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 Front Turn Signal Lamp Control
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B3948 02
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B3948 04
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B3948 01
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-
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Right Front Turn Signal Lamp Control
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B3949 02
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B3949 04
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B3949 01
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-
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Left Rear Turn Signal Lamp Control
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B3950 02
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B3950 04
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B3950 01
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-
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Right Rear Turn Signal Lamp Control
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B3951 02
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B3951 04
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B3951 01
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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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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 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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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 Front Turn Signal Lamp Ground
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-
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4
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-
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-
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Right Front Turn Signal Lamp Ground
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-
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5
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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 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. 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 information on diagnostic tools
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Circuit/System Verification
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Ignition ON, observe the diagnostic tool's parameters Right Turn Signal Switch and Left Turn Signal Switch while cycling the S78 Turn Signal/Multifunction Switch between the left and right positions. The readings should toggle between ACTIVE and INACTIVE.
Turn Signal Switch Malfunction
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1.
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Ignition OFF, disconnect the harness connector at the S78 Turn Signal/Multifunction Switch.
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2.
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Verify that a test lamp illuminates between B+ and the ground circuit terminal 3.
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3.
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If the test lamp does not illuminate, test the ground circuit for an open circuit/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 Body Control Module.
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6.
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Verify the scan tool Right Turn Signal Switch parameter is INACTIVE.
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7.
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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 Body Control Module.
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8.
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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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9.
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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 Body Control Module.
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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 Body Control Module.
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12.
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If all circuits test normal, test or replace the S78 Turn Signal/Multifunction 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 inoperative turn signal lamp.
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2.
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Test for less than 5.0 Ω between the appropriate ground circuit terminal listed below and ground.
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•
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E4RF Turn Signal Lamp - Right Front ground circuit harness connector terminal 1
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•
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A9A Outside Rearview Mirror - Driver ground circuit harness connector terminal 4
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•
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E4LF Turn Signal Lamp - Left Front ground circuit harness connector terminal 1
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•
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A9B Outside Rearview Mirror - Passenger ground circuit harness connector terminal 4
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•
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E42L Tail Lamp Assembly - Auxiliary Left ground circuit harness connector terminal F
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•
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E42L Tail Lamp Assembly - Auxiliary Left ground circuit harness connector terminal F
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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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Connect a test lamp between the appropriate control circuit terminal listed below and ground.
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E4RF Turn Signal Lamp - Right Front circuit harness connector terminal 2
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•
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A9A Outside Rearview Mirror - Driver circuit harness connector terminal 16
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E4LF Turn Signal Lamp - Left Front circuit harness connector terminal 2
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•
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A9B Outside Rearview Mirror - Passenger circuit harness connector terminal 16
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•
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E42R Tail Lamp Assembly - Auxiliary Right Turn Signal Lamp circuit harness connector terminal B
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•
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E42L Tail Lamp Assembly - Auxiliary Left Turn Signal Lamp circuit harness connector terminal B
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5.
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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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6.
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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 Body Control Module.
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7.
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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 Body Control Module.
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8.
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If all circuits test normal, replace the appropriate turn signal lamp assembly.
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Turn Signal Indicators Malfunction
Ignition ON, command the All Indicators test ON and OFF with the scan tool, verify both turn signal indicators changes between turn ON and OFF.
Turn Signal Switch
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1.
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Ignition OFF, disconnect the harness connector at the S78 Turn Signal/Multifunction Switch.
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2.
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Test for infinite resistance between the signal circuit terminal 1 and the ground terminal 3.
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3.
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If less than the specified value, replace the S78 Turn Signal/Multifunction Switch.
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4.
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Push the signal/multifunction switch in the turn left position, test for less than 5 Ω between signal terminal 1 and ground terminal 3.
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5.
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If greater than the specified value, replace the S78 Turn Signal/Multifunction Switch.
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6.
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Test for infinite resistance between the signal circuit terminal 7 and the ground terminal 3.
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7.
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If less than the specified value, replace the S78 Turn Signal/Multifunction Switch.
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8.
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Push the signal/multifunction switch in the turn right position, test for less than 5 Ω between signal terminal 7 and ground terminal 3.
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9.
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If greater than the specified value, replace the S78 Turn Signal/Multifunction Switch.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
