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Headlamps Inoperative - Low Beams

WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
Headlamps Inoperative - Low Beams

Step Action Yes No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics 
Connector End View Reference: Master Electrical Component List in Wiring Systems.
1 Did you perform the Lighting System Diagnostic System Check? Go to Step 2  Go to Diagnostic System Check - Lighting Systems 
2
  1. Turn ON the headlamps.
  2. Ensure that the headlamp dimmer switch is in the LOW position.
Do both low beam headlamps illuminate?
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3 Is only one low beam headlamp inoperative? Go to Step 12  Go to Step 4 
4
  1. Disconnect the BCM connector C1.
  2. Connect a jumper between the headlamp low beam relay control circuit and ground.
Do the low beam headlamps illuminate?
Go to Step 5  Go to Step 7 
5
  1. Reconnect the BCM connector C1.
  2. Disconnect the multifunction switch.
  3. Install a jumper between the headlamp switch headlamps ON signal circuit and ground.
Do the low beam headlamps illuminate?
Go to Step 9  Go to Step 6 
6 Test for a poor connection, open or short to battery voltage, in the headlamp switch headlamps ON signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 18  Go to Step 13 
7
  1. Remove the low beam headlamp relay.
  2. Install a fused jumper between the battery positive voltage supply circuit and the switched low beam voltage supply circuit.
Do the low beam headlamps illuminate?
Go to Step 8  Go to Step 11 
8 Test for a poor connection, open or a short to battery positive voltage in the low beam relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 19  Go to Step 10 
9 Inspect for a poor connection at the harness connector of the headlamp dimmer switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 19  Go to Step 14 
10 Inspect for a poor connection at the low beam relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 19  Go to Step 15 
11 Inspect for a poor connection at the harness connector of the underhood fuse block. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 19  Go to Step 17 
12 Inspect the inoperative low beam headlamp voltage supply and ground circuit for a high resistance, short to ground, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 19  Go to Step 16 
13 Test for a short to ground or a short to battery positive voltage in the exterior lamps OFF input circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 19  Go to Step 18 
14 Replace the multifunction turn signal switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column.
Did you complete the replacement?
Go to Step 19  -
15 Replace the low beam relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems.
Did you complete the replacement?
Go to Step 19  -
16 Replace the inoperative low beam headlamp. Refer to Headlamp Assembly or Headlamp Bulb Replacement .
Did you complete the replacement?
Go to Step 19  -
17 Replace the underhood fuse block. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Did you complete the replacement?
Go to Step 19  -
18
IMPORTANT: Perform the setup procedure for the BCM. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.
Replace the BCM. Refer to Body Control Module Replacement in Body Control System.Did you complete the replacement?
Go to Step 19  -
19 Operate the system in order to verify the repair.
Did you correct the condition?
System OK Go to Step 3