DRL (incandescent) on with ignition? 2020 Tacoma SR5

Hi all!

Apologies for the longer post. I'm trying to give as much info as possible and also to coalate the info I've found from a variety of sources into one place, both fo rmysiefl and future folks with similar questions. My mian questions are in Bold, images at the end for reference.

A recent move from the US to Canada (BC) requires me to modify my truck to have DRL (daytime running light) that turn on with the ignition. I'd really appreciate some help trying to get the stock incandescent DRL working as required. Here, DRL are required whenever the vehicle is on and in motion, and must turn off when the headlights or fog lights are on. My Mexico made truck sold in the US does not do this. I have added a switched-on-at-ignition 5pin relay to the low beam circuit (H-LP LO relay) so that the low beams are always on when the truck is running or in the ON position (using an add-a-circuit at INJ fuse 44 in the main engine fuse box to ground the low beam relay, #59). Easy enough and I believe this will satisify the requirements (since they are the headlights,, they obviously don't need to turn off with the headlights). But, I like puzzles and trying to make things 'work right', so my real question:

Is possible to have the stock incandescent combo DRL/TURN bulbs function as always on DRL - but they need to turn off when the low beam headlight is on (truck has separate hi and low bulbs) AND MUST also maintain proper blinker/hazard function? Is that possible without using different bulbs (and housings, which I've no desire to buy) or without a complicated series of relays? I know the SR/5 models sold in Canada have this feature but I cannot figure out how it is achieved.

More info and backgroudn to what I've tried/learned so far....
I have a stock 2020 SR5 that has incandescent bulbs on the front that combine DRL and Turn on the same wire, which (I believe) connect directly to and are controlled by the combination meter (guage cluster). To do this the combination meter seems to send a 12v+ to the lights when the brighter DRL/Turn is needed. There is no separate DRL fuse in the main engine compartment fuse box (the space is empty and the terminals are missing from the box, though there is a hot side terminal at the DRL fuse, #41). The smaller accessory box connected to the side of the main box it is missing the DRL Relay and terminals. On the Driver Side Junction Block (DSJB) 1F, spot 30 is unpopulated (as expected).

But, I don't know if pin 30 coming from the DSJB is active but simply unwired, or if the DRL control from the ECU does not function at all on the SR/5, does anyone know? And if it does, does this cycle when the Turns are active or is that pin only for LED DRL, which do not function as Turns/Hazard? I think it is the second.

My turn signal/light stalk switch on the steering column (when viewed from the seat) has 4 positions, with fog controls being on an inner ring:

Headlights
Parking/marker FOG ON
DRL FOG OFF
OFF


I've spent a lot of time reading (especially this forum, and especially @carbibe makaira posts), looking at the wiring, searching a PDF of 2016 Tacoma Sevice Manual (very instructive and closest to mine I could find on the net), poking around with a multimeter, etc. I know enough circuitry and electronics to follow along but this is also my first Toyota and my first vehicle made after 2001, so this truck has a level of additional complication that I'm unfamiliar with. I am appreciating the chance to learn, especially which systems (and parts) are controlled by the various computers by GROUNDING circuits and which are contolled by SUPPLYING 12+. For example, having the low beams come on with the truck ignition was easy since the MB ECU grounds the controlling H-HP LO relay (rather than directly providing 12v) and because the lows never need to be off if the truck is running. The combined incandescent TURN/DRL, controlled entirely by the MB-ECU, seems to make it a lot harder.... or it does for me. Combining a fuctioning turn/hazard while normally off with low beams and fogs, is my challenge.

Digging into the stalk switch wiring (lights and turns) gives a bit more info. It seems that I could replace the stalk switch with one that does not have an OFF position (three position switch, TRD or OR models I think), thus the DRL would never turn off (though it would go off with the ignition). This can be partly emulated with my 4 position switch by grounding the stalk switch DRL wire (white, 20 at connector C11). However, if the DRL 20 wire remains grounded when switching the stalk to parking or headlights (or selecting Fogs on) then the grounded DRL wire prevents the computer (ecu or combo meter) from triggering the necessary relays, the DRL stays on always and the heads/fogs do not engage. Turn signals do still function correctly. The three position switch on higher models switch avoids this by elimainating an off position and grounding DRL wire 20 only when in the DRL (lowest) position but leaving it open when in park or headlight positions. I don't want to replace the stalk switch ($$$). I though about using the headlight wire on the stalk switch (19, yellow) as a trigger for a relay becasue even with DRL 20 grounded, the stalk switch still physically grounds Headlight when headlights are selected on the stalk switch. But, while there is 12v through the headlight wire 19, it has a very low current, too low to latch a normal automotive relay.

