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 | 2 | 2 | -- | -- |
B+, BCM X4 terminal 2 | B2615 00, 5 | B2615 00, 5 | -- | -- |
B+, BCM X4 terminal 3 | 7 | 7 | -- | -- |
Left Turn Signal Switch Signal | 2 | 2 | 2 | -- |
Right Turn Signal Switch Signal | 3 | 3 | 3 | -- |
Left Front Turn Signal Lamp Control | 4 | 4 | 4 | -- |
Right Front Turn Signal Lamp Control | 5 | 5 | 5 | -- |
Left Rear Stop/Turn Lamp Control | 6 | 6 | 6 | -- |
Right Rear Stop/Turn Lamp Control | 7 | 7 | 7 | -- |
Ground - Turn Signal/Multifunction Switch | -- | 1 | -- | -- |
Ground - LF Park/Turn Signal Lamp | -- | 4 | -- | -- |
Ground - RF Park/Turn Signal Lamp | -- | 5 | -- | -- |
Ground - Left Tail/Stop and Turn Signal Lamp | -- | 6 | -- | -- |
Ground - Right Tail/Stop and Turn Signal Lamp | -- | 7 | -- | -- |
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 stop/turn signal malfunction 7. Right rear stop/turn signal malfunction | ||||
Circuit/System Description
The body control module (BCM) controls the vehicle turn signals based on inputs from the turn signal/multifunction switch. With the turn signal/multifunction switch in the left turn position, a ground path is provided on the left turn signal switch signal circuit, indicating a left turn signal request. With the turn signal/multifunction switch in the right turn position, a ground path is provided on the right turn signal switch signal circuit, indicating a right turn signal request. When the specific request is seen, the BCM will pulse the respective turn signal lamp supply voltage circuits, illuminating the turn signal lamps.
When a turn signal request is seen by the BCM, a serial data message is sent to the instrument panel cluster (IPC) requesting the respective turn signal indicator be pulsed.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- 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 parameter should change between Active and Inactive.
- View 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 parameter should change between Active and Inactive.
- Command the turn signals listed below ON and OFF with a scan tool. The respective turn signal should turn ON and OFF when changing between the commanded states.
- With the turn signal/multifunction switch in the left turn position, verify the left turn signal indicator is illuminated on the IPC.
- With the turn signal/multifunction switch in the right turn position, verify the right turn signal indicator is illuminated on the IPC.
| ⇒ | If the parameter does not change between the specified values, refer to Turn Signal/Multifunction Switch Circuit Test. |
| ⇒ | If the parameter does not change between the specified values, refer to Turn Signal/Multifunction Switch Circuit Test. |
| • | LF Turn Signal |
| • | RF Turn Signal |
| • | LR Turn Signal |
| • | RR Turn Signal |
| ⇒ | If the turn signal does not turn ON and OFF as specified, refer to Turn Signal Circuit Test. |
| ⇒ | If the turn signal indicator does not illuminate, refer to Turn Signal Indicators Malfunction. |
| ⇒ | If the turn signal indicator does not illuminate, refer to Turn Signal Indicators Malfunction. |
Circuit/System Testing
Turn Signal/Multifunction Switch Circuit Test
- Ignition OFF, disconnect the harness connector X1 at the turn signal/multifunction switch.
- Verify that a test lamp illuminates between the ground circuit terminal E and B+.
- Ignition ON, verify the scan tool Left Turn Signal Switch parameter is Inactive.
- Verify the scan tool Right Turn Signal Switch parameter is Inactive.
- Install a 3A fused jumper wire between the signal circuit terminal D and the ground circuit terminal E. Verify the scan tool Left Turn Signal Switch parameter is Active.
- Install a 3A fused jumper wire between the signal circuit terminal F and the ground circuit terminal E. Verify the scan tool Right Turn Signal Switch parameter is Active.
- If all circuits test normal, test or replace the turn signal/multifunction switch.
| ⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance. |
| ⇒ | If not the specified value, test the signal circuit terminal D for a short to ground. If the circuit tests normal, replace the BCM. |
| ⇒ | If not the specified value, test the signal circuit terminal F for a short to ground. If the circuit tests normal, replace the BCM. |
| ⇒ | 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. |
| ⇒ | 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. |
Turn Signal Circuit Test
- Ignition OFF, disconnect the harness connect X4 at the BCM.
- Ignition ON, verify a test lamp illuminates between the B+ circuits listed below and ground.
- Ignition OFF, disconnect the harness connector at the inoperative turn signal lamp.
- Verify that a test lamp illuminates between the ground circuit terminal G and B+.
- Connect a test lamp between the control circuit terminal A and the ground circuit terminal G.
- 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.
- If all circuits test normal, test or replace the turn signal lamp.
| • | 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 circuit tests normal and the fuse is open, test the appropriate control circuit(s) listed below for a short to ground. |
| • | LT T/SIG Fuse - terminal 1 X5 and terminal 4 X5 |
| • | RT T/SIG Fuse - terminal 2 X5 |
| • | INT LIGHTS Fuse - terminal 5 X4 |
| ⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance. |
| ⇒ | 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. |
Turn Signal Indicators Malfunction
Ignition ON, while observing the turn signal lamp indicators, with a scan tool perform the Display Test for the instrument panel cluster (IPC). The left and right turn signal indicators should illuminate.
| ⇒ | 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
- Ignition OFF, disconnect the X1 harness connector at the turn signal/multifunction switch.
- Test for infinite resistance between the signal terminals listed below and the ground circuit terminal E with the switch in the neutral position.
- Test for less than 2.0 ohms between the signal terminal D and the ground terminal E with the switch in the left turn position.
- Test for less than 2.0 ohms between the signal terminal F and the ground terminal E with the switch in the left turn position.
| • | Signal terminal D |
| • | Signal terminal F |
| ⇒ | 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.
| ⇒ | If greater than the specified range, replace the turn signal/multifunction switch. |
| ⇒ | If greater than the specified range, replace the turn signal/multifunction switch. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM and IPC replacement, setup, and programming |
