Operation CHARM: Car repair manuals for everyone.
Home >> Cadillac >> 2007 >> XLR V8-4.6L >> Repair and Diagnosis >> Lighting and Horns >> Testing and Inspection >> Symptom Related Diagnostic Procedures >> Turn Signal Lamps and/or Indicators Malfunction

Turn Signal Lamps and/or Indicators Malfunction



TURN SIGNAL LAMPS AND/OR INDICATORS MALFUNCTION

DIAGNOSTIC INSTRUCTIONS
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.




DIAGNOSTIC FAULT INFORMATION

CIRCUIT/SYSTEM DESCRIPTION
Ground is applied at all times at G201 to the turn signal/multifunction switch. The turn signal lamps may only be activated with the ignition switch in the ON or START position. When the turn signal/multifunction switch is placed in either the TURN RIGHT or TURN LEFT position, ground is applied to the body control module (BCM) through either the right turn or left turn signal switch signal circuit. The BCM then applies a pulsating voltage to the front and rear turn signal lamps through there respective voltage supply circuits. Ground for the left front turn signal lamp is supplied at G101. Ground for the right front turn signal lamp is supplied at G102. Ground for the rear turn signal lamps is supplied at G301 for the left and G302 for the right. For more detailed information concerning turn signal lamp operation refer to Exterior Lighting Systems Description and Operation.

CIRCUIT/SYSTEM VERIFICATION
Ignition ON, observe the scan tool Right and Left Turn Signal Switch parameters while cycling the turn signal switch between the left and right positions. The readings should toggle between ACTIVE and INACTIVE.
- If the readings do not change between the commanded states, refer to Turn Signal Switch Malfunction.
- If the readings change between the commanded states and the turn signal indicators are inoperative, refer to Turn Signal Indicators Malfunction.

CIRCUIT/SYSTEM TESTING

TURN SIGNAL SWITCH MALFUNCTION
1. Ignition OFF, disconnect the C4 harness connector at the turn signal/multifunction switch.
2. Test for less than 1 ohm of resistance between the ground circuit terminal G and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool left turn signal switch parameter is INACTIVE.
- If not the specified value, test the signal circuit terminal F for a short to ground. If the circuit tests normal, replace the BCM.
4. Verify the scan tool right turn signal switch parameter is INACTIVE.
- If not the specified value, test the signal circuit terminal H for a short to ground. If the circuit tests normal, replace the BCM.
5. Install a 3A fused jumper wire between the signal circuit terminal F and ground. Verify the scan tool left turn signal switch parameter is ACTIVE.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
6. Install a 3A fused jumper wire between the signal circuit terminal H and ground. Verify the scan tool right turn signal switch parameter is ACTIVE.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
7. If all circuits test normal, test or replace the turn signal/multifunction switch.

Turn Signal Lamps Malfunction
1. Ignition OFF, disconnect the harness connector at the inoperative turn signal lamp.
2. Test for less than 1 ohm of resistance between the ground circuit and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit and the ground circuit.
4. Command the appropriate turn signal lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
- If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the appropriate turn signal lamp assembly.

TURN SIGNAL INDICATORS MALFUNCTION
Ignition ON, with a scan tool perform the display test for the instrument panel cluster (IPC) and observe the turn signal lamp indicators.
- If the turn signal lamp indicators illuminate during the test, replace the BCM.
- If the turn signal lamp indicators do not illuminate during the test or remain illuminated at all times, replace the IPC.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
- Tail/Turn Signal Lamp Replacement
- Turn Signal Multifunction Switch Replacement
- Control Module References for BCM or IPC replacement, setup, and programming. Programming and Relearning
pro multis · About Operation CHARM