Hey this is all experimentation for. All of us. So strange that the same part number would be different inside. I see there is no IC on your board. Strange. What year car is yours? What I would try next is replacing the other shunt, then test.
LED Conversion with Hyperflash and Brake Lamp Failure Solution
- Thread starter mcrider
- Start date
Good morning!
I have a 91. I am not sure the MY of the FR-3501 I bought on ebay came from.
Should I replace the other shunt with another resistor (wire them in series) or should I use just solder in one resistor to replace both shunts? (wire across it).
I can't thank you enough!
I have a 91. I am not sure the MY of the FR-3501 I bought on ebay came from.
Should I replace the other shunt with another resistor (wire them in series) or should I use just solder in one resistor to replace both shunts? (wire across it).
I can't thank you enough!
OK, I went and took apart the flasher I removed from my car and it is just like yours (i.e. no IC and two shunts). I actually saw a third shunt running parallel to one of the relays. So there has been a spec change from Honda. So anything from here is a shot in the dark without know the original Flasher's design setpoints. The shunts are definitely in series. Here are some options:
1) Remove a shunt and see if this flasher will operate, If not then you know these shunts are definitely in series with the lamps. Go to Radio Shack and pick up an resistor pot that you can adjust across a wide range and put it in place of the shunt. You can then play with the setting to see when and if the hyperflash stops. Measure the pot and you know what size you need (or just solder the pot in an leave it. Watch you wattage and heat.
2) By a new flasher from the dealer. New should come with the IC and function like the one in the write-up. Bit pricey, but could avoid some hassle. You will need to know the amperage of your LED bulbs otherwise you will be back in the guessing game on resistor size.
I'd try option 1 first as it is just time and a POT is cheap.
The one thing that puzzles me is the third Shunt. I examined my photo from the one I modified and it is not there. So wild guess on what it does.
Good Luck.
1) Remove a shunt and see if this flasher will operate, If not then you know these shunts are definitely in series with the lamps. Go to Radio Shack and pick up an resistor pot that you can adjust across a wide range and put it in place of the shunt. You can then play with the setting to see when and if the hyperflash stops. Measure the pot and you know what size you need (or just solder the pot in an leave it. Watch you wattage and heat.
2) By a new flasher from the dealer. New should come with the IC and function like the one in the write-up. Bit pricey, but could avoid some hassle. You will need to know the amperage of your LED bulbs otherwise you will be back in the guessing game on resistor size.
I'd try option 1 first as it is just time and a POT is cheap.
The one thing that puzzles me is the third Shunt. I examined my photo from the one I modified and it is not there. So wild guess on what it does.
Good Luck.
1 watt should be OK. Just check how hot it gets with the flashers going
ok.. I got it working.
I took your suggestion and replaced the other shunt with another 0.12Ω, 1W resistor and now I am getting regular flashes with both hazard and directional, with parking lights on or off.
Ran it for ~10 minutes with parking lights on and felt just a smidge warmer from cold.
Now I just have to figure out what I am doing wrong with the brake light bypass that's blowing fuses... :biggrin:
I took your suggestion and replaced the other shunt with another 0.12Ω, 1W resistor and now I am getting regular flashes with both hazard and directional, with parking lights on or off.
Ran it for ~10 minutes with parking lights on and felt just a smidge warmer from cold.
Now I just have to figure out what I am doing wrong with the brake light bypass that's blowing fuses... :biggrin:
Congrats! The instructions in the write up for bypassing the lamp failure warning is directly out of the 1997 Service Manual. Make sure you are following the wiring color coding. You may also want to check and make sure the black wire is truly ground. That is the only thing different I did from the shop manual.
All my tail lights are still LED and my license place lights. I did not need any additional converter box and any special wiring.
Teen, you should share your BOM. The LED's you used must have a built in Load Resistor which will make things easier for folks that wish to convert, especially the turn signal lamps.
Sorry for the newbie question - but converting the flasher unit as per the DYI is only if you are going to run the LED's without load resistors, correct?
If you were to run the LED's with the load resistors, you wouldn't have to deal with converting the flasher unit, but then you would have to consider the extra power draw of the resistors, and the heat they generate - correct #2 ?