This is where my understanding of Toyota wiring as well as general electric theory runs out. It seems like using a different style of relay (one that will work with a coil current at or below ~70ma with 12v, the stalk switch seems to have about 70ma while generic Bosch style automotive relays seem to need 160ma or so to close) would allow for control by breaking the DRl 20 to ground connection when the park wire goes to ground. I'm sure such a thing must exist, but a quick search didnt turn one up.

One thing I'm especially not certain of is if I can ground a higher amperage 12v supply to those lower current grounds from the stalk switch and connector C11, or perhaps at the Driver Side Junction Box connector 1F. I believe I could ground safely at 1F but not at C11 (at least in general). But, the ECU is between C11 and F1, so going straight to 1F in this case would not help. It seems to me that if DRL stalk wire 20 is connected to ground through a relay (Normally closed), and that relay is triggered by the low current 12v Headlight wire (#19, yellow) on the stalk switch, then everyting should work as I want. I just cannot figure out how to use the low current stalk switch wiring to power a relay (or similar).

I'm uncertain if that is possible but I'm eager to learn! Or maybe theres an obvious method I'm missing that does not involve changing lights/fixtures or the stalk switch.

Thanks in advance!



Below is DRL/Turn circuit on my 2020 SR5.





Below is image of my engine comapartment fuse/relay box from factory.





Below is my mod to have low beams on when truck is on. Add a circuit from the INJ fuse, energizes the relay (5 pin, just off the image to the right). Energizing the added relay takes the LO beam relay leg to ground, turning on low beams whenever the truck is on or running.





Screenshot of low beam circuit from 2016+ Tacoma Sevice Manual (online PDF, link found in the big maintainance thread on this forum here.... https://www.tacomaworld.com/threads/3rd-gen-diy-maintenance-quick-reference.406712/)




Below shows location of 1F on DSJB and MB-ECU.



This is the 1F connector from the Driver Side Junction Block/MB-ECU from factory. Pin 30 (DRL, LED only I think)is unpopulated.




Below is the pinout for connector C11, the light stalk switch connector. This is testing each pin to ground based on switch position

 

Calling @caribe makaira , @Puppypunter ... I am a mere mortal and could never sift through the electrical information to sound smartly.

 

Thanks for that bump! Most of what I've 'figured out' about this was pieced together reading thier posts and replies on this forum.

 

The lamp in your Taco has 2 filaments, one HIGH (DRL/Hazards/Turn) and the other LOW (Parking). It would be complicated gadget to achieve what you like. Not impossible.
P.S. I have no info on how Canadian Taco do their all-around DRL feature.

 

They should already behave this way, 2nd gens are the same way.
When the switch is in the DRL position and the parking brake is released the front turn signals are the DRLs (always on) except when you have a turn signal on, when you turn the headlights and/or parking lights on the turn signal (bright) filaments turn off and the running light (dim) filaments turn on.

 

Thank you very much. Follow-up, are you familiar with any 12v relays that have a lower coil current requirement than the typical 4 and 5 pin automotive relays? Also, in the first drawing I posted above (which is a screen shot of a post you made a while back, so thanks) of the SR/5 combo DRL/turns would 85 be possible to tap in a live 12v+ supply between the meter and bulb? I know it won't help in my case, just as an exercise to understand how the system works. If both sources of 12v are the same, then adding them together should not matter. But, I don't know if a 12v supply coming from a computer is technically the same. In a case like this example, would a diode between a computer and the new tap in be appropriate?

Thanks again.

 

They do behave properly as the come from the factory. As you say, when on the DRL setting. However, the DRL can be turned off when the truck is running. That will not pass the inspection I have to go through to bring the truck into Canada. Here, DRL must be on as long as the vehicle is in motion (ignition on counts), they must come on automatically and they cannot be turned off if the vehicle is in motion.

I've wired my low beam headlights to work as DRL that are on whenever the truck is running or in the ON ignition position and, as far as I can tell reading the regulations,that will fulfill the inspection requirements.

If the truck had been sold here originally (built for sale in Canada) it would have been required to have the same. Ones sold here use the same incandescent lights but somehow have them setup as I describe. I'm fairly positive they simply use a different stalk light switch, that has no off position. Without an off position, DRL are on my default when the truck is on (I'm not sure if they also disable the headunit DRL settings). About half of the 3rd gen Tacomas I pass here, those that have incandescent lights, have the DRL working and about half don't. It is not a rule that's enforced much here, but to get it registered here the first time the inspection process is quite strict. Oddly, it's the only time the vehicle will be inspected in BC.... probably 30% of the vehicles I see on the road here daily would not pass the inspection.

