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 |
|---|---|---|---|---|
BCM B+ terminal 1 X4 | 2 | 2 | -- | -- |
BCM B+ terminal 2 X4 | B2615 00 | B2615 00 | -- | -- |
BCM B+ terminal 3 X4 | 7 | 7 | -- | -- |
Left Turn Signal Switch Signal | 1, 2 | 2 | 2 | -- |
Right Turn Signal Switch Signal | 1 | 3 | 3 | -- |
Left Front Turn Signal Lamp Control | 2 | 4, 8 | 4 | -- |
Right Front Turn Signal Lamp Control | B2615 00 | 5, 9 | 5 | -- |
Left Rear Stop/Turn Lamp Control | 2 | 6 | 6 | -- |
Right Rear Stop/Turn Lamp Control | 7 | 7 | 7 | -- |
Left Outside Rearview Mirror Turn Signal Lamp Low Reference | -- | 8 | -- | -- |
Right Outside Rearview Mirror Turn Signal Lamp Low Reference | -- | 9 | -- | -- |
LF Park/Turn Signal Lamp Ground | -- | 4 | -- | -- |
RF Park/Turn Signal Lamp Ground | -- | 5 | -- | -- |
Left Tail Stop/Turn Lamp Ground | -- | 6 | -- | -- |
Right Tail Stop/Turn Lamp Ground | -- | 7 | -- | -- |
Turn Signal/Multifunction Switch Ground | -- | 1 | -- | -- |
1. All Turn Signals Inoperative 2. Left Turn Signal Malfunction 3. Right Turn Signal 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 Outside Rearview Mirror Turn Signal Malfunction 9. Right Outside Rearview Mirror Turn Signal Malfunction | ||||
Circuit/System Description
Ground is applied at all times to the turn signal/multifunction switch from G300. The turn signal lamps may only be activated with the ignition switch in the ON position. 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 either the left or right turn position, a ground is applied through the turn signal switch signal circuit to the BCM indicating a turn signal request. When the specific request is seen, the BCM then applies a pulsating voltage through the front and rear turn signal 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.
- 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 parameter should change between Active and Inactive.
- Ignition ON, place the turn signal/multifunction switch in the left turn position. The left turn signal indicator on the IPC should cycle ON and OFF.
- Ignition ON, place the turn signal/multifunction switch in the right turn position. The right turn signal indicator on the IPC should cycle ON and OFF.
| ⇒ | If the parameter does not change between the specified values, refer to Turn Signal/Multifunction Switch Malfunction. |
| ⇒ | If the parameter does change between the specified values and the left turn signal is inoperative, refer to the Turn Signal Malfunction. |
| ⇒ | If the parameter does not change between the specified values, refer to Turn Signal/Multifunction Switch Malfunction. |
| ⇒ | If the parameter does change between the specified values and the right turn signal is inoperative, refer to the Turn Signal Malfunction. |
| ⇒ | If the indicator is always OFF, replace the IPC. |
| ⇒ | If the indicator is always OFF, replace the IPC. |
Circuit/System Testing
Turn Signal/Multifunction Switch Malfunction
- Ignition OFF, disconnect the X3 harness connector at the turn signal/multifunction switch.
- Verify that a test lamp illuminates between the ground circuit terminal G 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 F and the ground circuit terminal G. Verify the scan tool Left Turn Signal Switch parameter is Active.
- Install a 3A fused jumper wire between the signal circuit terminal H and the ground circuit terminal G. 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 F for a short to ground. If the circuit tests normal, replace the BCM. |
| ⇒ | If not the specified value, test the signal circuit terminal H 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 an 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 an open/high resistance. If the circuit tests normal, replace the BCM. |
Turn Signal Circuit Test
- Ignition OFF, disconnect the X4 harness connector at the BCM.
- Ignition ON, verify that a test lamp illuminates between the following B+ terminals and ground.
- Ignition OFF, disconnect the harness connector at the inoperative turn signal lamp.
- Test for less than 5 ohms between the ground circuit terminal G and ground.
- Connect a test lamp between the control circuit terminal A and the ground circuit terminal G.
- Ignition ON, command the inoperative 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 appropriate turn signal lamp assembly.
| • | B+ terminal 1 |
| • | B+ terminal 2 |
| • | B+ terminal 3 |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. |
| ⇒ | If greater than the specified range, 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. |
Outside Rearview Mirror Turn Signal Circuit Test
- Ignition OFF, disconnect the X1 harness connector at the inoperative outside rearview mirror.
- Connect a test lamp between the low reference circuit terminal 2 and B+.
- Ignition ON, command the appropriate LF or RF Turn Signal ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- Connect a test lamp between the control circuit terminal 1 and ground.
- Command the appropriate LF or RF 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 outside rearview mirror lamp.
| ⇒ | If the test lamp is always ON, test the low reference circuit for a short to ground. If the circuit tests normal, replace the door module. |
| ⇒ | If the test lamp is always OFF, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the door module. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. |
| ⇒ | If the test lamp is always OFF, test the control circuit for an open/high resistance. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM, IPC, and door control module replacement, setup, and programming |
