GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2009 🢒 Express 🢒 Body Systems 🢒 Lighting 🢒 Turn Signal Lamps and/or Indicators Malfunction

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • 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

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+ - BCM X4 Terminal 1

B2615.00, 5

B2615.00, 5

--

--

B+ - BCM X4 Terminal 2

2

2

--

--

B+ - BCM X4 Terminal 3

7

7

--

--

Left Front Turn Signal Lamp Supply Voltage

2

4

4

--

Right Front Turn Signal Lamp Supply Voltage

B2615.00, 5

5

5

--

Left Rear Stop/Turn Lamp Supply Voltage

2

6

6

--

Right Rear Stop/Turn Lamp Supply Voltage

7

7

7

--

Left Turn Signal Switch Signal

2

2

2*

--

Right Turn Signal Switch Signal

3

3

3*

--

Ground - Turn Signal/Multifunction Switch

--

1

1

--

Ground - LF Park/Turn Signal Lamp

--

4

4

--

Ground - RF Park/Turn Signal Lamp

--

5

5

--

Ground - Left Tail/Stop and Turn Signal Lamp

--

6

6

--

Ground - Right Tail/Stop and Turn Signal Lamp

--

7

7

--

* Internal damage to the turn signal/multifunction switch may occur if shorted to B+

1. All Turn Signals 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

Circuit/System Description

Ground from G303 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 left or right turn position, ground is applied through the respective left or right turn signal switch signal circuit to the body control module (BCM). The BCM then applies a pulsating voltage to the front and rear turn signal lamps through there respective voltage supply circuits. At the same time, the BCM sends a serial data message to the instrument panel cluster (IPC) requesting the respective turn signal indicator be pulsed.

Reference Information

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

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Ignition ON, observe the scan tool Left Turn Signal Switch parameter while using the turn signal/multifunction switch to turn the left turn signal ON and OFF. The reading should change between Active and Inactive.
    2. ⇒If the readings do not change between the specified values, refer to Turn Signal/Multifunction Switch Circuit Test.
  2. Ignition ON, observe the scan tool Right Turn Signal Switch parameter while using the turn signal/multifunction switch to turn the right turn signal ON and OFF. The reading should change between Active and Inactive.
    3. ⇒If the readings do not change between the specified values, refer to Turn Signal/Multifunction Switch Circuit Test.
  3. Command the following turn signals ON and OFF with a scan tool. The respective turn signal should illuminate.
    4. • LF Turn Signal
    • RF Turn Signal
    • LR Turn Signal
    • RR Turn Signal
    ⇒If the turn signal does not illuminate or the outside rearview mirror turn signal does not illuminate, refer to Turn Signal Circuit Malfunction.
  4. With the turn signal/multifunction switch in the left turn position, verify the left turn signal indicator is illuminated on the IPC.
    5. ⇒If the turn signal indicator does not illuminate, refer to Turn Signal Indicators Malfunction.
  5. With the turn signal/multifunction switch in the right turn position, verify the right turn signal indicator is illuminated on the IPC.
    6. ⇒If the turn signal indicator does not illuminate, refer to Turn Signal Indicators Malfunction.

Circuit/System Testing

Turn Signal/Multifunction Switch Circuit Malfunction

  1. Ignition OFF, disconnect the X1 harness connector at the turn signal/multifunction switch.
  2. Verify that a test lamp illuminates between the ground circuit terminal F and B+.
    3. ⇒If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Left Turn Signal Switch parameter is Inactive.
    4. ⇒If not the specified value, test the signal circuit terminal E 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.
    5. ⇒If not the specified value, test the signal circuit terminal D for a short to ground. If the circuit tests normal, replace the BCM.
  5. Connect a 3A fused jumper wire between the signal circuit terminal E and ground. Verify the scan tool Left Turn Signal Switch parameter is Active.
    6. ⇒If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
  6. Connect a 3A fused jumper wire between the signal circuit terminal D and ground. Verify the scan tool Right Turn Signal Switch parameter is Active.
    7. ⇒If not the specified value, test the signal circuit for a short to voltage or and 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 Circuit Malfunction

  1. Ignition OFF, disconnect the X4 harness connect at the BCM.
  2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminals listed below and ground.
    3. • B+ terminal 1
    • B+ terminal 2
    • B+ terminal 3
    ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuits test normal and the circuit fuse is open, test the appropriate control circuit terminal(s) listed below for a short to ground.
    • Terminal 5 X4 for an open BCM 3 fuse
    • Terminal 1 X5 and terminal 4 X5 for an open BCM 5 fuse
    • Terminal 2 X5 for an open BCM 6 fuse
  3. Ignition OFF, disconnect the harness connector at the inoperative turn signal lamp.
  4. Test for less than 5.0 ohms between the appropriate ground circuit terminal listed below and ground.
    5. • Front Turn Signal terminal C
    • Outside Rearview Mirror terminal D
    • Rear Turn Signal terminal G
    ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  5. Connect a test lamp between the appropriate control circuit terminal listed below and ground.
    6. • Front Turn Signal terminal A
    • Outside Rearview Mirror terminal B
    • Rear Turn Signal terminal A
  6. Ignition ON, command the appropriate turn signal ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    7. ⇒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.
  7. If all circuits test normal, test or replace the turn signal bulb.

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.

Component Testing

Turn Signal/Multifunction Switch

  1. Ignition OFF, disconnect the harness connector X1 at the turn signal/multifunction switch.
  2. Test for infinite resistance between the terminals listed below and the ground circuit terminal F with the switch in the neutral position.
    3. • Signal terminal D
    • Signal terminal E
    ⇒If not the specified value, replace the turn signal/multifunction switch.

    Important: If the switch tests open in any switch position other than Off, test the switch signal circuits for a short to voltage before replacing the switch.

  3. Test for less than 2.0 ohms between the signal terminal E and the ground terminal F with the switch in the left turn position.
    4. ⇒If greater than the specified range, replace the turn signal/multifunction switch.
  4. Test for less than 2.0 ohms of resistance between the signal terminal D and the ground circuit terminal F with the switch in the right turn position.
    5. ⇒If greater than the specified range, replace the turn signal/multifunction switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Turn Signal Multifunction Switch Replacement
    •  Parking and Turn Signal Lamp Replacement
    •  Tail Lamp Replacement
    •  Control Module References for BCM and IPC replacement, setup, and programming