B0503

CIRCUIT DESCRIPTION
The BCM provides control for the RH DRL relay circuit. The BCM grounds the RH DRL relay control circuit 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 the RH DRL relay control circuit. When the BCM commands the relay ON, the voltage level on the RH DRL relay control circuit should be low. When the relay is OFF, the voltage on the RH DRL relay control circuit 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 the RH DRL relay control circuit.
^ The BCM can only test for this condition with the RH DRL relay energized.
^ This condition must be present for 2 seconds.

ACTION TAKEN WHEN THE DTC SETS
Stores a DTC B0503 in the BCM memory.

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 high voltage level in the RH DRL relay control circuit only with the RH DRL relay 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.
^ The BCM receives the Clear Code command from the scan tool.

DIAGNOSTIC AIDS
^ The following conditions may cause an intermittent malfunction:
- There is an intermittent open or short to voltage in the RH DRL relay control circuit.
- There is low resistance in the relay coil.
- There are poor connections at the BCM, the I/P fuse block, or the RH DRL relay terminals.
- The RH DRL relay is shorted to voltage internally.
^ If the BCM is open internally, or if the RH DRL relay control circuit is shorted to voltage, 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 Testing for Intermittent and Poor Connections in Diagnostic Aids.

TEST DESCRIPTION

Steps 1-2:

Steps 3-13:

The number(s) below refer to the step number(s) on the diagnostic table.
2. Listen for an audible click when the RH DRL relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
3. Tests for voltage at the coil side of the RH DRL relay. The APPROACH fuse supplies power to the coil side of the RH DRL relay.
4. Verifies that the BCM is providing ground to the RH DRL relay.
5. Tests if ground is constantly being applied to the RH DRL relay.
6. Tests for a short to voltage in the RH DRL control circuit.