I don't think I need to make the stock DRL work but I was curious if it was possible without buying a new stalk switch, and it seemed like a good problem to use to get a better understanding of how the truck really works.

 

Seems like BS that a vehicle is required to have DRL that can't be turned off there, here pretty much everything has DRL these days but most can be turned off.

I don't see a way to accomplish this using factory lights as the DRL segment of the switch is a ground input to the Body ECU which communicates to the Combination Meter via CAN.
When the switch is in the off position it simply opens the Auto/DRL pin, only difference between US and Canada models apparently is the switch.

I wonder if you could just scrub off the Off label on the stalk if anyone would notice.

 

On connector C11, wire #20 - the one that goes to the light stalk, you could jump it to ground and bypass the DRL switch. That way DRL is on after releasing the parking brake and can't be turned off.


@kmorgan3 might still have materials to assemble this for you. $$

 

But how would the Body ECU react when the tail/headlights are turned on? The Auto/DRL pin should turn off when tail/headlights are selected.

 

DRL circuit turns off upon selecting Low Beams.
Don't know if that would comply with Canadian Regs.

 

Yea it's supposed to but if you permanently ground the wire it wouldn't unless the Body ECU decides to turn them off when the headlights are selected on.

I guess you could accomplish it by using a relay triggered off the Tail terminal of the switch, ground the Auto/DRL wire on pin 87a (normally closed) then when the switch is turned to tail the relay activates and 87a turns off.

I think I'd just buy a switch rather than hack up all my wiring.

 

Well, if you look closer, the stalk doesn't turn them OFF going to other selection. The rotation/selection is one way up or down. If selection is OFF, all is OFF. One position "up" is DRL, next position is DRL and Parking, etc. etc.
The MBECU does the OFF when LOW beams are selected.
Test it. Be looking at the headlights, and have someone turn the stalk. Parking Brake released, 20 grounded. Then rotate all positions.
Report back.

 

All this is assuming OP's Taco DOES NOT have light sensor.

 

Seems to according to the diagram but hey I guess try it and see what happens.

 

Thank you both for your input and advice! I find it very helpful to see others walk through a problem and I appreciate that it seems I was on the right track.

This was honetly the first thing I tried. It seemed easy until I realized that none of the wires to/from C11 on the stalk switch have much current. They are 12v but only seem to have around 70mA when grounded. That is not enough current to activate the coil of a normal automotive relay, whcih tend to need around 150mA to hold the coil (or so I've read). The first thing I tried was a relay on the headlight wire, it cannot activate the coil. If I could find a relay that had a lower min coil current requirement and took 12v (or conceivably lower if I utilize the 5v USB or a buck/boost converter, or an LMxxxx voltage regulator) that would absolutely be the "easist" fix, aside from replacing the stalk switch, which would cost vastly more and take longer than I have to get to me. Grounding 20 does indeed turn on the DRL at ignition, but holding 20 to ground prevents the ECU (or something similar) from energizing the other light circuits as necessarty, including all rear lights. Selecting park or headlights on the stalk does not work when 20 is held to ground. See more below.

Also, sharpie hides the white lettering on the stalk very well (and wipes off easily with isopropyl alcohol), but the stalk has a physical off position, and that is the issue, OFF position means it can be turned off while in motion. I agree it is silly, especially since this vehicle will never be inspected for this again ( even if sold and re-registered by someone else) but this is not a fight I can win, so I'm making do :/ Low beams always on should satisfy them and let me register it here, then (and this is what one inspector told me) after you can do whatever you want becuase the vehicle will never be checked again. Want no lights and a 10" lift kit (min here is 4 +-), want to remove the cat, go ahead casue there will never be another required inspection. Given the vehicles i see on the road daily, I believe that. When I called to ask about the inspection process I asked about emmissions testing (since I've had to do that in two of the 4 states I've lived in) and the guy didn't even understand the question, and laughed when I explained it. When I went into town the other day (about a 20 mile round trip), I counted 17 cars that didn't have any lights on and I didnt try to count all the ones with some light burned out, or toher glaring safety issue. This wasn't major city driving, I wasn't on the highway. Saw a few hundred cars on that drive. That is pretty consistent with every drive I take here.

