Wednesday, June 15, 2011

when DRL lights are turned on most of the dash-lights including the clock turn off completely on 2000 chevy astro?

THE DRL light turning on this turns on headlight but other lights shuts off.-------------For this problem read as follows:---


It is in RELAY BLOCK # 2, hidden just above the DTC connector.

There are 2 relays in the block, the DRL and the RAP -which controls the items that are powered after the key is shut off. Radio and windows work until a door is opened or 20 minutes goes by.

The relay block is held onto a plastic bracket with 2 plastic rivets I guess they would be called. They are hollow with a plastic peg that when pushed in expands them.

I pried the relay block off the bracket as it is not possible to pull the relays when it is in situ as they are mounted from the top.

There is a cover over the relays for no apparent reason beyond making it more difficult to find them?

Anyway, after I got the relay block out, pulled the relay and bent over the 87 pin as mentioned in your info for various GM vehicles. Fixed, no more DRL and all lights working.

Pushed the centers out of the mounting rivets and replaced relay block in position, inserted expander pegs into rivets and done.-------------------------

SECOND trick:---
It's as simple as pulling out the 20A fuse in position #15 (labelled "DRL") in the underdash fuse block, which is on the driver's side under a black plastic cover.
Third trick BUT only for
2005 Chevy Astro and Safari

Remove the plastic cover from the B pillar behind the driver's seat (or just loosen it enough to swing the bottom outward) and unplug the large diode used to drop the voltage.

To disable Automatic Headlights (which also turn on the dash lights and all the other exterior lights), pull the center defroster grill out, unplug the sensor and insert a 2k ohm resistor into the plug (cover it with tape so the leads cannot short to anything metallic under the dash). This fools the computer into thinking that it is a bright sunny day outside. Leave the sensor where it is, replace the grill, and you're done.


Many GM have a "DRL fuse", associated with a DRL Module & and up to 3 relays. Usually HI beams in series. Some the LO beams are reduced by 2 volts with a double diode assembly. Some, the fuse also controls the Fog lights and "automatic lights on" at dusk feature. Other cars the fuse will not deactivate the fogs and auto "ON". 1999 and 2000 more likely to have the "auto on" feature, related to the GM liability for no tail lights at night.

On some newer GM models it may be possible to press the "Dome Override" button 3 or 4 times within 6 seconds. This will disable the DRLs while the vehicle is running. When it is restarted, the DRL function will reset to "always on." We've heard that this works on full-size and S-series trucks.

I believe most recent GM models (99+), use a VCR tape sized DRL module that will be under the dash, behind radio, glovebox, over pedals, etc. There are two 8 pin connectors, the smaller blue connector C2; A is GND, B is NC, (jump A to B to disable) or pin C (pink) is ignition power, if fused separately, just remove fuse or disconnect power wire. Failing to find the module, there is a headlamp relay (5 pins) located in the engine compartment or near the steering column, and if you bend over one of the coil pins, #85 or #86, or the normally open contact #87, that will disable the DRL. (#30 and #87a are needed)

GM cars that I have seen, the DRL has a switch at the parking brake. To defeat DRLs while driving, simply a jumper at switch. (Note, this may illuminate the BRAKE light on your dashboard, making brake system failures unreportable!).
UPDATE: As of 2003, GM cars now sense when parking brake is set and the vehicle is moving more than 3 mph. If both are true, DRL's are turned on automatically.


Here are some details on how I disabled the DRL and automatic headlights on 2000 SS #670.

The DRL module (or whatever it's called -- it does a lot more than just manage the DRLs) is in the center console behind the radio.

Step one is to disconnect the negative terminal of the battery.

Camaro consoleTrim removed

To gain access to the DRL module, first remove the console trim. Gently pry it forward with your fingers; it should pop out easily. It's easier in the long run to disconnect the fog lamp and ASR switch connectors. To do this you'll need a screw driver or similar tool to hold the connector release down.

Radio removedDRL module

Next use a 7mm nut driver to remove the two radio fasteners. Move the radio forward and down out of the way. Be careful not to scratch the radio or the console. The DRL module is a bit to the right. To remove it, gently pull up and disengage it from its plastic mount. There is enough slack in the wiring harness to bring it out of the console.

DRL connectorsJumper detail

The DRL module has two connectors. Connector C1 is a black 8 cavity connector that is mostly outputs; connector C2 is a blue 8 cavity connector that is mostly inputs. C2 is smaller than C1.

DRL connector C1DRL connector C2

Carefully take the module apart. The C2 connector (blue) only has 7 of the 8 cavities used. A is a black wire and is ground and C is a pink wire and hot (you can verify this with a DVM). B is the disable line and should not have a wire in its cavity.

