Question about 2005 Chevrolet Trailblazer Ext

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Automatic Headlamps Our DRL or automatic lights do not always come on. Our local dealer can not find the problem when running computer diagnostics. They suggest we bring it in when the problem is happening. Of course, the have not given us their home or cell numbers so we can call in the middle of the night when we notice it. Any solution.? glennell@cox.net

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  • Chevrolet Master
  • 1,348 Answers

Dtr module?its been 9 months just wondering if it got fixed.

Posted on May 13, 2009

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2000. Where is fuse for tail lights?


Do your headlamps work ?
Park/Marker/License/Tail Lamps
Voltage is applied to the turn/headlamp switch at all times. When the turn/headlamp switch is in the PARK or the HEAD position, voltage is applied to the following components:
?€¢
The park lamps


?€¢
The marker lamps


?€¢
The tail lamps


?€¢
The license lamp

The front marker lamps are grounded through the turn filament of the respective front park/turn lamp. The front marker lamps light as a result.
The automatic lamp control function turns on the park lamps and the headlamps. This action occurs when the ambient light sensor determines that the exterior lamps should be turned ON based on the amount of available light. When the BCM grounds the park lamp relay, voltage is supplied directly to the park lamps, bypassing the turn/headlamp switch assembly. When this action occurs, the following conditions exist:
?€¢
The automatic lamp control relay is grounded.


?€¢
The headlamps turn ON. Refer to Headlights/Daytime Running Lights (DRL) Circuit Description .

The lamps turn OFF when the BCM does not ground the park lamp relay or the automatic lamp control relay. This action is caused by the following conditions:
?€¢
The available light reaches a predetermined level.


?€¢
The ignition switch is turned to the OFF position

Mar 31, 2016 | Pontiac Grand Am Cars & Trucks

2 Answers

How to turn off the daytime running lights on my 2005 chevy equinox


you have to change daytime running lights module.For now remove cable from battery +

Mar 19, 2016 | Cars & Trucks

1 Answer

No low beam. Good high beam. No day lights. What's wrong?


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.

Feb 23, 2016 | 2005 Chevrolet Equinox LS

1 Answer

Dim head lamps and day light running lamps won't come on my 2000 Buick lasabre


Daytime Running Lamps
With the daytime running lamps (DRL) programmed to be on, the DRL will operate when the ignition switch is in the ON position, the gear selector lever is out of the PARK position, the headlamp switch is in the OFF or PARK position, and the ambient light sensor indicates daytime conditions. Battery positive voltage (B+) is supplied to the DRL relay coil through the underhood fuse block. Battery positive voltage is supplied through the underhood fuse block FOG/DRL Fuse to the DRL relay normally open contact. The DRL relay normally closed contact receives ground for normal high headlamp operation. When the dash integration module (DIM) determines that conditions are right for the DRL, the DIM grounds the DRL relay coil. This energizes the DRL relay coil and closes the switch to the normally open contact. Battery positive voltage (B+) is supplied to the LH and RH high beam headlamps in series. The high beam headlamps split the voltage and each lights at half intensity. Current will follow the path from the DRL relay to the LH high beam headlamp, HDHIBML Fuse, HDHIBMR Fuse, the RH high beam headlamp, then to ground.
Does your vehicle have
Twilight Sentinel
The twilight delay switch in the headlamp switch is supplied a reference voltage from the instrument panel integration module (IPM). It is supplied a reference ground from the IPM. The switch is a potentiometer that resistance varies as the switch is moved. The IPM receives an input voltage proportional to the resistance of the potentiometer. The IPM sends a class 2 message to the dash integration module (DIM) indicating the on/off status and delay length for the twilight sentinel. With the twilight sentinel in an ON position, the DIM will automatically control the headlamps on/off status depending on the nighttime/daytime status of the ambient light sensor. The DIM will use the twilight sentinel delay length to know how long to keep the headlamps and park lamps on after the ignition switch transitions from ON to OFF during nighttime conditions.
If you don't know about these things you best bet is to take it to an ASE certified repair shop or the dealer .
If you
Your best

Nov 30, 2015 | Buick Cars & Trucks

1 Answer

Where is the DRL relay located?


There is no DRL relay , has a lamp control module .
The daytime running lamps (DRL) activate under the following conditions:
?€¢
The ignition switch is in the RUN position.


?€¢
The ambient light sensor indicates daylight.


?€¢
The vehicle is not in the PARK position.

When the above conditions are met, the lamp control module (LCM) supplies battery positive voltage (B+) to the low beam headlamps through CKT 589 (GRY), the DRL resistor, and CKT 12 (TAN). The DRL resistor reduces the voltage supplied by the LCM. The low beam headlamps light at a reduced intensity. The DRL disable if the vehicle is placed in the PARK position. When the ambient light sensor indicates darkness, the low beam headlamps automatically switch from a reduced intensity to a regular intensity.
Lamp Control Module (LCM)
In the center of the IP, below the center heater outlets

Nov 17, 2015 | 1998 Oldsmobile 88

1 Answer

2006 grand Prix the drl stay on and will not go off if they do go off the come back on with nobody around the car keeps running the battery dead ????? Ready to burn it


