LeX2K

After thinking about it's better to use the connector to relay base instead of how I did the above. Chance of failure is a bit high when pushing/pulling the relay in and out. 3D printing is a cool idea but probably not worth it unless there is reasonable demand for replacements.

LeX2K

More progress, made an interface/patch cable.

Relay base wire colours


Soldered up


Drilled a hole in the top of the relay case and used a rubber grommet


Completed harness


With flasher


Depending on the 5-pin relay you get the internals will of course be different, the Ford was was easy to gut others may require more hacking.

KahnBB6

iTrader: (5)

That is a super, super clean patch harness!!! I really love that attention to detail and finish! We think alike in this regard, haha

I think that Ford 5-pin relay is the best choice for now. Looks very good!

I can't wait to try it out!

I agree. This is why the patch harness is probably the best idea... unless we get a really sorted out two-piece 3D printed casing designed which people would have to print out, populate with all the components, etc. I like that idea still but this harness solution looks very solid as is.

Actually this has been demonstrated and done many times already with the original 92-94 SC flasher relay. It involves Dremel shaving the loop resistor wire/metal piece in a specific way. I wish there were something off the shelf that could be soldered right in after de-soldering the original loop but the shaving method is what most people tend to use.

Before you send out that original flasher relay is it even possible to determine the exact resistance properties of the original loop versus a thinner one suitable for LED use?

Based on our last PM conversation I think I will be making a switch to LED flasher bulbs. And I will pull out one of my spare tail lights to get you the exact number of rear 27 watt bulbs that populate each tail assembly.

Here's a thread detailing the LED conversion to the original 1992-1994 SC300/400 (and presumably Soarer Z30 1991-1994) flasher relay:

https://www.clublexus.com/forums/sc-...led-tails.html

And here's a DIY method (originally posted on the SoarerCentral forum I believe) pioneered for the 1991-1994 Soarer Z30's nearly identical signal flasher relay to convert to LED. Here there are piggyback capacitors being used rather than shaving the loop metal resistor:




I am tempted to try the piggyback capacitor method on one of my SC 92-94 flasher relays. Do you think these exact capacitor types used for the Soarer variant of this relay will also work just the same for the USA/Canada version relay?

Further, would a similar calculation for the correct rated capacitors to piggyback with also work for your Gen5 Camry flasher relay solution?

KahnBB6

iTrader: (5)

Also, just for reference to anyone reading who has an early Z30 Soarer, here are pictures of what the 1991-1994 Toyota Soarer Z30 signal flasher relay looks like. As you can see it's identical physically other than having a different color casing with a slightly different Toyota part number (P/N 81980-24010 for the 1991-1994 Z30 Toyota Soarer). I am unsure of its exact ratings or any differences in the circuitry compared to the U.S./Canada 92-94 SC flasher relay but I suspect it's the same or not substantially different. The Z30 Soarers have a digital instrument cluster vs the analog SC instrument cluster and perhaps that is why there are two different relays (I'm not sure honestly).

Just as with the U.S./Canada early flasher relay I feel these can also be rebuilt and made functional again with new OEM-spec/brand capacitors from Digi-Key or Mouser if they have issues... since they are also discontinued (so please folks, don't throw away a failing early style flasher relay! Get it capacitor serviced and try it out again!). Lexus2000, I think you stated that after the easy to replace capacitors the last thing to potentially fail in both flasher relay designs are the much smaller diodes on the reverse side? But I think those are less likely to fail than the electrolytic capacitors in the majority of cases?

But... if that fix to an original flasher relay does not work out for someone then I think Lexus2000 has nailed a solid alternative with the re-purposed Gen5 Toyota Camry flasher relay and DIY adapter harness!! It is more than likely that this alternative solution should work for both early SC300/400's and early Soarer Z30's.

Pictures of the 1991-1994 Z30 Soarer signal flasher relay. It's nearly identical to the 1992-1994 SC300/400 flasher relay:

LeX2K

Mostly that fancy stuff is for reliability but yes it makes the cable look clean.
Should be very easy to find as well.
Think I'll hold off sending it until I mod another Toyota flasher to work with LEDs.
I like the harness idea because then you can easily replace the flasher unit.
Reducing the shunt wire gauge via grinding will work but it's trial and error, better to find the resistance needed. Which is what I did. Was looking through some scrap boards to find a resistor then it dawned on me, I can use the wire out of a blower motor resistor. I straightened the coil out and soldered on to various places until I found a spot where the flasher works the best with LEDs.



