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Home >> Cadillac >> 2007 >> STS V >> Repair and Diagnosis >> Accessories & Equipment >> Interior/Illumination Lights >> Lighting System - Troubleshooting >> Headlamps Inoperative - Low Beams (Standard Headlamps)

Headlamps Inoperative - Low Beams (Standard Headlamps)

Headlamps Inoperative - Low Beams (Standard Headlamps)

Step Action Yes No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference: Lighting Systems Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle
2 Are both low beam headlamps inoperative? Go to Step 3  Go to Step 8 
3
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Turn ON the headlamps.
  4. With the scan tool, observe the Headlamp Switch parameter in the instrument panel module (IPM) Inputs data list.
Does the data parameter display ON?		 Go to Step 5  Go to Step 4 
4
  1. Turn OFF the ignition.
  2. Disconnect the turn signal/multifunction switch C3 harness connector.
  3. Connect a 3-amp fused jumper between the headlamp ON signal circuit and the ground circuit of the turn signal/multifunction switch at the C3 harness connector.
  4. Turn ON the ignition, with the engine OFF.
  5. With the scan tool, observe the Headlamp Switch parameter in the IPM inputs data list.
Does the Headlamp Switch parameter display ON?		 Go to Step 14  Go to Step 11 
5
  1. Turn OFF the ignition.
  2. Disconnect the headlamp LOW BEAM relay located in the underhood fuse block. Refer to Relay Replacement (Attached to Wire Harness) or Relay Replacement (Within an Electrical Center) .
  3. Connect a test lamp between the headlamp low beam relay control side supply voltage circuit and the headlamp low beam relay control circuit.
  4. Turn ON the ignition, with the engine OFF.
  5. Turn ON the low beam headlamps.
Does the test lamp illuminate?		 Go to Step 6  Go to Step 10 
6 Connect a test lamp between the headlamp low beam relay switch side supply voltage circuit and ground.
Does the test lamp illuminate?		 Go to Step 7  Go to Step 19 
7
  1. Turn OFF the ignition.
  2. Connect a 40-amp fused jumper between the headlamp low beam relay switch side supply voltage circuit and the headlamp low beam supply voltage circuit.
  3. Turn ON the ignition, with the engine OFF.
Do both of the low beam headlamps illuminate?		 Go to Step 15  Go to Step 8 
8
  1. Disconnect the inoperative low beam headlamp bulb.
  2. Connect a test lamp between the low beam headlamp supply voltage circuit at the inoperative low beam headlamp bulb and the ground circuit of the inoperative low beam headlamp bulb.
Does the test lamp illuminate?		 Go to Step 17  Go to Step 9 
9 Test the headlamp low beam supply voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 24  Go to Step 18 
10 Test the headlamp low beam relay control circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 24  Go to Step 13 
11 Test the turn signal/multifunction switch ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 24  Go to Step 12 
12 Test the turn signal/multifunction switch headlamp ON signal circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 24  Go to Step 13 
13 Test the twilight sentinel delay signal circuit of the IPM for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 24  Go to Step 16 
14 Inspect for poor connections at the C 3 harness connector of the turn signal/multifunction switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 24  Go to Step 20 
15 Inspect for poor connections at the headlamp low beam relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 24  Go to Step 21 
16 Inspect for poor connections at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 24  Go to Step 22 
17 Inspect for poor connections at the harness connector of the inoperative low beam headlamp bulb. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 24  Go to Step 23 
18 Locate and repair an open or high resistance in the headlamp ground circuit. Refer to Circuit Testing and Wiring Repairs .
Did you complete the repair?		 Go to Step 24  -
19 Locate and repair an open or high resistance in the switch side supply voltage circuit of the headlamp low beam relay. Refer to Circuit Testing and Wiring Repairs .
Did you complete the repair?		 Go to Step 24  -
20 Replace the turn signal/multifunction switch. Refer to Turn Signal Multifunction Switch Replacement .
Did you complete the replacement?		 Go to Step 24  -
21 Replace the headlamp low beam relay. Refer to Relay Replacement (Attached to Wire Harness) or Relay Replacement (Within an Electrical Center) .
Did you complete the replacement?		 Go to Step 24  -
22 Replace the IPM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 Go to Step 24  -
23 Replace the inoperative low beam headlamp bulb. Refer to Headlamp Bulb Replacement (Lo Beam) or Headlamp Bulb Replacement (Hi Beam) .
Did you complete the replacement?		 Go to Step 24  -
24 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 2 
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