Daytime Running Lamps (DRL)
The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary between 0.2 and 4.9 volts depending on outside lighting conditions. The body control module (BCM) provides a 5-volt reference signal to the ambient light sensor. The ambient light sensor is permanently grounded at ground G202. The body control module (BCM) monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lights (DRL) or automatic lamp control (ALC) when the headlamp switch is in the AUTO position. In daylight conditions the BCM will command the low beam headlamps ON at reduced intensityy. Any function or condition that turns on the headlamps will cancel DRL operation.
There could be a DTC stored in the BCM pointing to a problem !
DTC B2645 Ambient Light Circuit

2

Turn the headlamp switch to the OFF position.
Do the low and high beam headlamps remain OFF?
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
Go to Step 3

3

Remove the appropriate low or high relay.
Do the lamps turn OFF?
Go to Step 5
Go to Step 4

there could

Oct 26, 2015 | Cars & Trucks

1 Answer

2006 buick allure , automatic low beams do not come on when key starts car


Headlamps
You can use the headlamps two different ways.
?€¢
Place the headlamp switch in the HEAD position for normal operations


?€¢
Place the headlamp switch in the OFF position for automatic lamp control (ALC) operation. During ALC the low beam headlamps are ON for daytime running lamp (DRL) operation in daylight conditions at reduced intensity or low beam headlamps ON at full intensity with exterior park lamps ON in low light conditions. The ambient light sensor is a light-sensitive transistor that varies its voltage signal to the body control module (BCM) in response to changes in the outside (ambient) light level. When the BCM receives this signal the BCM turns ON just the low beam headlamps at reduced intensity for the daytime running lamp (DRL) operation. A resistor wire is used (CKT312) to reduced the voltage which reduces the light intensity for the DRL's function. The ambient light sensor can also turn ON the low beam headlamps and the exterior lamps for automatic lamp control (ALC). Any function or condition that turns ON the headlamps will cancel the DRL operation (this means no reduced voltage to the low beam lights). Thirty seconds after you start the engine with the headlamp switch in the OFF position, the DRL will perform one of two actions:
?€¢
Illuminate the low beam headlamps at reduced intensity in daylight conditions


?€¢
Illuminate the low beam headlamps and exterior park lamps for low light conditions

The DRL operates when the ignition switch is in the RUN position, the parking brake is not set and the transmission is not in the PARK position When these conditions are met and the DRL ambient light sensor indicates daylight conditions the DRL will illuminate
Should have BCM scanned for DTC'S - diagnostic trouble codes , could have DTC'S stored in memory !
DTC B2645 Ambient Light Circuit
The body control module (BCM) monitors the ambient light sensor signal circuit in order to determine if the daytime running lights (DRL) or the auto headlights (ALC) should be turned ON in the AUTO mode. When the BCM senses the ambient light sensor voltage is between 1.75-4.9 volts, either the DRL will be commanded ON or the ALC will be commanded ON.

  1. Turn ON the headlamps.
  2. Ensure that the headlamp dimmer switch is in the LOW position.
Do both low beam headlamps illuminate?
Is only one low beam headlamp inoperative? YES / NO
IF no
  1. Disconnect the lamps switch assembly.
  2. Install a jumper between the headlamp switch headlamps ON signal circuit and ground.
Do the low beam headlamps illuminate?
Do the low beam headlamps illuminate?
Go to Step 18
Go to Step 7

7

  1. Remove the headlamp module.
  2. Install a fused jumper between battery positive voltage and the switched low beam voltage supply circuit.
Do the low beam headlamps illuminate?
Go to Step 8
Go to Step 11

8

Test for the following in the headlamp module control circuit:
?€¢
An open


?€¢
A poor connection


?€¢
A short to ground

Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
Go to Step 19
Go to Step 10

9

Inspect for a poor connection at the harness connector of the lamp switch assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
Go to Step 19
Go to Step 14

10

Inspect for a poor connection at the headlamp module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
Go to Step 19
Go to Step 15

11

Test for a short to ground in the low beam voltage supply circuit. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
Go to Step 19
Go to Step 12

12

Inspect for a poor connection at the harness connector of the underhood fuse block. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
Go to Step 19
Go to Step 17

13

Inspect the inoperative low beam headlamp voltage supply and ground circuit for a high resistance, a short to ground, or an open. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
Go to Step 19
Go to Step 16

14

Replace the lamp switch assembly. Refer to Headlamp Switch Replacement .
Did you complete the replacement?
Go to Step 19
--

15

Replace the headlamp module. Refer to Relay Replacement in Wiring Systems.
Did you complete the replacement?
Go to Step 19
--

16

Replace the inoperative low beam headlamp. Refer to Headlamp Assembly or Headlamp Bulb Replacement .
Did you complete the replacement?
Go to Step 19
--

17

Replace the underhood fuse block. Refer to Testing for Intermittent Conditions and Poor Connections .
Did you complete the replacement?
Go to Step 19
--

18

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?
Go to Step 19
--

19

Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 3

IF

Sep 30, 2015 | Buick Cars & Trucks

1 Answer

Why does my 1999 chevy malibu headlights turn on by them self in middle of night


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:
?€¢
The engine is running.


?€¢
The transaxle is not in the PARK position.


?€¢
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.

May 30, 2015 | 1999 Chevrolet Malibu

1 Answer

No headlights


You need to start by checking the fuse for your headlights (low beams). The DRL could be be bad, but I have not seen them go out very often.

Jun 08, 2009 | 2002 GMC Safari

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