Diagnostic Routine B
Diagnostic Routine B
Diagnostic Overview
One Or Both Low Beams Are Inoperative
Refer to Wiring Diagram Set 85 for schematic and connector information Electrical Diagrams.
Normal Operation and Fault Conditions
REFER to Low Beams .
REFER to Headlamp Assembly .
REFER to Ballast .
DTC Fault Trigger Conditions
Visual Inspection and Diagnostic Pre-checks
- Inspect the bulbs and make sure they are OK.
- Inspect the BCM (Body Control Module) fuses 17 (10A) (left low beam) and 16 (10A) (right low beam).
- For HID (High Intensity Discharge) headlamps, inspect the BJB (Battery Junction Box) fuses 57 (20A) (left ballast) and 78 (20A) (right ballast).
- Inspect the headlamp assembly for damage.
Pinpoint Test
NOTE: Due to varying wattage ratings and the resulting current draw differences of certain aftermarket halogen headlamp bulbs, the BCM (Body Control Module) may activate its short circuit protection strategy, resulting in the low beam output circuit becoming inoperative. Verify the bulbs meet Ford specifications. If the bulbs do not meet Ford specifications, install the correct bulbs. Run the on-demand self-test (required to clear certain DTCs (Diagnostic Trouble Codes) and reset the BCM (Body Control Module)). Correct any unresolved DTCs (Diagnostic Trouble Codes). Clear all DTCs (Diagnostic Trouble Codes).
1. CHECK FOR VOLTAGE TO THE HEADLAMP ASSEMBLY
1. Ignition OFF.
2. Disconnect: Inoperative Headlamp.
3. Place the headlamp switch in the headlamps on position.
4. Measure:
Is the voltage greater than 11 volts?
2. CHECK THE HEADLAMP ASSEMBLY GROUND CIRCUIT FOR AN OPEN
1. Measure:
Is the voltage greater than 11 volts?
3. CHECK FOR BALLAST SUPPLY VOLTAGE TO THE HEADLAMP ASSEMBLY
1. Place the headlamp switch in the off position.
2. Measure:
Is the voltage greater than 11 volts?
4. CHECK THE BALLAST
1. Substitute a known good ballast.
2. Place the headlamp switch in the headlamps on position.
Does the inoperative headlamp illuminate?
5. CHECK THE HID (High Intensity Discharge) BULB
1. Place the headlamp switch in the off position.
2. Substitute a known good HID (High Intensity Discharge) bulb.
3. Place the headlamp switch in the headlamps on position.
Does the inoperative headlamp illuminate?
6. REPEAT THE ON-DEMAND SELF-TEST AND CHECK FOR VOLTAGE TO THE HEADLAMP
1. Place the headlamp switch in the off position.
2. Ignition ON.
3. Using a scan tool, clear the DTCs (Diagnostic Trouble Codes) and perform the BCM (Body Control Module) on-demand self-test.
4. Place the headlamp switch in the headlamps on position.
5. Measure:
Is the voltage greater than 11 volts?
7. CHECK THE HEADLAMP HARNESS
1. Ignition OFF.
2. Place the headlamp switch in the off position.
3. Check the headlamp harness for an internal short to the ground circuit.
Is the headlamp harness OK?
8. CHECK THE BCM (Body Control Module) LOW BEAM VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO GROUND
1. Ignition OFF.
2. Place the headlamp switch in the off position.
3. Disconnect: BCM (Body Control Module) C2280E.
4. Measure:
Is the resistance greater than 10,000 ohms?
9. CHECK THE BCM (Body Control Module) LOW BEAM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
1. Measure:
Is the resistance less than 3 ohms?
10. CHECK FOR CORRECT BCM (Body Control Module) OPERATION
1. Disconnect and inspect all BCM (Body Control Module) connectors.
2. Repair:
- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary
3. Reconnect the BCM (Body Control Module) connectors. Make sure they seat and latch correctly.
4. Operate the system and determine if the concern is still present.
Is the concern still present?
