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keywords: DRL DTRL DRLs DTRls Daytime Day Time Running Light Lights tech disable disabling circuit board circuitry diagram schematic wiring headlights head light lights ebrake e brake e-brake emergency handbrake hand brake
Introduction:
It's finally here! After promising this for probably 3 or 4 years now, I've finally posted everything I know on the DRL system in one place. This has everything you ever wanted to know about the DRL system, but the factory service manual wouldn't tell you. I personally reverse engineered the controller with a mulitmeter in order to come up with the circuit diagram for the controller. Also you'll find info on how to effectively disable the DRLs in a manner that allows you to remove all the DRL components from the vehicle. This article only applies to MK2 or MK3 vehicles. If you have a MK4/5, you risk damage or malfunction to your headlight function if you follow the procedures listed here. Also note that I've specifically worked only on Canadian market DRL implementations. US or foreign market DRL systems may be different.

Daytime Running Light function
The Daytime Running Lights (which for the rest of this article will be refered to as 'DRLs') serve to illuminate the low beam headlights at reduced brightness whenever the vehicle is in a state that is capable of motion.

DRL system components

DRL controller
The DRL controller consists of a circuit board that has a simple diode based logic system which triggers a transistor which governs the operation of a relay that switches the headlight ground between the DRL resistor and the manual headlight switch circuit.


This is housed in a small black plastic box manufactured by Omron. The same part is used in both MK2 and MK3 vehicles.



The DRL controller is located on top of the dashboard support brace, just to the left of the steering column.

DRL resistor
The DRL resistor is a rather substancial sized high wattage ceramic resistor, housed in a vented steel box that disipates a portion of the headlight power.


Like the DRL controller, this part is also made by Omron and is used on both MK2 and MK3 vehicles. Electrically, the resistor is in circuit between the headlights and the vehicle ground. The resistor is physically located inside the driver's side front quarter panel.


DRL disabling
The following method supercedes all prior methods of disabling DRLs. By following the wiring diagram below, the vehicle's wiring is functionally equal to a 1989 model that never had DRLs. When complete, the DRL controller can be removed, while still allowing full normal function of the headlights as well as the ebrake warning light. Normally, direct removal of the DRL controller without correcting the wiring, would disable both these circuits. In addition the DRL resistor can be removed from the fender well, as it no longer has a function.



DRL controller connector:


Back side of connector:


DRL controller connector with modified wiring:

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Hey, Lihtan. On your post "Headlight relay mod with pics" you said it was better to do with the DRL disable. I want to know what works and what dosen't work after you disable the DRL's. I live in Puerto Rico and I don't want to do the headlight mod, being that I will disable the DRL like you said, if it will disable the other outer light because the ticket might be expensive.

lithan, you are a truly, genuine electrical engineer! awsome work...i hope this sticky applies to mk4 as well...

lithan, the pictures are dead!!!! i was planning to do this next weekend, would you still have these pictures handy?

Greg

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when the clutch drops, the BS stops

"Life's a rally, cut corners"

Can't ya just pull the parking brake lever up one click? Thats how I do it on a 96 and 2000 metro.

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I like my Metro's 96 and 2000.
The most trouble free cars on the road.
Chevrolet goofed up the day they stopped selling them.

Because then your brake warning system can't tell you about brake system problems. It also isn't going to do much if you have a wiring problem with the DRL system that's preventing the headlights from operating.

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hi, like a crazy man bent on doing a cool, new mod I went and did this on my MK4 back in March without noticing the connectors and wires are different. So I burnt out a few fuses (H.L,R + H.L,L) and now I just have the connector sheared off and all the wires stripped to try them at different connections. Now that I'm getting around to testing the lights, it's now imperative that I figure out what I'm doing. So now that I have the service manual for my 2000 I can at least see which wires do what. Here's a nice scan of the 2000 DRL connector. Notice it has two fewer connections than the MK3/MK2.


So what happens is that with all the wires not connected, my park lamps, highbeams and normal running lamps work, but my driver's headlight is doing the candle trick where it's dim and useless like I had on the 95 firefly but with the other headlight this time. following the same logic as the DRL disable for MK3 i tried to connect 3-8 and 1-9 but nothing different happened. only when i connect 1 to 5 the instrument cluster lights up. and as well my interior dashboard lights work. help me !

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1995 Firefly 1.3 SOHC 8VALVE MANUAL
2000 Firefly 1.3 SOHC 16VALVE AUTO. Goals: full restoration, achieve stock MPG and HP or higher, finished look should be 'stealthy' and unassuming. Engine will need to be rebuilt later on to restore compression levels.

oh my goodness. after studying the diagrams and trying a multitude of methods of wiring, the only conclusion i have is that the instrument cluster indicators that light up with the key in ON don't work without the DRL and the normal light's don't light up the running light indicator, but yes highbeam. i need some help here, getting confused and frustrated.

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1995 Firefly 1.3 SOHC 8VALVE MANUAL
2000 Firefly 1.3 SOHC 16VALVE AUTO. Goals: full restoration, achieve stock MPG and HP or higher, finished look should be 'stealthy' and unassuming. Engine will need to be rebuilt later on to restore compression levels.

ok I tried this,
I have a 1995 Geo Metro 1.0 5spd.

I disconnected the resistor, I pulled out the DRL module located on the RIGHT side of the steering column, My wires are different colors than your, or at least some of them. I popped them out of the connector, and rigged them together.

