For 1990-2009 cars

Symptom | Procedure
--- | ---
Important: If you disconnect either side high beam headlamp with ignition On, headlamps will not operate when you reconnect the connector until you cycle the key.
Low beam headlamps inoperative, high beam OK. | Disconnect headlamp/turn switch connector. Probe cavity 5 circuit 1201 with a test light-to-ground. Does lamp light? If yes, faulty headlamp/turn switch. If no, open circuit 1201.
High beam headlamps inoperative, low beam OK. | Disconnect headlamp/turn switch connector. Probe cavity 7 circuit 1200 with a test light-to-ground. Does lamp light? If yes, faulty headlamp/turn switch. If no, open circuit 1200.
High and low beam headlamps inoperative. | Check circuit 550 at headlamp switch for an open. If OK, faulty headlamp switch.
High beam indicator does not operate. | Cluster test using Tech 2. If High beam indicator does not work with cluster test, faulty cluster. Refer to I/P section of this service manual.
Right high beam headlamp, DRL, inoperative. | Check right high beam headlamp for open element. If OK, check for open 593 or 1200 circuit.
Left high beam headlamp, DRL, inoperative. | Check left high beam headlamp for open element. If OK, check for open circuit 40 or open circuit 1200.
DRL Inoperative:
DTC B2600 | Chart 1
DTC B2602 | Chart 2
DTC B2603 | Chart 3
DRL On with headlamp switch On, dimmer switch in low position. | Using Scan tool, observe high beam input. If voltage is between 6-8 volts, disconnect BCM connector J3 (PNK 24 way) using a DVOM, check CKT 592, Green wire for short to ground. If OK, faulty BCM.
DRL inoperative, high beam indicator On with headlamp switch in any position. | Disconnect BCM connector J1. Probe circuit 1200 with a test light to B+. Turn the headlamp switch On, dimmer switch in the high beam position. Does lamp light? If no, open circuit 1200. If yes, faulty connection or BCM.
DRL lamps do not turn Off with park brake applied. | Disconnect BCM connector J2. Probe circuit 1134 with a test light to B+. Apply parking brake. Does lamp light? If no, open circuit 1134. If yes, faulty connection or BCM.