
LH LAMPS 8L - 3
DIAGNOSIS AND TESTING (Continued)
2000 LHS, 300M, CONCORDE AND INTREPID