Circuit Description
The Body Control Module (BCM) controls the LF turn signal lamp. The BCM applies power to the LF turn signal lamp which in turns energizes the turn lamp.
Conditions for Running the DTC
The BCM must be commanding the LF turn signal lamp on.
Conditions for Setting the DTC
| • | The BCM detects a short to battery in the LF turn signal lamp circuit. |
| • | The condition above must be present for more than 0.3 seconds. |
Action Taken When the DTC Sets
| • | The BCM stores DTC B2603 in memory. |
| • | The SERVICE VEHICLE SOON telltale illuminates. |
Conditions for Clearing the DTC
| • | A current DTC B2603 will clear if the BCM no longer detects a short to battery in LF turn signal lamp control circuit. |
| • | A history DTC B2603 will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present. |
Diagnostic Aids
| • | If the DTC B2603 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections . |
| • | The following conditions may cause an intermittent malfunction to occur: |
| - | An intermittent short to battery in the LF turn signal lamp control circuit |
| - | The BCM is intermittently shorted to battery internally |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
-
Tests for voltage at the turn signal lamp.
-
Verifies that the Body Control Module is providing B+ to the turn signal lamps.
-
Tests if ground is constantly being applied to the turn signal lamps B+ feed.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Lighting System Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Does the LF turn signal lamp turn ON and OFF with each command? | -- | Go to Diagnostic Aids | Go to Step 3 |
Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 10 | |
Does the test lamp turn ON and OFF with each command? | -- | Go to Step 8 | Go to Step 5 | |
Does the test lamp remain illuminated with each command? | -- | Go to Step 7 | Go to Step 6 | |
6 | Test the control circuit of the LF turn signal lamp for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
7 | Test the control circuit of the LF turn signal lamp for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
8 | Inspect for poor connections at the LF turn signal lamp. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
9 | Inspect for poor connections at the harness connector of the Body Control Module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
10 | Repair the feed circuit of the LF turn signal lamp. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 13 | -- |
11 | Replace the LF turn signal lamp. Refer to Headlamp Assembly or Headlamp Bulb and/or Cornering, Sidemarker, Park, Turn Signal Bulb Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
12 |
Important: Perform the set up procedure for the body control module. Replace the BCM. Refer to Body Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
