DIY: How-To-Enable DRL – 2007 Tundra

[phobos512]

Oops, noticed (I think) a typo in the document:

CAUTION!!!!!!!
Before you start make sure you do the following to isolate electrical
system components.
1. Disconnect the Negative Terminal from the Battery.
2. Find and Unplug Connectors J29 from the Main Body ECU
3. Find and Unplug Connector J3 from the Flasher Relay
4. Find and Unplug Connector A10 from behind the driver side headlight.
5. I strongly recommend that you solder all wire connections

Shouldn't Step 2 say J29 from the Flasher Relay, and Step 3 say J3 from the Main Body ECU?

[daless2]

Originally Posted by phobos512

Oops, noticed (I think) a typo in the document:

CAUTION!!!!!!!
Before you start make sure you do the following to isolate electrical
system components.
1. Disconnect the Negative Terminal from the Battery.
2. Find and Unplug Connectors J29 from the Main Body ECU
3. Find and Unplug Connector J3 from the Flasher Relay
4. Find and Unplug Connector A10 from behind the driver side headlight.
5. I strongly recommend that you solder all wire connections

Shouldn't Step 2 say J29 from the Flasher Relay, and Step 3 say J3 from the Main Body ECU?

Hi Matt,

You’re absolutely correct; I have that typo in the document. I am pursuing getting the original post updated with a new file that corrects this typo. In the mean time I will post the correct PDF below.

Also, I am posting a drawing that will explain how to remove the DRL / Flasher relay below.

Have a great evening,

Frank

[phobos512]

Thanks Frank for getting back to me and for the drawing. That helps even more than the pictures and explains why I wasn't able to find that bolt last night.

Last question I have for you, I forgot to ask it via those PMs...Is it OK to drive the truck with the flasher relay out until I get the DRL version?

[daless2]

Originally Posted by phobos512

Thanks Frank for getting back to me and for the drawing. That helps even more than the pictures and explains why I wasn't able to find that bolt last night.

Last question I have for you, I forgot to ask it via those PMs...Is it OK to drive the truck with the flasher relay out until I get the DRL version?

I Don't know for sure as I have never done this, but I would think the only problem will be that the turn signals will not work. I can't imagine any other problem from driving without the DRL/Flasher relay.

Wish i could be more definitive.

Frank

[zpaul]

Originally Posted by daless2

Hi Zpaul,

I have some information for you that might help. Some of this info is Fact, some I highly suspect to be fact but cannot directly prove.

I can tell you as fact that the Turn Signal/DRL Lights on your Tundra using the Auto Light Mode SHOULD turn OFF when the Auto Mode Turns on the headlights.

In other words, yours are not working as they should be with this design.

I tried to verify this via the electrical diagrams, but could not make that determination based on the diagrams alone. One never knows what goes on inside the computer black boxes. At least not all the way.



This morning I called a young man who lives nearby who I had help install this DRL modification. He has Auto Mode Lights. I asked him if I could stop by and run some tests on his truck to see how the DRL/Turn Signals lights work when the Auto Light Function was used.

Long story short, He told me to drive over to where he works, gave me the keys and let me test away.



His Tundra is a 2007 Limited Crew Cab, with Auto Light Function and came from the factory WITH OUT DRL. He and I installed this DRL Modification several months ago.

On his truck, with ignition key “ON”, and the headlights are OFF, the DRL/Turn Signals are “ON”. This is goodness.

When the Headlights are Turned ON, either by the switch, or by the Auto Function (I had to cover the sensor to make this happen) the DRL/Turn Signals Do Indeed Turn Off, as they should.

What this tells me is that this design does work, even in Auto Light Mode.



What I Believe


Something is probably wrong with your installation, most likely involving Relay “B”.


When Relay “B” is at REST (Not energized because the headlights are OFF) it provides a ground to the DRL Relay. This turns the DRL/Turn Signal bulbs “ON”.


When relay “B” is “Energized” (This happens when the headlights are ON) the Ground path to the DRL relay is broken, or “Opened”, effectively turning the DRL/Turn Signal lamps “Off”



To be more specific I would be looking for a problem in these areas.


1) Is Relay “B” Good? It is rare but I have seen new relays fail right out of the box. To test, swap relay “A” with relay “B”. See if the DRL still work. If not, the relay is bad.

2) Check the wire going from Pin 86 on Relay “B” to the left front headlight.

Make sure this tap is mechanically and electrically sound near the headlight. If it is not, Relay “B” will never energize when the headlights are on. When Relay “B” is energized, it shuts off the Ground Signal going to the DRL Relay, which turns the DRL/Turn Signals Off.

3) Make sure there is NO WIRE connecting pin 87 on relay "B" to anything at all. This Pin is not used and cannot be connected to anything, especially not to a ground.

4) If you are using a relay socket to plug your relay into make sure the female connectors in this socket are sound mechanically and electrically. It wouldn’t be the first time one of these failed.

5) Double check all your wiring and electrical connections.

I am convinced something is preventing relay “B” from working. Time invested in checking this out should be worth your while.