To disable the DRL module, solder a small wire between the A and B conductors of connector C2 on the back of the DRL module PC board.

Put everything back together, reconnect the battery and test. Your headlights should only come on when you turn on the dash board headlight switch.

Can I just remove the DRL connector?

Yes, removing the C2 connector will disable DRL and automatic headlights. It also prevents the ebrake switch from turning on the "BRAKE" light on your instrument cluster. And with a manual transmission, it disables the power hatch release.

Removing the C1 connector will disable DRL and automatic headlights. However it also disables the front turn signal lights.

Disable automatic headlights only

If you like daytime running lights and only want to disable the automatic headlights feature, you can achieve this by replacing the ambient light sensor (really a photo-resistor) with a wire. According to the wiring diagram in the factory service manual (see images below), this is how the Pontiac F-Body (which does not have automatic headlights) is wired.

[Chevrolet ambient light sensor wiring][Pontiac ambient light sensor wiring]
Chevrolet ambient light sensor wiringPontiac ambient light sensor wiring

The ambient light sensor is located directly above the DRL module on the dashboard. You can gain access to it either by removing the radio or by lifting the upper trim pad. The sensor has a connector on it. Just stuff a short piece of wire in place of the sensor and then heat shrink or tape up it to avoid shorts.

[DRL ambient light sensor]
DRL ambient light sensor

I've been told that this trick (replacing the ambient light sensor with a wire) also works on a 1999 Pontiac Grand Am.


The Daytime Running Lamps (DRL) lights are controlled by the Body Control Module (BCM) via the DRL relay when the headlamp and panel dimmer switch is the AUTO position.

The vehicle is also equipped with automatic headlamps, which is activated when the photo sensor detects dark conditions. A code will set if there is a fault in the photo sensor, or in the two CKT's between the photo sensor and the body control module (BCM).

The DRL relay is fed by the gauges fuse through CKT 39 (PNK) when the ignition switch is in the run and crank position, (the coil side of the relay), and the Gauges fuse. The DRL relay is controlled by the BCM based on the input form the ambient light sensor via CKT 592 (LT GRN/BLK).

The relay supplies a ground path to the lights through CKT 544 (PPL) and through CKT 750 (BLK).

The DRL lights are on when the vehicle ignition switch is in the run position, and the park brake is not set, daylight conditions exists and the transmission has been in drive before placing in park. The DRL lights are turned off when the headlamp and panel dimmer switch is turned to the park or head position or the input to the BCM from the ambient light sensor signals that daylight conditions do not exist any more.

The DRL headlamps can be disabled by pressing the dome lamp override switch four times within a six second period. This will disable the DRL headlamps until the ignition is turned OFF. The DRL headlamps will return to normal operation when the ignition is recycled.


Voltage is available to the headlamp and panel dimmer switch at all times. When the headlamp and panel dimmer switch is activated, the two following actions occur via CKT 352 (WHT):

  • A head lamp enable request is sent to the body control module (BCM)
  • The headlamp relay is activated

The VE1 option is equipped with automatic headlamps, which is activated when the photo sensor detects dark conditions. A code will set if there is a fault in the photo sensor, or in the two CKT's between the photo sensor and the Body Control Module (BCM) .

The coil output of the headlamp relay travels through CKT250 (BLK) and is grounded at G1O1.

When the headlamp relay is activated, power is supplied to both the LH and RH head lamp fuses through CKT 1346 (LT BLU).

LO and HI beam functions are activated/determined by the multi-function switch on the steering column.

The HI beam function must be enabled by the body control module (BCM).

The headlamp power travels through the multi-function switch at the steering column and is grounded through CKT 750 (BLK).

The flash-to-pass function is also activated by the multi-function switch on the steering column. It is powered by CKT 1840 (ORN) and enabled through the body control module (BCM) via CKT 307 (YEL).

For a description of the RPO Code(s) shown in this article/images refer to the RPO Code List found at Vehicle/Application ID

Check Underhood Fuse Number 8 that is a 40 amp Labeled "Lighting"

Check IP Fuse number 15 Labeled "TBC" 10 amp.

Check IP fuse number 9 labeled PK LPS 20 amp. while you are there.

Check Headlamp under hood relay in underhood fuse block.

If you have not found the problem, the next check is the Headlamp Panel and Dimmer check to see that power in and power out are OK. Orange wire power in, and Brown wire power out to see that switch is functioning.

Next check is to access check for power at tan and white and yellow wires at headlamps.

Check underhood fuse block for HEADLAMP Fuses RH and LH getting power with a 12v. test lamp. They are powered by/hrough the headlamp relay.

See the wiring diagram below:----





These check must me done to do the diagnosis on this system.

Also access the steering column multi-function switch to check for power at the blue wire for power in and the tan wire for power out.


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Car no start:--