DRL (incandescent) on with ignition? 2020 Tacoma SR5

Srry I didn't mean to put down your work but I just don't see a need to complicate this for something that should be trivial to do and require no modification to the truck.

 

Thank you so much for that but, unfortunately, if #20 on the combination switch is held to ground, the ECU will not activate the Tail circuit. That's why you suggested previously to ground through the #18 wires on the switch, which are tails. That would work because the switch physically grounds that wire. Since there are sensitive electronics up stream a diode seems necessary for protection. As long as 18 will still ground through a diode (I can easily check that tomorrow, and I really hope it does) that seems like the simplest method. Otherwise, it seems like it'll require something like caribe makaira posted.

As a reminder, the grounding through 18 diagram is below. If that's safe to do (for whatever electronics are upstream) and 18 will ground through the diode, this is actually quite simple. The wires are all easy to access, it's 1ft away from a suitable fuse to tap, etc. Thank you so much again.

I just don't trust my knowledge to know it is ok, but I can't think why it wouldn't be.

 

So your saying that if you turn the switch to Tail (Pin 18 grounded) but Pin 20 is still grounded the tail lights won't turn on?

 

That is correct. Sorry. But, the switch still physically grounds 18, so if I can ground through that safely it would work.

 

Dang I though I had it solved. Well I guess plan A still should work providing the diode in circuit works. Alot of relays use a resistor (although I don't know what value) across the terminals for voltage suppression, you can see one on the diagram across the Tail relay.

 

The generic 5pin I have had that internal resistor. I'm more uncertain if the diode will allow 18 to go to ground. I don't think they need current, only a voltage differential to operate. But that's something easily tested tomorrow.

 

Thank you very much for this! I think I would change the Fog tap to the Tail wire. My reasoning is that when the combination switch is on the tails position, grounding that will allow the DRL and all other lights to be fully controlled by the computer again, same as when turns or haz are selected on the stalk. Selecting any of those would return the DRL to factory operation controlled entierely by the truck along with allowing the proper operation of fogs and headlights with respect to DRL and to each other

If I'm understanding you correctly, turns/haz input can be had at C9 but the Tails input goes to a connector at the the MBECU. See my two images below, these are from a 2016 service manual, that is dated 2015, so if the 2020 are different I wouldn't see those differences in my copy. But, don't all of those input wires go to the combination SWITCH? If so, is there no reason I cannot tap in st the combination switch and connector C11?

Thank you again! Regardless of the outcome here I am learning so much and I apprecaite that.

 

Are fog lights required? If not, is the easy answer some plastic blanks and temp removal just for inspection?

 

One more time:
Canadian Regs require DRL to be OFF when fog lamps are ON. US Taco doesn't comply, so the fog relay actuation wire (beige) on F1 connector is tapped (posi-tap so wire is not severed).
Turning DRL feature OFF at Head Unit disables DRL feature on lights stalk switch. Makes turning OFF DRL by driver unavailable, which also complies with
Adding the harness supplies the DRL feature back
Diodes prevent feedback to HAZARD/TURN circuit.
Tapping the RIGHT/LEFT/HAZARDS (-) controls relay turning OFF the DRL feature (Same as the FOG wire tap) allowing lamp to flash.

The only missing control is DRL OFF when Headlights are selected. This would require another tap to relay from LOW beam select at C9 not C11.
C11 has parking and LOW beams parallel selected via light stalk.
If you tap only the PARKING wire on C11, you loose the DRL at parking which would go against

 

Thank you so much!

Just a bit more clarification, to help me better understand the truck wiring, please.
1. where do the turns and haz wires (input sensor wires, correct?) at C9 come from?
2. Same as 1 for Lows. Where is the other end of the Low wire at C9?
3. The diodes in your last drawing at each turn and hazard (at C9). Those isolate the three wires we use to ground our added relay. But, do those diodes also protect the combination meter from being backfed 12v? When none of them are grounded, wouldn't the combination meter input see 12v from the battery (higher current) while those same inputs (pinsl on the combination meter would have 12v from the meter itself,with virtually no current? Is that a danger to the combination meter here?
4. Do my attached diagrams below correctly describe the wiring of the combination stalk switch with regard to both Combination meter (C9 connector) and the MB-ECU (M6 connector)?

