Turn Signal Lamps and/or Indicators Malfunction
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Turn Signal Lamps and/or Indicators Malfunction
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Diagnostic Fault Information
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Circuit
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Short to Ground
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Open/High Resistance
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Short to Voltage
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Signal Performance
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Left Turn Signal Switch Signal
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2
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2
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2
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-
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Right Turn Signal Switch Signal
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3
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3
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3
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-
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Left Front Turn Signal Lamp Control
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B3948 02
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4
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4
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-
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Right Front Turn Signal Lamp Control
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B3949 02
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5
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5
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-
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Left Rear Turn Signal Lamp Control
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B3950 02
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6
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6
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-
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Right Rear Turn Signal Lamp Control
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B3951 02
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7
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7
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-
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Left Repeater Lamp Control
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B3948 02
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8
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8
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-
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Right Repeater Lamp Control
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B3949 02
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9
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9
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-
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Turn Signal/Multifunction Switch Ground
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-
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1
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-
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-
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Left Tail Lamp Ground
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-
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6
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-
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-
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Left Repeater Lamp Ground
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-
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8
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-
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-
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Right Repeater Lamp Ground
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-
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9
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-
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-
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Right Tail Lamp Ground
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-
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7
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-
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-
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1. All Turn Signals Lamps and/or Indicators Inoperative
2. Left Turn Signals Malfunction
3. Right Turn Signals Malfunction
4. Left Front Turn Signal Malfunction
5. Right Front Turn Signal Malfunction
6. Left Rear Turn Signal Malfunction
7. Right Rear Turn Signal Malfunction
8. Left Repeater Lamp Malfunction
9. Right Repeater Lamp Malfunction
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Circuit/System Description
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Ground is applied at all times 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 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. When a turn signal request is received by the BCM, a serial data message is sent to the instrument cluster requesting the respective turn signal indicator be pulsed ON and OFF.
Schematic Reference
Exterior Lights Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References
for scan tool information
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Circuit/System Verification
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1.
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Ignition ON, observe the scan tool Left Turn Signal Switch parameter while moving the turn signal switch from the center position to the left position. The value should be Inactive and change to Active.
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2.
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If the value does not change, refer to Turn Signal Switch Malfunction.
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3.
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Ignition ON, observe the scan tool Right Turn Signal Switch parameter while moving the turn signal switch from the center position to the right position. The value should be Inactive and change to Active.
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4.
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If the value does not change, refer to Turn Signal Switch Malfunction.
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5.
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Ignition ON, with the turn signal switch in the left position, observe the function of the E4LF turn signal lamp-left front, the E4Y turn signal repeater lamp-left and the E4LR turn signal lamp-left rear. Each lamp should flash ON and OFF.
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6.
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If a lamp is always On or always OFF, refer to Turn Signal Lamps Malfunction.
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7.
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Ignition ON, with the turn signal switch in the right position, observe the function of the E4RF turn signal lamp-right front, the E4Z turn signal repeater lamp-right and the E4RR turn signal lamp-right rear. Each lamp should flash ON and OFF.
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8.
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If a lamp is always On or always OFF, refer to Turn Signal Lamps Malfunction.
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9.
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Command the All Indicators Test ON and OFF with a scan tool. The left and right turn signal indicators should turn ON and OFF when changing between the commanded states.
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10.
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If the left and right turn signal indicators are always ON or always OFF, replace the P16 instrument cluster.
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Turn Signal Switch Malfunction
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1.
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Ignition OFF, disconnect the X2 harness connector at the S78 turn signal/multi-function switch.
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2.
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Test for less than 30 Ω between the ground circuit terminal 3 and ground.
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3.
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If greater than the specified range, test the ground circuit for an open/high resistance.
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4.
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Ignition ON, verify the scan tool Left Turn Signal Switch parameter is Inactive.
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5.
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If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K9 BCM.
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6.
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Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Left Turn Signal Switch parameter is Active.
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7.
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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 K9 BCM.
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8.
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Verify the scan tool Right Turn Signal Switch parameter is Inactive.
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9.
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If not the specified value, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, replace the K9 BCM.
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10.
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Install a 3 A fused jumper wire between the signal circuit terminal 7 and ground. Verify the scan tool Right Turn Signal Switch parameter is Active.
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11.
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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 K9 BCM.
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12.
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If all circuits test normal, test or replace the S78 turn signal/multi-function switch.
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Turn Signal Lamps Malfunction
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1.
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Ignition OFF, disconnect the harness connector at the appropriate turn signal lamp.
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2.
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Test for less than 30 Ω between the ground circuit terminal listed below and ground.
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•
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E4Y turn signal repeater lamp-left terminal 2
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E4Z turn signal repeater lamp-right terminal 2
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E4LR turn signal lamp-left rear terminal 1
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E4RR turn signal lamp-right rear terminal 1
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3.
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If greater than the specified range, test the ground circuit for an open/high resistance.
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4.
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Disconnect the inline harness connector at the appropriate E4LF turn signal lamp-front listed below:
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E4LF turn signal lamp-left front X115 (Without TT6/TT7/TT8)
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•
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E4LF turn signal lamp-left front X111 (With TT6/TT7/TT8)
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•
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E4RF turn signal lamp-right front X116 (Without TT6/TT7/TT8)
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•
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E4RF turn signal lamp-right front X112 (With TT6/TT7/TT8)
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5.
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Connect a test lamp between the control circuit terminal listed below and ground.
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E4LF turn signal lamp-left front terminal J
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E4RF turn signal lamp-right front terminal J
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•
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E4Y turn signal repeater lamp-left terminal 1
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•
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E4LR turn signal lamp-left rear terminal 3
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E4Z turn signal repeater lamp-right terminal 1
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E4RR turn signal lamp-right rear terminal 3
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6.
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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.
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7.
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If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
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8.
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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 K9 BCM.
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9.
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If all circuits test normal, replace the turn signal lamp.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
