Day time running lamps

If the main beams work, it is unlikely to be a grounds issue, but you could check with a meter from the connector to the vehicle body.

The most likely reasons would be the bulb, the fuse, the relay, or the headlight switch itself.

You very well could have a couple of faulty relays 45 & 46 in the underhood fuse / relay box . Could also have DTC'S - diagnostic trouble code's stored in the BCM - body control module .
DTC B2575 Headlamp Control Circuit
When the body control module (BCM) senses a request for headlamp or daytime running lamp (DRL) illumination, the BCM sends a pulse width modulated (PWM) ground signal to the low beam headlamp driver module through the low beam headlamp driver module control circuit. The low beam headlamp driver module will illuminate the headlamps, adjusting the intensity based on the PWM signal received.
DTC B2585 Park Lamp Control Circuit
When the body control module (BCM) receives a ground signal from the headlamp switch commanding to illuminate the park lamps, the BCM will energize the park lamp relay by grounding the park lamp relay control circuit.
DTC B3802 Park Lamps Request Circuit
The body control module (BCM) monitors the park lamp switch signal circuit and the headlamp switch headlamps on signal circuit in order to determine when the park lamps and headlamps should be illuminated. When the headlamp switch is turned to PARK, the BCM senses that the park lamp switch signal circuit is grounded and the headlamps switch headlamps on signal circuit is open. The BCM will then energize the park lamp relay illuminating the park lamps. When the headlamp switch is turned to HEAD, the BCM senses that the park lamp switch signal circuit and the headlamp switch headlamps on signal circuit are grounded. The BCM will then energize the park lamp relay and headlamp driver module (HDM) illuminating the park lamps and headlamps.
relay # 46 is the HDM headlamp driver module .

There is not a separate fuse nor is there a relay ,A LCM - lamp control module controls the DRL .
the lamp control module (LCM) supplies battery positive voltage (B+) through the DRL resistor to the low beam headlamps. The voltage drop across the DRL resistor causes the low beam headlamps to light at a reduced intensity. The DRL are disabled if the high beam headlamps are on or if the gear selector is placed in the PARK position. When the ambient light sensor indicates darkness, the low beams automatically switch to regular intensity.

Lamp Control Module (LCM) (Oldsmobile)
Under the left side of the IP, to the left of the steering column

Daytime Running Lamps (DRL) Resistor
To the left of the engine compartment, near the underhood fuse block

No on the fuse . The LH HDLP and RH HDLP fuse in the fuse block - under hood, supply battery positive voltage to both low and high beam lamps at all times. For manual operation, when the headlamp switch is in the ON position, the headlamp switch supplies ground directly to the headlamps and to the body control module (BCM) on the headlamp low or high beam signal circuit, depending on the position of the headlamp dimmer switch. The BCM uses this signal to determine if the conditions are present to illuminate the daytime running lamps or park lamps.
The headlamps may be turned on 2 different ways. First, when the driver places the headlamp switch in the ON position, for manual operation. Second, with the headlamp switch placed in the OFF position activating automatic lamp control (ALC).For ALC operation, the BCM receives a signal from the ambient light sensor indicating a low or high ambient, outside, light level. Under low light conditions the BCM grounds the headlamp relay control circuit energizing the headlamp control relay. The now closed relay supplies ground through the headlamp switch to the headlamps and the BCM on the headlamp low or high beam signal circuit, depending on the position of the headlamp dimmer switch. When the BCM grounds the headlamp relay control circuit it also grounds the park lamp relay control circuit illuminating the park lamps. The headlamp relay is grounded at G203.
Daytime Running Lamps (DRL)
The low beam headlamps operate at reduced intensity when in daytime running lamps (DRL) mode. The ground circuit to the switch side of the DRL relay has a resistor in-line to reduce the intensity of the low beam headlamps for DRL operation. The body control module (BCM) receives a signal from the ambient light sensor indicating a low or high ambient, outside, light level. Under daylight conditions the BCM grounds the DRL relay control circuit energizing the DRL control relay. The now closed relay supplies ground directly to the low beam headlamps and to the BCM on the headlamp low beam signal circuit. The low beam headlamps now illuminate with reduced intensity. The DRL relay is grounded at G203. Any time the headlamps are illuminated the DRL will not illuminate. Manual park lamps do not effect DRL operation.

You have a gremlin ! No , just kidding . No it's not the ignition switch ! The headlamps right an left have there own fuse in the under hood fuse box . LH HDLP - RH HDLP . Power direct to the head lamps an they ground through the headlamp switch when placed in high or low beams . Next time they come on wiggle the headlamp switch an see if they go out ! Does your vehicle have auto lights ? Day time running lamps ? The BCM - body control module controls Automatic lamp control !
Battery voltage is applied to the headlamp bulbs at all times. The headlamps are controlled by supplying the ground for the lamps through the turn/headlamp switch assembly or the body control module (BCM). When the turn/headlamp switch is in the ON position, the ground is supplied through CKT 150.
The BCM controls the daytime running lamps (DRL). The system allows the headlamps to operate at a reduced intensity under the following conditions:
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The engine is running.

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The transaxle is not in the PARK position.

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The normal headlamps are turned OFF.

The BCM activates the system by grounding CKT 592. This action energizes the DRL relay. This condition allows a reduced voltage to flow to the headlamps. When the headlamp switch is turned to ON, the headlamps operate normally.
The parking brake provides an input to the BCM. When the parking brake is engaged, the DRL remain disabled until the parking brake is disengaged.