Can't measure the resistance because my test meter is not accurate enough so measured the voltage drop and using Ohm's law I got 0.94 ohm so let's say 0.1 ohm. This makes the flasher work with a load of about 0.4 amps to 2.2 amps after that it no longer flashed the relay has built in current protection by the looks. I ran 4 LED bulbs, flasher worked then ran 6 it also worked. Current was 1.6 amps with 6 LED bulbs. One standard bulb (27 watt) causes the flasher to click once then stop, as I said probably current protection the higher resistance hence higher voltage across the resistor makes the unit think there is too much current.
Think what I'll do is buy a few resistors and make it so they can be swapped externally, meaning you can change them out to find out the best resistance for the LEDs you have. These seem to be the best form factor.
https://www.ebay.ca/itm/193531717091

Will see what the price comes to from Mouser or DigiKey but shipping usually makes it not worth it for a small order.

Another option is to use kanthal wire.

Says 2.04ohms per foot so a short piece of wire should work.

I wouldn't mod the original flasher unless you have a spare too much risk of damaging it. ....... oh on changing the capacitor on the Camry flasher, I was going to try that but it looks to be a bipolar cap I don't have any except ones that are really low values, the one in there 3.3 µF.

LeX2K

K I found a bipolar cap 2.2µF put it in series with the existing one didn't change how the Toyota flasher worked.

LeX2K

Another update. A 0.1Ω resistor works in the Toyota flasher to make it LED compatible, gives a working range of about 7 watts to 25 watts. That translates into 1-5 or 1-6 LED bulbs total. Total means hazards on, all bulbs flashing. Generally an LED turn signal bulb is 5-7 watts but some are much more for the crazy light output versions. If you need higher current then you can use a section of nichrome wire, or if you go high enough on the LED power the original Toyota flasher will simply work.


How many turn signal bulbs does the SC have exactly? I need this info before I can proceed.

KahnBB6

iTrader: (5)

This is excellent news! I really want it to work, however the total number of bulbs may present an issue but I hope not ultimately (see below).

Each stock tail light has three yellow 27W turn signal bulbs and each front headlight has one bulb. So that's four signal bulbs per side making eight turn signal bulbs (LH and RH) in total. If the little driver instrument cluster signal arrow lights also count then that would be one more additional bulb per each side but I don't think that counts?

From my 1993 SC300 owner's manual the bulbs wattages are:

Front Turn Signal Lights (x1 per each side): Type 1157 NA -- "27/8" Watts each (I think this can be taken as just 27 Watts per bulb at the front?)

Rear Turn Signal Lights (x3 per each side): Type 1156 -- 27 Watts each

With the hazard flasher button on and flashing both sides together all 1992-2000 SC300/400's will draw approximately 216 Watts(!) per flash. Maybe this is why from the perspective of late 1980's Toyota engineers the twin internal relay flasher setup was chosen. Although it's interesting that a different and more conventional flasher relay scheme was chosen for 1995-2000 SC's and Soarers.

With each LED bulb only drawing a maximum of 7W each the total draw would now be 56W with the hazard button on. If each LED signal bulb will only draw 5W each then the maximum draw would only be 40W with the hazard switch on.

However if this LED flasher relay solution can only support 6 bulbs in total then we're still short two bulbs. If the maximum wattage that can be supported is only 25W then we're still nowhere close unless there were 3W LED signal flasher bulbs in 1157 NA and 1156 types that can output the equivalent light of what the conventional 27W bulbs do.

The tail lights are very wide and wrap around the rear sides a little and the three bulbs per side for signal flashing do take advantage of that expanse.

The only way to reduce the number of rear turn signal flasher bulbs would be to gut the rear tail lights and go with a full LED retrofit such as the one Organized Garage Status has mentioned to me a while back. I don't know how they have intended to approach that electrically or if it's already a project that has been undertaken but for the purposes of this project I'm envisioning most SC owners sticking with conventional 1157 NA and 1156 bulb types that will twist into the standard factory original bulb receptacles and connectors.

When swapping 1997-2000 SC tail lights onto earlier model year SC's there is the infamous "hyperbilnk fix" that is required... while still using conventional 27W turn signal bulbs.

I suspect this is actually somewhat related to this current investigation but the problem seems to be amplified much more when trying to account for LED bulbs.

LeX2K

Damn, that's crazy. If I had an SC I'd convert to LED ASAP 216 watts is ridiculous and really it's more since the incandescent is very low resistance before it fully warms up.

So there are two issues
one) if the relays in the Toyota flasher are strong enough
two) if the 0.1Ω resistor will allow the flasher to work without over current protection kicking in.

BTW the LED flashers (like the one I bought) are listed at 150 watts max.

I'm going to have to test with 8 bulbs never thought I'd have to use that many lol.

