Pinpoint Test D: The Low Beam(s) Are Always On
Headlamps
Pinpoint Test D: The Low Beam(s) Are Always On
Refer to Wiring Diagram Set 85, Headlamps/Autolamps for schematic and connector information. [1][2]Diagrams By Number
Normal Operation
The Smart Junction Box (SJB) sends voltage signals to the headlamp switch through individual circuits (OFF, PARKING LAMPS and HEADLAMPS). At any given time, the headlamp switch routes one of the input circuits to ground.
When the SJB (Smart Junction Box) detects the headlamp switch in the HEADLAMPS ON position (or a fault with one of the headlamp switch input circuits for more than 5 seconds) and the multifunction switch in the LOW BEAM position, the SJB (Smart Junction Box) provides voltage to the headlamps.
For MKZ equipped with High Intensity Discharge (HID) headlamps, a relay is utilized to provide voltage for the low beam headlamps.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Headlamp relay
- Headlamp switch
- SJB (Smart Junction Box)
PINPOINT TEST D : THE LOW BEAM(S) ARE ALWAYS ON
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
D1 CHECK FOR AUTOLAMP DTCs
- Review the DTCs retrieved from the SJB (Smart Junction Box) self-test.
Is DTC B1696, B1791, B1793 or B2008 present?
Yes
REFER to Autolamps Special Tool(s) Used With Diagnostics.
No
If equipped with autolamps, GO to D2.
If not equipped with autolamps, GO to D3.
D2 CHECK THE SJB (Smart Junction Box) AUTOLAMP ON REQUEST PID
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB (Smart Junction Box) DataLogger.
- While placing the headlamp switch in the AUTOLAMPS ON and then OFF position, monitor the SJB (Smart Junction Box) headlamp switch PID (HDLMP_AUT_CKT).
Does the PID indicate ON with the headlamp switch in the AUTOLAMPS ON position and OFF when the headlamp switch is in the OFF position?
Yes
GO to D3.
No
GO to Pinpoint Test H Pinpoint Test H: The Autolamps Are On Continuously.
D3 CHECK THE SJB (Smart Junction Box) HEADLAMP SWITCH PIDs
NOTE: Make sure the headlamp switch is lined up in the correct position when monitoring the PIDs.
- Enter the following diagnostic mode on the scan tool: SJB (Smart Junction Box) DataLogger.
- NOTE: Only one PID should indicate ON at each headlamp switch position.
While moving the headlamp switch through all positions, monitor the SJB (Smart Junction Box) headlamp switch input PIDs (HDLMP_OFF_CKT, HDLMP_PRK_CKT, HDLMP_ON_CKT).
Do the headlamp switch positions agree with the PIDs (with only one PID indicating ON in each position)?
Yes
GO to D8.
No
GO to D4.
D4 CHECK FOR VOLTAGE SIGNALS TO THE HEADLAMP SWITCH
- Ignition OFF.
- Disconnect: Headlamp Switch C205.
- Measure the voltage between the headlamp switch, harness side and ground as follows:
Headlamp Switch Connector-Pin Circuit C205-6 CLF23 (WH/VT) C205-2 CLS34 (GY) C205-7 CLF18 (BU/WH)
Are the voltages greater than 10 volts?
Yes
GO to D5.
No
GO to D6.
D5 CHECK FOR VOLTAGE TO THE HEADLAMP SWITCH USING THE CONNECTOR GROUND
- Measure the voltage between the headlamp switch C205-6, circuit CLF23 (WH/VT), harness side and the headlamp switch C205-3, circuit GD116 (BK/VT), harness side.
Is the voltage greater than 10 volts?
Yes
INSTALL a new headlamp switch. REFER to Headlamp Switch . TEST the system for normal operation.
No
REPAIR circuit GD116 (BK/VT) for an open. TEST the system for normal operation.
D6 CHECK THE HEADLAMP SWITCH INPUT CIRCUITS FOR A SHORT TO GROUND
- Disconnect: SJB (Smart Junction Box) C2280B.
- Measure the resistance between the headlamp switch, harness side and ground as follows:
Headlamp Switch Connector-Pin Circuit C205-6 CLF23 (WH/VT) C205-2 CLS34 (GY) C205-7 CLF18 (BU/WH)
Are the resistances greater than 10,000 ohms?
Yes
GO to D7.
No
REPAIR the circuit in question for a short to ground. TEST the system for normal operation.
D7 CHECK THE HEADLAMP SWITCH INPUT CIRCUITS FOR AN OPEN
- Measure the resistance between the headlamp switch, harness side and the SJB (Smart Junction Box) , harness side as follows:
Headlamp Switch Connector-Pin SJB (Smart Junction Box) Connector-Pin Circuit C205-6 C2280B-47 CLF23 (WH/VT) C205-2 C2280B-31 CLF34 (YE/OG) C205-7 C2280B-30 CLF18 (BU/WH)
Are the resistances less than 5 ohms?
Yes
GO to D11.
No
REPAIR the circuit in question for an open. TEST the system for normal operation.
D8 CHECK THE SJB (Smart Junction Box) OUTPUT
- Disconnect: SJB (Smart Junction Box) C2280E.
Does the LH or RH headlamp continue to illuminate?
Yes
For MKZ with halogen headlamps or Fusion, REPAIR circuit CLF04 (BN/BU) (LH headlamp) or circuit CLF05 (BU/GN) (RH headlamp) for a short to voltage. TEST the system for normal operation.
For MKZ with HID (High Intensity Discharge) headlamps, GO to D9.
No
GO to D11.
D9 CHECK THE HEADLAMP RELAY OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: Suspect Headlamp Relay.
Does the LH or RH headlamp continue to illuminate?
Yes
REPAIR circuit CLF30 (VT/BN) (LH headlamp) or circuit CLF31 (YE/GY) (RH headlamp) for a short to voltage. TEST the system for normal operation.
No
GO to D10.
D10 CHECK HEADLAMP RELAY
- Substitute a known good relay.
Does the LH or RH headlamp continue to illuminate?
Yes
REPAIR circuit CLF04 (BN/BU) (LH headlamp) or circuit CLF05 (BU/GN) (RH headlamp) for a short to voltage. TEST the system for normal operation.
No
REMOVE the known good relay. INSTALL a new headlamp relay. TEST the system for normal operation.
D11 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION
- Disconnect all the SJB (Smart Junction Box) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB (Smart Junction Box) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new SJB (Smart Junction Box). TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.