Circuit Description
The BCM provides control for the RH DRL relay circuit. The BCM grounds CKT 1966 in order to energize the RH DRL relay and turn ON the RF turn signal. This allows the RF turn signal to be used for DRL, UTD, and approach lighting functions. The BCM monitors the voltage level on CKT 1966. When the BCM commands the relay ON, the voltage level on CKT 1966 should be low. When the relay is OFF, the voltage on CKT 1966 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 1966. |
| • | The BCM can only test for this condition with the RH DRL relay de-energized. |
| • | This condition must be present for 2 seconds. |
Action Taken When the DTC Sets
| • | Stores a DTC B0502 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 no longer detects a low voltage level in CKT 1966 only with the RH DRL relay de-energized. |
| • | 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 1966. |
| - | There is high resistance in the relay coil. |
| - | There are poor connections at the BCM, the I/P electrical center, or the RH DRL relay terminals. |
| - | The RH DRL relay is shorted or open internally. |
| • | If CKT 1966 is shorted to ground, the RH DRL will remain ON at all times and the RH turn signal will not flash. If CKT 1966 is open, the RH DRL will remain OFF at all times, but the RH turn signal will still function normally. |
| • | 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 RH DRL control circuit.
-
This test checks the resistance of the RH DRL relay coil.
-
This test checks for an internal short in the RH DRL relay.
-
This test checks if the BCM can properly control the RH DRL relay by using a scan tool to command the BCM to ground CKT 1966.
-
This test determines if there is an open in CKT 1966.
-
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 of the RH DRL relay coil between terminals 1 and 2 (or 85 and 86). Is the resistance within specifications? | 75-105 ohms | |||
Check for continuity between the RH 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 RH DRL circuit for an intermittent malfunction. Refer to Diagnostic Aids. Was a problem found and repaired? | -- | ||
9 |
Does DTC B0502 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 1966. Is the circuit repair complete? | -- | -- | |
12 | Replace the RH 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 1966. Is the circuit repair complete? | -- | -- | |
15 |
Is the replacement complete? | -- | -- | |
16 |
Is the repair complete? | -- | -- |