No change, low beams still dim, and slow to transition. Next I somehow blew a fuse, I replaced it, now I have no high beams at all. 12VDC is good at the lights themselves, but the ground is apparently gone. I checked on the light 1 relay, and found it at first to respond to my voltage tester, light on when the switch is turnd on, and light off when it was turned off, then magically I lost everything, no tail lights, no low beams, no response form the switch everything dead. In fact the only thing that still works is the high beam & flash. all the lights are now out. All the fuses are good?

This car is a freakin christine I swear! any ideas? Also when I was turning on the lights I was hearing a clicking that was apparently coming from somewhere behind the middle of the back of the engine.

Of course noting now.
I may have to rewire the whole damn system now.

Any ideas?

OK found that the rotory knob switch was malfunctioning, so I replaced it. Everything was back to square one again.
However now, I took the opportunity to install my HID light conversion. All I can say is,... HOLY COW OMG, 1,... it works,.... 2 I can see the light beams in the day time against my garage. High and low work perfectly!

Problem Solved!

I can do a H4 xenon bulb to HID comparison shot if anyone would like to see it!

OK, a follow up on the DRL issue.

Yes I installed the wonderous HID kit. And it worked great, but the Geo had the last laugh on that,... The aberrant stray voltage leaks, and even voltage when the lights are turned completely off, led to the Hi low beam controller on the HID system to fry. So I drove for a month or two with just low beams.

I have done this mod posted above, with no, or temporary success.

Today I took out the HID kit to see if I could restore my ability to have hi beams. Half the day later, I am now with a dead battery and having to rewire the entire system from scratch.

Im using a new relay to make the low beams separate from the entire stock lighting system. I have clipped the wires, and am using the relay to connect the ground directly to the low beam terminals actuated by the gauge lights circuit. By the time I got the setup wired the battery was too dead to use. The over all system can power one light perfectly, but two, and its like there isnt enough voltage, to power both, and the system dims into a nice copper colored light.

I may have to add in and separate the high beam system as well. There are so many stray grounds, and voltage readings the entire system needs to be replaced. Ill go old school and use a foot switch, I will. But my goal is to keep everything running off the stalk on the column.

Ill keep you posted and put up a schematic once I have it fixed.
Any ideas on this would be great.
Meanwhile here are some schematic pictures:

What year is your Metro?

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hi!
I am the owner of Chevrolet Metro 2000. I got sick of this DRL and I decided to remove it.
Figure http://teamswift.net/gallery/image.php? ... e_id=15362 to connect pins 3 and 8. unit DRL should be disconnected completely. Thus we retain the function of displaying the parking brake and the problems with the brake fluid.
That's all!
In this scheme there is no ballast resistor, all done on the field-effect transistor.
Sorry for my English.
Greetings from Russia:)

Would I be correct in saying that I can remove the DRL resistor? I have a 95 Metro LSI 1 liter 5-speed. Sorry for the dumb question, I just got my 95 and have already started the eco-mods. BTW, if anybody is local to me (I'm in Mount Vernon, WA) I would appreciate some help with modding my Metro.

Adam
(503)206-9067

MK4s don't use a ballast resistor. Instead the headlights are dimmed using PWM.

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Hi, I'm working on a 95 Firefly with the same DRL. I did this mod and it worked exactly how it was supposed to (with no problems, no blown fuses). Thank you very much for the excellent details and pics!

** For people that still have headlight problems after the mod, this is how I fixed mine.

Unfortunately this mod did not make my low beam headlights work (which was my problem). They came on once in a while and high beam only worked when pulling the signal stick forward. Since I could eliminate the DRL as a problem, I looked at other possibilities.

The problem for me was a clip with about 6 wires or so that plugged into the fuse box (located under the steering wheel. 3 Phillips screws had to be taken out to get the panel off that was covering the fuse box, DRL, etc.)

I simply unplugged the wire clips from the fuse box one at a time until I found one that looked burnt and melted up. There was only one wire that was blackened and one corresponding pin at the fuse box side that was black.

I took a small strip course sand paper, folded it in half and carefully sanded the black off the male and female ends. **be very careful not to bend the pin or it could break off!

I then sprayed electric contact cleaner on the cleaned areas (may not be needed) and let it dry for a min.

I squeezed a little dielectric grease into the female end of the clip to help make a better connection and reduce heat in the future. (may not be needed)

I then took a small strip of thin (approx 1mm thick) metal and cut a strip about 1/4" long (you could use a verity of metal, foil and wire for this) that would fit in the female hole to make a tighter fit and better connection. Heat may have melted some of the plastic leaving a loose fit. I bent the very end (about 3mm down) at 90 degrees so the small piece of metal wouldn't go all the way in the hole when plugged back into the fuse box (The dielectric grease helped hold it in place).

** Make sure its not to snug or it could bend the pin.

I then carefully plugged it back in (it was very snug, but it went in OK). I tried the headlights and the low beams worked perfect and so did the high beams.

Summarized; it was a clip at the fuse box not making a proper connection causing arching (sparking), causing blackening and eventually no connection at all. Fix this by cleaning the black off and making sure its a snug fit when plugging it back in or it will happen again over time.

** If this doesn't make sense to you, you probably shouldn't try it. If anything needs to be clarified I would be happy to do my best. I hope this is more helpful then confusing.

I know this is a very old topic, but I did this a little bit differently.

Instead of cutting the wires I just made a couple jumpers and put them in the identified slots.

I just spent the last year trying to get my 95 back on the road which included about a 4 month search of a replacement wiring harness under the dash which the previous owner had a "guy" work on it for him that totally butchered the harness past a repairable condition.