You can't turn them on manually with the switch . You have the switch set on auto ?
Headlamps
You can use the headlamps in two different ways.
• Place the headlamp switch in the ON position for normal operation.
• Place the headlamp switch in the OFF position for automatic lamp control (ALC). During ALC the high beam headlamps are On at reduced intensity for daytime running lamp (DRL) operation in daylight conditions, or low beam headlamps On in low light conditions.
The DRL/EXT LTS fuse and the EXT lamps fuse in the underhood junction block supply battery positive voltage at all times to both of low beam lamps and to the right high beam lamp. The low beam circuit continues to the high/low beam switch, then, depending on the position of the dimmer switch, connects to the normally-open headlamp relay switch contacts. Placing the headlamp switch in the HEAD position provides a ground path for the headlamp switch input of the Body Control Module (BCM). After receiving this input, the BCM energizes the headlamp relay. When the headlamp relay is energized, the low beam circuit is connected to ground G201. The high beam circuit is divided into a left and a right side circuit.
The DRL/EXT LTS fuse in the underhood ignition block supplies battery positive voltage to both the coil and to the normally-closed contact of the DRL relay switch circuit. During high beam operation, the left side current flow is through the closed contacts of the DRL relay, and to the left high beam lamp.
The EXT Lamps fuse in the top of the engine fuse block supplies battery positive voltage to the right high beam lamp. Both high beam circuits are then connected together, and continue to the dimmer switch. When the driver closes the high beam contacts of the dimmer switch, the circuit is grounded at G201.
Both the headlight switch and the BCM provide a ground, or control circuit, to the headlight relay coil circuit for manual or automatic headlamp operation. When you place the headlamp switch in the OFF position, and the ambient light sensor indicates low light conditions, the BCM energizes the headlamp relay for low beam operation. You may switch the headlights to high beam by pulling the dimmer switch handle toward you until the dimmer switch is activated. When the dimmer switch is placed in the HIGH position, the indicator lamp input to the BCM is pulled low. The BCM then sends a class 2 message to the instrument cluster in order to illuminate the high beam indicator lamp.
If the headlamp switch is left in the head position, the inadvertent power control feature will turn off the headlights 10 minutes after you turn the ignition switch to the OFF position. If you place the headlamp switch in the head position after the ignition switch has been turned OFF, or if the ignition switch is in the ACCY position, the headlights will remain ON until you turn them OFF or until the battery runs dead.

it has command start ???? Is this some kind of aftermarket add on ? This shouldn't have anything to do with the running lamps . unless someone hooked something up in correctly . Does the car have DRL - day time running lamps ? The Daytime Running Lamps (DRL) control module is designed to automatically operate exterior lights depending on outside light conditions.
The DRL control module operates in 2 modes:
• The day mode
In the day mode, the DRL control module turns ON the high beam headlamps at a reduced intensity when the DRL ambient light sensor detects daylight under the following conditions:
- The ignition switch is in the RUN position.
- The headlamps are OFF.
- The park brake is OFF (released).
• The low light mode
In the low light mode, the DRL ambient light sensor detects darkness, turning OFF the high beam headlamps and turning ON the low beam headlamps through circuit 10.
Additionally, the DRL ambient light sensor turns ON the following lamps through circuit 9:
- The park lamps
- The sidemarker lamps
- The license lamps
- The tail lamps

I have a 1997 cadillac deville that has both 'daytime running lamps' when put into gear and 'twilight sentinel' which turns the headlamps and parking lamps on at night, and goes off during the day or when it is bright enough.

There is an adjustable delay for the twilight sentinel to turn the headlights off after the ignition key is removed and it is night time.
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I had the 'daytime running lamps' installed on a 1990 Cadillac Deville that turns the headlamps only on when the ignition key is switched to on with an aftermarket module. The headlamps are about 70% or so as bright as the regular twiilight sentinel headlamps and parking lights and are designed to go on during the day.

The twilight sentinel overrides this feature when it gets dark outside.

I had the daytime running lamps installed by an auto electric shop that specializes in electrical systems, alarms, stereos, etc.

Does this help?

Daytime Running Lamps
The daytime running lamp (DRL) system is designed to turn the high beam headlamps on, with a reduced light output, and without illuminating the high beam indicator lamp in the instrument panel. You have a DRL Module.
The multifunction switch is the stalk on your column.

This is 96 F150 circuit. Don't have 94.


Symptom Chart, Headlamps HEADLAMPS Condition Possible Source Action

• Headlamps Inoperative

• Circuitry open/shorted.
• Damaged headlamp switch.
• Blown fuse.

• GO to Pinpoint Test A .

• Headlamps On Continuously

• Circuitry open/shorted.
• Damaged headlamp switch.

• GO to Pinpoint Test B .

• High Beams or Low Beams Inoperative

• Circuitry open/shorted.
• Damaged multi-function switch.

• GO to Pinpoint Test C .

• One High Beam or One Low Beam Headlamp Inoperative

• Circuitry open/shorted.
• Damaged connector.
• Headlamp bulb damaged.

• GO to Pinpoint Test D .

• Flash-to-Pass Inoperative

• Blown fuse.
• Circuitry open/shorted.
• Damaged multi-function switch.

• GO to Pinpoint Test E .