 

For HAZARDS/TURNS the pcb is inside the Combination meter. The light stalk provides activation via ground, as the drawing you've posted.
Small gauge wire, same size as the C11 ones are in parallel with circuits tapped.

 

They actually show the issue with you have for #20 on a Taco with high beam switch.

 

I guess I'm dense. Can you explain what this issue is and how the diagram shows it?

 

And one more time, the US Taco does comply with that. DRL turns off with Heads per regs. DRL turns off with Fogs, per regs. Fogs turn off with Highs, per regs..
......
post #50

The only way I can see that my US Taco (2020 SR5) does NOT comply with Canadian regs is that there is an OFF position on the stalk, which turns off all lights, including DRL.
Canadian regs say DRL must be on when the truck is on (technically in motion but ON is easier) UNLESS the headlights or fogs are on, then DRL must be OFF.
DRL CAN be on with highs (I think) but that is not a requirement and mine are not on with hghs becasue lows are always on with highs also, as stock from factory.

 

I saw the *2. But, how is that a problem for me? I understand that all thos ewires from the stalk go to M6 on the MBECU. I understand now that other wires fo rturns and hazards go to the Combination meter via C9.

I'm not trying to be a jerk here. I honestly don't understand what this is supposed to explain to me. Maybe I don't know how to read those diagrams right.

And again, I'm not struggling with the auto brights (which I don't even use and I'll pull the switch if it is an issue).

 

Maybe a letter to Toyota engineering would assist with a solution.

 

Would it be easier to get Canadian variant MB CU, switches, relays, etc and do a swap?

 

Just marking this so I can catch up at work tomorrow hopefully.... I haven't looked at the solutions yet, but this is doable fairly easy through the stalk, or even a fuse tap of you wanted to keep it all under the hood. I make a cheaper variant of the SR LED conversion harness that would do this with different plugs. But this may have been solved, I will try to catch up, so sorry if I am just rambling

 

Thank you for the reply! I did proceed with a solution using only the stalk switch wiring, it has been installed and seems to be working properly for 2 days now.

I'll give you a quick recap since you said y9u haven't read through the thread, and there's a lot of me writing a lot to learn and explain myself clearly, which I'm bad at.

I have a 2020 Tacoma SR5. Stock incandescent/halogen up front. Combined DRL and turns with the amber bulb and a single wire from the combination meter that provides 12v when the bright filament needs to be on for DRL or Turn.
I'll also mention that this truck allows Parking, Heads and Fogs to be turned on using the stalk switch even with ignition off and no key. I don't think that is necessary to keep but it is very handy.
The truck has AUTO highbeams (push button switch to left of left knee on dash) but does not have auto lights.
Stock Stalk switch has 4 positions, lowest being OFF, where no lights come on regardless of ignition. Then DRL with only DRL (or turns when called for) on with ignition, then a Parking/Tails position then a Headlight position.
I am moving to Canada where DRL must turn on with the ignition (or vehicle motion) and must not be able to be turned off while Ignition or moving. The DRL must also go off with lows or fogs.
Checking through the Canadian regs (as best I can), my truck controlls all lights correctly (DRL off with lows or fogs, fogs off with highs) EXCEPT that the stalk switch has a functioning OFF position. I THINK Canadian sold Tacomas from that era use a 3 position stalk switch that eliminates the OFF option, meanig the lowest stalk setting is DRL. Without that physical OFF position on the stalk, my vehicle would otherwise pass the required inspection for import.
Grounding the DRL wire on the stalk does turn on the DRL with ignition but holding it to ground prevents the ECU/Combination meter from correctly controlling other light systems, becasue the switch physically does not ground the DRL wire (#20, white on C11 connector/Stalk) in Park and Head positions. Thus, holding 20 to ground at all times confuses the "computers". 20 being grounded still alllows Turns and other safety light circuits to work properly. The mechanics of the stalk switch still function properly when 20 is held to ground, other wires such as the Tails/Heads (#18 green at C11) are grounded as an input signal to the Combination meter and/or MBECU. However, to repeat, if 20 is held to ground always, then parking/tails and heads do not work properly.

