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 high voltage level (a short to voltage or BCM open internally) in CKT 1966. |
| • | The BCM can only test for this condition when the BCM is not attempting to energize the RH DRL relay. |
| • | This condition must be present for 2 seconds. |
Action Taken When the DTC Sets
| • | Stores a DTC B0503 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 requests an active RH DRL relay. |
| • | The BCM no longer detects a high voltage level in CKT 1966 only when the BCM is attempting to energize the RH 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 voltage in CKT 1966. |
| - | There are poor connections at the BCM, the I/P electrical center, or the RH DRL relay terminals. |
| - | The RH DRL relay is shorted to voltage internally. |
| • | If the BCM is open internally, or if CKT 1966 is shorted to voltage, the RH 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 a short to voltage in the RH DRL circuit.
-
This test checks the resistance of the RH DRL relay coil.
-
This test checks if the BCM can properly control the RH DRL relay by commanding 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 voltage.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Were you sent here from the BCM Diagnostic System Check? | -- | ||
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 | |||
Does the test light turn ON and OFF with each command? | ||||
Is there continuity? | -- | |||
6 | Check the RH DRL circuit for an intermittent malfunction. Refer to Diagnostic Aids. Was a problem found and repaired? | -- | ||
7 |
Does DTC B0503 set as current? | -- | System OK | |
Is the test light ON? | -- | |||
9 | Locate and repair the open in the I/P electrical center or in CKT 1966. Is the circuit repair complete? | -- | -- | |
10 | Locate and repair the short to voltage in the I/P electrical center or in CKT 1966. Is the circuit repair complete? | -- | -- | |
11 | Replace the RH DRL relay. Is the replacement complete? | -- | -- | |
12 |
Is the replacement complete? | -- | -- | |
13 |
Are all DTCs cleared? | -- | -- |