I though it was a progression to. I assumed it would work as: Nothing, DRL, DRL+ Park, then Park+Headlights (since DRL would go off when headlights are on anyway, and I think that is also a US requirement for autos sold there). Tried this, and went through it all very methodically. OFF is everyting OFF. DRL is DRL on only (though turns over-ride that since they share the same wire/filiment in the bulb and the cluster does all the control). Parking on should allow DRL with parking, and does as from factory, but selecting park on the stalk does NOT keep pin 20 grounded on the switch. When you select park it seems the ECU makes the decision to also turn on the DRL filiment in addition to powering both front and real parking/markers/license light, or pulsing when turn/hazard is called. Given the diagram you linked and similar that I've seen elsewhere, I though it was progressive, but it does not seem to be in testing, unless im testing it wrong, which is certainly possible. When you select headlights on the switch pin 20 is still not grounded, though it should not be becasue DRL should never be on with either headlight. It might not be very clear or well drawn, but my hand drawn diagram of C11 with numbers, colors and actions is in my original post. The description at each pin says what switch positions take that pin/wire to ground. On my truck (SR5 with factory incandescent or halogen bulbs everywhere), the only time pin/wire 20 (DRL) is grounded is when DRL is selected on the stalk. In the OFF, Park and headlight positions 20 is NOT grounded. Pin 19 (yellow) is only grounded when the headlight position is selected, 11 is only grounded when left turn is selected, etc Holding 20 to ground only works until you need tails, fogs or headlights, then holding 20 to ground prevents them rest from coming on.

But, and this does seme like a bonus, if you hold 20 to ground the turns still work properly, regardless of stalk position. Turns are the only thing that work properly if you hold 20 to ground, which makes sense since turns/drl are controlled directly by the cluster and becasue if only DRL is selected on the stalk under factory conditions, 20 is grounded and the turns still work.

I have a high/lo auto dim option but I do not believe there is an Auto to turn the headlighs or DRL on or off based on ambient light, only to dim highs. There is no Auto on the light stalk, there is no physical auto switch and there is nothing in the headunit or cluster that mentions auto lights. Maybe it is hiding somewhere. I have seen some images of stalks that have AUTO/DRL (and no OFF iirc) but mine is not labeled that way.

I do think that if I could find an appropriote relay (12v with low minimum coil current, though 5v would be possible), then I could use the headlight part of the stalk switch (since the physical stalk switch still grounds properly) as you describe, using the normally closed contact to ground 20 (DRL do not seem to work when the ignition is off, though park and heads will work with ignition off, and even without a key in) and grounding 19 headlights through the relay to turn off DRL when heads are on. Again, turns still work properly when 20 is held low, even if it is held low artifically and not via the switch or ECU/combination meter.

Would it be possible to use a different 12v source taken through a relay to ground using the combination switch wires as the ground, since the stalk wires do not have enough current on their own to power a standard automotive relay coil? Or is that a recipe for disaster with the cluster or ecu? I would think it depends on the source of both 12v signals. If both have the same 12v source it would be fine but if the cluster/ecu is isolated in any way that might cause an issue. I did notice that the ground at pin 8 on C11 only seems to ground the fog. Ground at pin 15 grounds the rest. Grounds 15 and 8 do not seem to be connected internally, but I may be misremembering that and I'll try to check that again. Since a normal relay coil draws at most 200mA (I've read 160mA is typical), I feel the stalk switch wiring, and probably the switch contacts themselves, are safe.

And now I've hit my usual roadblock of knowing enough to ask questions but not enough to answer them. I've tried looking into this topic just a little but haven't gotten anywhere. If it was safe to ground a bit more current through the stalk switch (say up to 200mA), then power can easily be had using an add a circuit to a switched fuse at the MB_ECU/Driver Side Junction Block, which is about 1 foot away. But again, I don't know if that is safe. I think one would have to control the pin 20 to ground relay using another stalk switch wire, because while the stalk works when 20 is grounded, the ecu/cluster does not seem to respond with any lights until 20 is ungrounded, so you cannot pull a signal for the relay from any lighting circuit after the cluster, ecu, etc. If I can ground a bit more current through the stalk wiring, then the same relay currently controlling my lowbeams for DRL would easily work here instead, adn give the appearance and fucntion of 'Canadian factory' Tacomas.

Thanks again to all for the input and discussion!

 

It seems like a relay like this would work with the stalk switch wiring. These have a coil current <50mA, and coil voltage of 12vdc. I've used similar 5vdc coil versions with Arduino and Esp microcontrollers and I'd think these would work here too.


