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Home >> Cadillac >> 2004 >> CTS Base, 3.6 7 >> Repair and Diagnosis >> Accessories & Equipment >> Interior/Illumination Lights >> Lighting Systems (Symptoms) >> Headlamps Always On - Low or High Beam

Headlamps Always On - Low or High Beam

Headlamps Always On - Low or High Beam

Step Action Yes No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics and Wiper/Washer System Schematics in Wipers/Washer Systems
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 the headlamp switch to the OFF position.
  2. Verify that the transmission shift lever is in the PARK position for vehicles equipped with automatic transmissions or the parking brake is applied for vehicles with manual transmissions.
  3. Expose the sunload sensor to a bright light.
  4. Turn the windshield wipers to the OFF position.
  5. Turn ON the ignition, with the engine OFF.
Are the head lamps ON?		 Go to Step 3  Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
3
  1. Turn OFF the ignition.
  2. Install a scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. Turn the headlamp switch to the OFF position.
  5. With a scan tool, observe the Head Lamp Switch parameter in the Dash Integration Module (DIM) Inputs data list.
Does the scan tool indicate that the Head Lamp Switch parameter is OFF?		 Go to Step 4  Go to Step 13 
4 With a scan tool, observe the Low/High Beam Relay parameter in the DIM Outputs data list.
Does the scan tool indicate that the Low/High Beam Relay output parameter is OFF?		 Go to Step 8  Go to Step 5 
5 With a scan tool, observe the Lights On with Wipers parameter in the DIM Inputs data list.
Does the scan tool indicate OFF?		 Go to Step 6  Go to Step 14 
6 With the scan tool, observe the Flash to Pass Switch parameter in the DIM Inputs data list.
Does the scan tool indicate that the Flash to Pass Switch parameter is OFF?		 Go to Step 15  Go to Step 7 
7 With a scan tool, observe the Twilight Switch status in the DIM Inputs data list.
Does the scan tool indicate that the Twilight Switch is OFF?		 Go to Step 23  Go to Twilight Sentinel Inoperative 
8 Are the high beam headlamps ON? Go to Step 11  Go to Step 9 
9
  1. Turn OFF the ignition.
  2. Disconnect the headlamp low beam relay.
  3. Turn ON the ignition, with the engine OFF.
Did the low beam headlamps turn OFF?		 Go to Step 10  Go to Step 24 
10
  1. Turn OFF the ignition.
  2. Connect a test lamp between the coil side supply voltage circuit and the headlamp low beam relay control circuit of the headlamp low beam relay.
  3. Turn ON the ignition, with the engine OFF.
Did the test lamp illuminate?		 Go to Step 16  Go to Step 20 
11
  1. Turn OFF the ignition.
  2. Disconnect the headlamp high beam relay.
  3. Turn ON the ignition, with the engine OFF.
Did the high beam headlamps turn OFF?		 Go to Step 12  Go to Step 25 
12
  1. Turn OFF the ignition.
  2. Connect a test lamp between the coil side supply voltage circuit of the headlamp high beam relay and the high beam headlamp relay control circuit of the headlamp high beam relay.
  3. Turn ON the ignition, with the engine OFF.
Did the test lamp illuminate?		 Go to Step 17  Go to Step 21 
13
  1. Turn OFF the ignition.
  2. Disconnect the multifunction, turn signal switch.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool observe the Head Lamp Switch parameter in the DIM Inputs data list.
Does the scan tool indicate that the Head Lamp Switch parameter is OFF?		 Go to Step 22  Go to Step 18 
14 Test the windshield wiper switch ON signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 30  Go to Step 23 
15
  1. Disconnect the multifunction, turn signal switch.
  2. With a scan tool observe the Flash to Pass Switch parameter in the DIM Inputs data list.
Does the scan tool indicate that the Flash to Pass Switch is OFF?		 Go to Step 22  Go to Step 19 
16 Test for a short to ground in the headlamp 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 30  Go to Step 23 
17 Test for a short to ground in the headlamp high beam relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 30  Go to Step 23 
18 Test for a short to ground in the headlamp switch headlamp ON signal circuit of the multifunction, turn signal switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 30  Go to Step 23 
19 Test for a short to ground in the flash to pass switch signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 30  Go to Step 23 
20 Inspect for poor connections 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 30  Go to Step 26 
21 Inspect for poor connections at the high 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 30  Go to Step 27 
22 Inspect for poor connections at the harness connector of the multifunction, turn signal 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 30  Go to Step 28 
23 Inspect for poor connections at the harness connector of the DIM. 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 30  Go to Step 29 
24 Repair the short to voltage in the headlamp low beam supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 30  -
25 Repair the short to voltage in the headlamp high beam supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 30  -
26 Replace the headlamp 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 30  -
27 Replace the headlamp high 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 30  -
28 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 30  -
29
IMPORTANT: Perform the setup procedure for the DIM.
Replace the DIM. Refer to Dash Integration Module Replacement in Body Control System.Did you complete the replacement?		 Go to Step 30  -
30 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 2 
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