Circuit Description
The BCM provides control for the LH DRL relay circuit. The BCM grounds CKT 1976 in order to energize the LH DRL relay and turn ON the LF turn signal This allows the LF turn signal to be used for DRL, UTD, and approach lighting functions. The BCM monitors the voltage level on CKT 1976. When the BCM commands the relay ON, the voltage level on CKT 1976 should be low. When the relay is OFF, the voltage on CKT 1976 should be high. If the BCM detects a voltage level other than expected, a malfunction is present and a DTC will set.
Conditions for Setting the DTC
| • | The BCM detects a low voltage level (an open or a short to ground) in CKT 1976. |
| • | The BCM can only test for this condition when the BCM is not attempting to energize the LH DRL relay. |
| • | This condition must be present for 2 seconds. |
Action Taken When the DTC Sets
| • | Stores a DTC B0507 in the BCM memory. |
| • | No driver warning message will be displayed for this DTC. |
Conditions for Clearing the DTC
| • | This DTC requires an ignition cycle in order to change from current to history. |
| • | The BCM requests an active LH DRL relay. |
| • | The BCM no longer detects a low voltage level in CKT 1976 only when the BCM is not attempting to energize the LH DRL relay. |
| • | A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present. |
| • | Use the IPC clearing DTCs feature. |
| • | Use a scan tool. |
Diagnostic Aids
| • | The following conditions may cause an intermittent malfunction: |
| - | There is an intermittent open or short to ground in CKT 1976. |
| - | There are poor connections at the BCM, the I/P electrical center, or the LH DRL relay terminals. |
| - | The LH DRL relay is shorted or open internally. |
| • | If CKT 1976 is shorted to ground, the LH DRL will remain ON at all times. If CKT 1976 is open, the LH DRL will remain OFF at all times. |
| • | If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur. Refer to Intermittents and Poor Connections . |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This test determines if there is an open in the underhood electrical center or fuse.
-
This test determines if there is a short to ground in the LH DRL circuit.
-
This test checks the resistance of the LH DRL relay coil.
-
This test checks for an internal LH DRL relay short.
-
This test checks if the BCM can properly control the LH DRL relay by commanding the BCM to ground CKT 1976.
-
This test determines if there is an open in CKT 1976.
-
This test determines if the BCM is causing the short to ground.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Were you sent here from the BCM Diagnostic System Check? | -- | ||
Is the test light ON? | -- | |||
Is the test light ON? | -- | |||
Measure the resistance between the RH DRL relay terminals 1 and 2 (or 85 and 86). Is the resistance within specifications? | 75-105 ohms | |||
Check for continuity between the LH DRL relay terminals 1 and 3 (or 85 and 30). Is there continuity? | -- | |||
Does the test light turn ON and OFF with each command? | -- | |||
Is there continuity? | -- | |||
8 | Check the LH DRL circuit for an intermittent malfunction. Refer to Diagnostic Aids. Was a problem found and repaired? | -- | ||
9 |
Does DTC B0507 set as current? | -- | System OK | |
Is the test light ON? | -- | |||
11 | Locate and repair the short to ground in the I/P electrical center or in CKT 1976. Is the circuit repair complete? | -- | -- | |
12 | Replace the LH DRL relay. Is the replacement complete? | -- | -- | |
13 |
Is the circuit repair complete? | -- | -- | |
14 | Locate and repair the open in the I/P electrical center or in CKT 1976. Is the circuit repair complete? | -- | -- | |
15 |
Is the replacement complete? | -- | -- | |
16 |
Are all DTCs cleared? | -- | -- |