So, I needed to ground 20 when the stalk is OFF (or in DRL position, which it does from factory) and the ignition is on, but break ground when selecting park or headlights on the stalk. 18 green is grounded only in Park and Head positions on the stalk, providing a path to control.
Dm93 and Caribe Makaira both seem to suggest that I could ground though the stalk switch harness and that a diode should be used to protect the ECU and Combination meter from backfeeding.
I decided to go with adapting the stalk switch wiring as all the wiring I needed are together there and that is the easist spot to access.

One relay solves the problem of grounding 20 and turning on the DRL on with ignition and breaking ground with Park/Heads, but I loose the ability to turn on parkng or heads when the truck is off and/or no key. I believe this would solve the Canadian inspection requirements, but I do loose some functionality.
2 relays solves that problem too, allowing no ground to 20 when the truck is off (and/or no key) so that the parking and heads can be selected, but also turing on DRL with the ignition and again breaking ground when park/heads are selected.
Since turns/hazards (as well as brakes and reverse) all work correctly while 20 is grounded, this works "like factory" with the 3 position switch. I probbaly could have ordered a different stalk and swapped it in, but that would have cost a lot more and may have taken me longer than my time frame allows to import this vehicle during my move.


Below are some images of my solution with a quick description ABOVE each image. I'm not sure it is the best but it seems to work and was easy to impliment with parts I already had (or could get quickly).

Circuit diagram using 1 relay (any 12vdc relay seems like it would work). I did try a normal 5pin automotive relay, which worked, but was bulky. I am using much smaller relays, as seen in lower images. I've used these before with home automation DIY. The smaller versions also have much lower coil currents.
Using one relay allows the DRL to come on with the truck ignition and breaking ground to 20 when in park or head positions on the stalk. Head/Park/Fog lights will NOT turn on unless the truck is running



Circuit diagram with 2 relays. This allows the heads/park/fogs to work when selected on the switch even when the truck is not running. Again, I don't think that is necessary but it is a handy feature (drop you keys in the grass in from of the truck in the dark and you'll find it useful too) This allows full 'stock' fucntions as it came from the factory, while adding DRL on with ignition. The truck computers still turn the DRL off with lows and fogs, still blink the DRL for turns/hazards correctly, etc.



Here's the "module" I created, here being tested on my bench. The yellow test lead was replaced witha suitable wire after testing. The board was insulated and wrapped to prevent shorts also.
I did leave a relay connectted to a battery for quite a while, just to test for heat issues, and they barely warm to the touch. The coil only draw abouts 30mA, so they shouldn't get warm and the contacts only see like 1.5mV when grounding 20.


Close up of the pin side of the relays. See my drawing above.



Top side view of the module. You can get the exact relay info here also.. Again, these are incredibly common in household WIFI smart plugs and switches, thermostats and heat/humidty controllers, smart kitchen gadgets, etc. I'm betting most people have a couple of these somewhere in their house. These are the 12v coil style, they can be found with many different coil voltage options. Easily found at Amazon or your favorite electronics parts supplier (I like BC robotics if you are in Canada, but these are from Amazon for the faster shipping).


Here's where I mounted the module. The back has been well taped and insulted, wire connections reinforced and then firmly (but not aggressively) ziptied to this wiring harness. I'm using Fuse 3 of the MBECU fuse panel just to the left, by the driver's knee via an add a circuit (P.OUTLET1 Cigarette lighter). I didn't get a clear photo, but I split wire 18 at C11 and wired in a 1N4007 diode to protect from backfeeding the ECU. I then ran leads from 18 and 20 at C11 to this loaction, and used insulated spade connections for ease of removal should I ever want to.
Pulling the add a circuit completely disengages the module and returns the truck to complete factory operation, even without removing anything else.