Tnisesm/6pcs DC 12V Coil SPST PCB Relay 5 Pins Mini Power Relay CAT73-5P-12V-BK
https://a.co/d/fGhGMAf

 

Your thinking of it backwards.
The circuits from the Body ECU to the switch are switched inputs (Pull Down type), they aren't supposed to deliver any current.

It's not nearly as neat as the drawings @caribe makaira makes but this is how I would accomplish it if I had to.



For more info on switched inputs and how they work.
https://youtu.be/HNa4iCziOzQ?si=jsKrmVujotnXc5IX

 

OP, having an auto light and sensor in your Taco negates my prior advice.

 

Thank you for the diagram (which is better than my drawings and conveys the info perfectly), video link and explaination!.
I think I understand a bit better now, and the pull up/down concept is somewhat familar to me from dabbling with Arduino and ESP style microcontrollers.
Let me check my understanding though, please.

-- The ecu monitors its pins and uses their high/lo state as a digital "switch" for internal (to the ecu) logic. The ECU does not use that circuit to provide any power. The ECU uses that Hi/Lo (1, 0) state to know if a circuit is on or off (specifically if a switch is open or closed) and then uses that info to do computer stuff. At the stalk switch, moving to tails/parking position grounds pin 18 (green on C11) pulls that pin from the ECU to ground (low). This change of state from High to Lo 'instructs' the ECU to do a task, turn on the tail/parking light circuit. It's like when I press the letter "D" on my computer keyboard, closing that switch tells the computer to add a D character at the curser position vs pressing the D on an old manual typewriter, where the key press does the actual work putting the letter on the paper.

-- But, taking an ECU pin to ground can also be used to control a relay/etc if that device is also allowed to ground a usable (higher current) 12v source. This is what you suggest I do in your drawing: using a 12v ignition source through a relay and connected to pin 18 (green, tails) at the stalk switch. When the stalk is turned to parking or headlights, 18 (green) is taken to ground, and along with it the added relay coil is also taken to ground, energizing the relay coil and opening the normally closed (NC) portion (30-87a). Thus when the parking lights or headlights are selected on teh switch, 20 is no longer grounded and everyting works like factory. When in DRL positions on the stalk, the switch grounds 20, but even though we already have it grounded through the NC part of the relay, ground is ground and everything functions as normal. When the stalk is in OFF and 20 is not held to ground (factory), the NC side of the added relay grounds 20, signaling the ECU to turn on the DRL. Grounding 20 does not power the DRL. Grounding 20 is how we tell the ECU to turn on the DRL.

??-- Again, just to make sure I'm not misunderstanding or making an error, grounding a "higher" current, 12V source from ignition by taping into the wire (18 green) between MB-ECU and the stalk switch will not backfeed the ECU with 12v+? I'm not worried about the switch or wiring as the wire guage suggests they should handle 200mA without issue. Also, I know combining two of the same voltage sources would be fine (like running two wires from the battery) but I don't know if the 12v from the ECU is technically a different source (maybe it's somehow isolated with a floating ground or something)?

But, is there any danger having an Ignition source of 12V on the ground side of the ECU? I know your drawing shows that, I just want to double check that I'm not making a mistake, misunderstaning or providing you with wrong info in some way. This is the part I understand the least about and since I think would be tying logic level 12v to ignition level 12v next to the ECU, I figure I'll make extra sure I understand the system. If it is safe, is it safe because thats how electricty works and I don't understand it well enough or becuase there is some kind of internal protection (diode or fuse) in the ECU that would protect it? Out of curiousity, are there any other examples of this being used normally on a vehicle? I ask not to question you but to better learn and understand the system, and I learn best with real life examples.

--Again, just to further my understanding of all this, would the low beam circuit (image below) with 12v going "to" the comuputer (at F1, 28) be a pull up circuit? The MB-ECU uses digital information from other sources (like the state of the stalk switch wire for the headlights) to alllow the circuit ot ground through the DSJB or the ECU itself. It might be more complicated internally but when the ECU thinks it should turn on the lowbeams it grounds #1 on the LO relay through pin 28 at connector 1F (though that grounding is really happening furter into the DSJB or ECU. The ECU does not provide any power to do this, just provides the path to ground when needed. The ECU is just a "digital switch" to ground. But, is the lowbeam circuit at the DSJB/ECU a pull up type? No, right, because while 12 goes toward the ECU, it isn't sensing there and is simply acting as a digital relay to ground? Right?

Again, thank you for the info and discussion!




For reference, the below shows how the combination switch, meter and lights are connected. DRL work exactly the same way, wire 20 from meter to switch to ground and a single wire from the combination meter to the Turn/DRL filament of the bulb. This is just to help me visualize things.