Circuit Description
Ground is applied to the turn signal switch. When the turn signal switch is placed in the turn left position, ground is applied to the BCM through the left turn signal switch circuit. The BCM then applies a pulsating voltage to the LF and LR turn signal lamps through the LF and LR turn signal voltage supply circuits.
Conditions for Running the DTC
The battery voltage must be between 9.0-14 volts.
Conditions for Setting the DTC
| • | DTC B3948 02 A short to ground in the LF turn signal voltage supply circuit is present for longer than 0.1 seconds. |
| • | DTC B3948 05 A short to battery positive voltage or an open is detected in the LF turn signal voltage supply circuit is present for longer than 1 second. |
Action Taken When the DTC Sets
| • | If DTC B3948 02 sets, the left front turn signal lamp does not work. |
| • | If DTC B3948 05 sets, if the LF turn signal voltage supply circuit is shorted to battery positive voltage the left front turn signal lamp will be on at all times and if the LF turn signal voltage supply circuit is open the left front turn signal lamp will be inoperative. |
Conditions for Clearing the DTC
| • | The DTC will clear on current status after the condition for setting the fault is corrected. |
| • | DTC B3948 will set a history code which will clear after 100 consecutive ignition cycles without a fault present. |
Diagnostic Aids
| • | Check the LF turn lamp bulb. If the bulb is open, DTC B3948 05 will be set. |
| • | If the DTC is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | An intermittent short to ground or an open in the following locations may cause an intermittent malfunction to occur: |
| - | The BCM |
| - | The underhood electrical center |
| - | The left front turn signal supply voltage circuit |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Exterior Lights Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems | |||
1 | Did you perform the Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Do the front left turn signal lamps flash ON and OFF? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
3 | Is DTC B3948 02 set? | Go to Step 4 | Go to Step 6 |
4 |
Does the test lamp illuminate? | Go to Step 5 | Go to Step 12 |
5 | Test the LF turn signal voltage supply circuit for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 11 |
6 | Is the LF turn signal lamp on at all times? | Go to Step 7 | Go to Step 9 |
7 | Disconnect the BCM harness connector C1. Does the LF turn lamp turn OFF? | Go to Step 12 | Go to Step 8 |
8 | Test for a short to battery positive voltage in the LF turn signal lamp voltage supply circuit. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 11 |
9 |
Did you find and correct the condition? | Go to Step 15 | Go to Step 10 |
10 |
Did you find and correct the condition? | Go to Step 15 | Go to Step 11 |
11 | Inspect for a high resistance or an open at the harness connector of the underhood electrical center. 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 15 | Go to Step 13 |
12 | Inspect for a high resistance or an open at the harness connector of the BCM. 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 15 | Go to Step 14 |
13 | Replace the underhood electrical center. Refer to Underhood Electrical Center or Junction Block Replacement in Wiring Systems. Did you complete the replacement? | Go to Step 15 | -- |
14 |
Important: After replacing the BCM, perform the setup procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration in Computer/Integrating Systems. Replace the BCM. Refer to Body Control Module Replacement in Computer/Integrating Systems. Did you complete the replacement? | Go to Step 15 | -- |
15 |
Does the DTC reset? | Go to Step 2 | System OK |