Hope this helps you out my friend. If it doesn’t, I’m more then willing to continue to help trouble shooting this with you.

Have a great day,

Frank

Frank, I finally found the time to go back and fix it. Your wiring instructions were modified for my install, that is why it was not working. The wiring was done without running it to the headlights plus one relay was eliminated, that caused all the problems. But thanks for your replies and help.
It finally works like it should.
For some reason I do not see much Tundras with DRL in Baltimore area.

[daless2]

Originally Posted by zpaul

Frank, I finally found the time to go back and fix it. Your wiring instructions were modified for my install, that is why it was not working. The wiring was done without running it to the headlights plus one relay was eliminated, that caused all the problems. But thanks for your replies and help.
It finally works like it should.
For some reason I do not see much Tundras with DRL in Baltimore area.

Thanks for the feedback, glad you got it working!

Have a great evening.

Frank

[needatundra]

Originally Posted by leonard6864

Just finished the install. Amazing instructions!!! Works perfect. Thanks a million.
The only problem is the dealer that brought the truck into Canada did a hack job installation under the hood with an aftermarket relay. They spliced wires and didn't solder. I removed what they did and put your installation in. They had the low beams coming on which was dimming the interior lights during daytime hours.

Thanks again!

Milton Toyota hacked mine up pretty good too.
Leonardo, how much was the relay from Barrie Toyota? I'm fearing they're gonna hose us Canadians for it.

[bucstundra]

Daless, great job on the instructions. Just a quick question. Would this mod also work on an 08? Thanks.

[daless2]

Originally Posted by bucstundra

Daless, great job on the instructions. Just a quick question. Would this mod also work on an 08? Thanks.

Yes, this mod will work on the 08 model year as well.

Have a great day,

Frank

[toyblue]

hi this mod interest me since i bought an american truck and brought it to Canada i would like to know if this mod dims the light on the instrument cluster in particular the info center the mod they did on my truck dims the lights it makes hard to read in the daytime Thanks

[daless2]

Originally Posted by toyblue

hi this mod interest me since i bought an american truck and brought it to Canada i would like to know if this mod dims the light on the instrument cluster in particular the info center the mod they did on my truck dims the lights it makes hard to read in the daytime Thanks

No, this mod Will NOT dim the Instrument Cluster Lights of the Info Center display, unless or intill you turn your parking lights or headlights on.

Frank

[the_greenhorn]

daless2, great post - very detailed. I have yet another question for you. I have an 08 CM with auto headlights and DRL's. I have been looking for a wiring diagram to add a simple switch to turn on/off my DRL's at will. Based on the diagram in your instructions, couldn't i put a switch in the same location that your diagram shows? Couldn't I just tap into J29 pin #3 white wire from ignition on and install the switch?

It sounds simple, but just wanted to run this by you since you obviously are very knowledgeable about the subject.

thanks in advance

[daless2]

Originally Posted by the_greenhorn

daless2, great post - very detailed. I have yet another question for you. I have an 08 CM with auto headlights and DRL's. I have been looking for a wiring diagram to add a simple switch to turn on/off my DRL's at will. Based on the diagram in your instructions, couldn't i put a switch in the same location that your diagram shows? Couldn't I just tap into J29 pin #3 white wire from ignition on and install the switch?

It sounds simple, but just wanted to run this by you since you obviously are very knowledgeable about the subject.

thanks in advance

Hi Greenhorn,

Thank you for your kind words.

If I understand it correctly you have an 08 with auto lights and Factory DRL and you want the ability to turn the DRL on and off at will using and on/off switch.

Is that correct?

I would not advise you to install the switch in the FACTORY wiring at J29, pin #3. This will work, but it will cause unintended consequences to the Turn Signals and the Hazard Warning Lights.


That said, I can give you some direction that will work.

Find connector J29. It is the one that plugs into the DRL/Flasher Relay.

Fine the Solid GRAY wire in pin position #5.

Insert your switch in this wire.


When the switch is turn on (Closed) your DRL will work as they do right now.

When your switch is off (Open) your DRL will be turned off.


This gray wire provides a ground signal to the DRL/Flasher Relay, from the Main Body ECU. By opening this wire with a switch the DRL/Flasher relay will no longer receive the ground signal to turn the DRL on.


I hope I was able to make this clear to you. If not let me know and I will give it another try.

Have a great day,

Frank

[the_greenhorn]

Thank you very much Frank, I'll try this and let you know. I just ordered a nice little rocker switch so when it comes in i'll hook it up and let everybody know. i may even be inclined to take some pictures for you to add to your document if you wish?

Thanks,
Rick

[daless2]

Originally Posted by the_greenhorn

Thank you very much Frank, I'll try this and let you know. I just ordered a nice little rocker switch so when it comes in i'll hook it up and let everybody know. i may even be inclined to take some pictures for you to add to your document if you wish?

Thanks,
Rick

Hi Rick,

That would be great. Snap a few pic's and post them. I'll pick them up and update the original document for those who would like to do the same with their DRL Factory lights.

Frank