SS #670 Mods: Disable DRLs

SS #670 Modifications:
Disable daytime running lights

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 heck of 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 console	Trim 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. Use a screw driver or similar tool to release the fog lamp and ASR connectors so that you can move the console trim out of the way.


Radio removed	DRL module

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


DRL connectors	Jumper 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. C1 is larger than C2.


DRL connector C1	DRL 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.

Adding a DRL and automatic headlights disable switch

Automatic headlights are actually handy and the real problem is with the way they're implemented 4th generation F-Body; it's not possible to turn the headlights off without turning the engine off.

Adding a switch is pretty easy. There are several female pins that are compatible with the C2 connector available from mouser.com including Delphi 12160812. Once you add a wire to the B position it's just a matter grounding it when you want to disable the DRL module.

If one wanted to be extra clever one could build a circuit ground the disable line on the DRL module when the headlamp switch was in the parking light position. Certainly this is the more recent vehicles with automatic headlights work. This would be a little bit tricky because you'd have to detect when the parking light circuit (9) is on but the headlight circuit (10) is off and then ground the DRL disable pin.

Can I just remove the DRL connector?

Yes, removing the C2 connector will disable DRL and automatic headlights. Unfortunately 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 4th gen Pontiac F-Body (which does not have automatic headlights) is wired.


Chevrolet ambient light sensor wiring	Pontiac 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

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

What about just leaving the ebrake on the last notch?

While it's true that leaving your emergency brake on the last notch will disable DRL and automatic headlights, you will also have to live with the eternal "BRAKE" light on your instrument cluster. If you have a manual transmission, it also makes it possible for you to accidentally pop the hatch while driving.

I've heard some state that leaving your emergency brake on the last notch disables ABS. This is false.

Buggering the ebrake switch is the same as leaving the emergency brake on the last notch.

Disconnecting C2 from the DRL module makes it impossible to pop the hatch in some circumstances (with the manual transmission anyway). It also disables the "BRAKE" light on your instrument cluster which comes in handy should you forget to completely disengage the emergency brake (or if you're low on brake fluid!)

How does all this apply to the Pontiac F-Body?

The Canadian Pontiac is basically the same as the Chevrolet. However the domestic Pontiac does not have automatic headlights. The factory shop manual schematic shows this is done by wiring the ambient light sensor inputs together. (For this reason it's ok to short out the ambient light sensor inputs on the Chevrolet if you just want to disable automatic headlights.)

Other sources of anti-DRL information

Association of Drivers Against Daytime Running Lights