LeX2K

Curiosity got the better of me so I tied in two more sockets now I have a total of 8. Toyota (not modded) flasher worked with up to six 27 watt bulbs after that over current protection activated. To make it work with 8 bulbs I did this:



Ran it in hazard mode for about 15 minutes the relay and especially the shunt resistors got quite warm not super hot though. For reference I did the same with the Lexus relay the shunt resistor on it got quite warm the rest of the unit not as warm.

Since I now have 8 sockets I populated them all with LED bulbs, some are high power others not. One one bank I measured 18 watts the other 16 so that's 34 watts total. The LED modded flasher works with this configuration. Bottom line is the Toyota flasher can be modded to work with the SC's stock bulb setup but long term reliability is unknown. For running LEDs this is easier, swapping the shunt for a 0.1Ω resistor should work with most setups. If not then you'll need a 0.08Ω resistor or something like that. In case it is not obvious, the lower the resistance of the shut resistor the higher the current possible through the flasher before protection kicks in.

On another note I did remove the shunt on the Lexus flasher and put in a 0.1Ω, it works with LEDs no problem. I put the original back in won't be messing with the Lexus unit anymore. Naturally it would be a whole lot easier to do testing if I owned an SC nothing beats real world testing vs. on the bench.

Another way to go about this is use two of these

It claims 162 watts so two of them would be fine. But at this point I don't want to spend any more money, haven't spent a lot but enough. If someone wants to donate me two of the above flashers I'll hack them to try and make them work with the SC.

KahnBB6

iTrader: (5)

Whoa... okay first I am going to highly consider modding a spare original 92-94 SC flasher relay for LED use soon. I will need to get the exact shunt resistor that you used to make it work.

Second, I'm happy to purchase and send over two of those Novita EP27 flashers to you. I'm wondering if I can just do it from the Canadian Amazon store to make it easier.

However it sounds like the Toyota Camry Gen5 flasher can be made to work.... reliably(?)... as long as the correct shunt resistor is soldered in and so long as it will strictly be for LED bulb use only. Maybe anyone using that solution should add a couple of homemade warning labels with a little Brother label printer or something like that in case the mistake of installing stock 27W bulbs were ever to be attempted.

LeX2K

This is what I used.

If you want I'll modify your SC flasher, of course at some point I will mail it back to you.
I'm sure we can work something out. But before going there, I'm going to try and disable the over current protection on the flasher meaning it will work with any load. This would make it perfect for LED bulb use and for safety I can add a fuse external to the flasher. I don't know if it is possible to disable the over current though.
There is no safety risk since the relay disables itself if current gets too high. But that also makes it a pain as it limits the scenarios it can be used in.

BTW for the SC rear lamp modules a person shouldn't be using an high brightness LED bulb since there are 3 of them. For example:

I am using these in two of my cars they are great, nice and bright and are true amber not yellow. But they are claimed 600 lumens which to my eyes is accurate that means in the SC your turn signals will be 1800 lumens that is downright blinding! It might be a challenge to find LED bulbs that have a good beam pattern, are true amber and are not super bright.

LeX2K

Good news can forget about shunt resistors, trying to hack two flashers together and all that I figured out how to disable the load sensing. The solution is quite simple:



Pin 10 of the Denso ASIC compares voltage between 12 volt input and the output side of the shunt resistor, we are talking millivolts. So to defeat the load sense I simply cut the trace going to pin 10, and fed it power through a 250KΩ resistor. Now the flasher doesn't care if you have no bulbs or 10 it works the same. There is no more shunt resistor I replaced it with a sold strand of copper wire.



The great thing is I can adapt this flasher for all my cars instead of the questionable Novita LED flashers I'm using. They are okay but the flash rate is too fast for one and I'm not sure of longevity. For SC applications this will work straight away* with the stock bulbs but I can't say if the relays can handle that much current, there is no current rating on the relays. Searching for Denso pm-2660303 or Denso 2660303 yielded nothing.

* can't say this with 100% certainty still needs to be tested on the car.

LeX2K

Ended up being much harder to modify this unit to be 3-pin compatible, wire spaghetti.


Here's a schematic for a typical 3-wire flasher, it's kinda goofy how it works.
https://i.imgur.com/H7BLc9J.png
Dunno if I'll actually put this hack job in my car, maybe I'll rewire the car to take the unmodified gen5 Camry unit.

NMDEFT

Firstly this is a great thread! The effort you guys have put in to help other Lexus owners is astonishing and much appreciated.

So for a total newb (me), is there a way for me to make my 93 SC400 5pin flasher (that has just stopped working) working again with the Gen 5 Camry flasher? And while I'm at it could I make it compatible with LED's?

This may sound like a super dumb question but you guys have some serious skills and I own a soldering iron. But that doesn't mean I could do any of the above.