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Home >> Mercury >> 2009 >> Mariner Base, 2.5 7, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 31 (Exterior Lighting System) >> Diagnostic Tests >> Headlamps >> Pinpoint Tests >> Pinpoint Test F: The Headlamps Are On Continuously >> Normal Operation

Normal Operation

WARNING: This page is about a different car, the 2009 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

The smart junction box (SJB) sends voltage reference signals to the headlamp switch through circuits 1400 (TN/WH), 1401 (BK/LG), and 1402 (RD/WH). At any given time, the headlamp switch routes one of the input circuits to ground through circuit 1205 (BK).

When the SJB detects the headlamp switch in the HEADLAMPS ON position (or a fault with the headlamp switch inputs) and the multifunction switch in the LOW BEAM position, the SJB sends voltage through circuits 1338 (WH) and 1336 (LG/WH) to the LH and RH low beams, or the LH and RH high intensity discharge (HID) relays (if equipped), respectively.

When the HID relays are energized, voltage is routed to the LH and RH headlamps through circuits 2008 (PK/BK) and 2009 (PK/WH), respectively.

The SJB also sends a voltage reference signal to the multifunction switch through circuits 1394 (WH/RD) and 1395 (RD/PK). When the multifunction switch is placed in the FLASH-TO-PASS or HIGH BEAM position, the signal is routed back to the SJB (ground internal to the SJB). When the SJB detects a request for flash-to-pass or high beams, the SJB provides ground to the high beam relay through circuit 1708 (LG/BK). When the high beam relay is energized, voltage is routed through circuits 1337 (VT/YE) and 1335 (YE/WH) to the LH and RH headlamps, respectively.

DTC Description Fault Trigger Conditions
B1470 - Lamp Headlamp Input Circuit Failure A continuous and on-demand DTC that sets when the SJB detects an unexpected or conflicting value from the headlamp switch input circuits, such as an open or short to ground.
B2501 - LF Lamp Low Beam Circuit Failure A continuous and on-demand DTC that sets when the SJB detects a short to voltage from the LH headlamp voltage supply circuit.
B2503 - RF Lamp Low Beam Circuit Failure A continuous and on-demand DTC that sets when the SJB detects a short to voltage from the RH headlamp voltage supply circuit.
B2586 - Headlamp Mode Select Circuit Failure An on-demand DTC that sets when the SJB detects a short to ground from either of the multifunction switch input circuits.
B2598 - Headlamp Relay Circuit Failure A continuous and on-demand DTC that sets when the SJB detects a short to ground from the high beam relay coil ground controlled circuit.

This pinpoint test is intended to diagnose the following:

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