Thanks in advance,
Neil
It depends on the current drawn by your particular bulbs with resistors. If it's sufficient, then you may not need to mod the flasher. I suspect you will have to, even with resistors, but it may require different shunt resistors. Pretty straightforward to calculate what value resistors you need.
Ok - I've taken the plunge & have ordered all the LED's - can you tell me how to do the calculation for the require size of the shunt resistor(s) in the flasher conversion please?
Thanks!
The datasheet is here: http://pdf.datasheetcatalog.com/datasheet/toshiba/3835.pdf
You can see the shunt resistor (which you will be replacing) as Rs on p.4.
In the table on p.3, you can see that the Detection Voltage depends on the overall voltage, but the way it works is that when the voltage is below that level, the flasher goes to hyperflash mode. As you can see in the table, the detection voltage is higher for higher operating voltages. If the car is running, Vcc = 14.4 ~= 15V. From the table, the minimum detection voltage is 87 mV. At 12V operating voltage, the minimum detection voltage is 75 mV.
So you want to pick a resistor that will give no less than ~75 mV drop across the resistor when both bulbs on a side are good, and less than that when only one bulb is good.
Now we need to know info about your LED. I believe mine used 350 mA each. When you turn, you will be using one in front and one in back. So that's 700 mA for my LEDs. A 0.15 Ohm resistor creates a voltage drop of V = I*R = 0.700 * 0.15 = 0.105 V = 105 mV. That means the module will think that the lights are okay.
If one bulb fails, the current drops to 350 mA, giving a voltage drop of 0.350 * 0.15 = 52.5 mV, which is less than the detection voltage and hyperflashing would be triggered.
One thing to be careful about is the power dissipation. P = I^2 * R. So here, using the LEDs, P = 0.700 * 0.700 * 0.15 = 0.07 Watts. With Hazard lights on, you use all four bulbs, so the power goes up to 1.4^2 * .15 ~= 0.3 W. That means you need a 1/2 Watt resistor. Although, as mcrider pointed out in his very helpful writeup, you should have more of a margin for safety. He chose a 1W resistor. I actually used a 3.75W resistor, because it wasn't much more expensive and it seemed good. I used this one.
If you use incandescent bulbs with this modified flasher, you will have a current of about 9 Amps, so power dissipation of about 12 Watts. Poof goes the resistor and maybe starts a fire and the car burns to the ground. So please be sure to only use LEDs with your modified flasher module, and only the LEDs you used to calculate the appropriate resistor. (At least check the calculation if you change to different bulbs.)
Let me know if something didn't make sense. I chose the resistor that I went with, which was pretty easy to determine with a spreadsheet so I could try different values.
You can see the shunt resistor (which you will be replacing) as Rs on p.4.
In the table on p.3, you can see that the Detection Voltage depends on the overall voltage, but the way it works is that when the voltage is below that level, the flasher goes to hyperflash mode. As you can see in the table, the detection voltage is higher for higher operating voltages. If the car is running, Vcc = 14.4 ~= 15V. From the table, the minimum detection voltage is 87 mV. At 12V operating voltage, the minimum detection voltage is 75 mV.
So you want to pick a resistor that will give no less than ~75 mV drop across the resistor when both bulbs on a side are good, and less than that when only one bulb is good.
Now we need to know info about your LED. I believe mine used 350 mA each. When you turn, you will be using one in front and one in back. So that's 700 mA for my LEDs. A 0.15 Ohm resistor creates a voltage drop of V = I*R = 0.700 * 0.15 = 0.105 V = 105 mV. That means the module will think that the lights are okay.
If one bulb fails, the current drops to 350 mA, giving a voltage drop of 0.350 * 0.15 = 52.5 mV, which is less than the detection voltage and hyperflashing would be triggered.
One thing to be careful about is the power dissipation. P = I^2 * R. So here, using the LEDs, P = 0.700 * 0.700 * 0.15 = 0.07 Watts. With Hazard lights on, you use all four bulbs, so the power goes up to 1.4^2 * .15 ~= 0.3 W. That means you need a 1/2 Watt resistor. Although, as mcrider pointed out in his very helpful writeup, you should have more of a margin for safety. He chose a 1W resistor. I actually used a 3.75W resistor, because it wasn't much more expensive and it seemed good. I used this one.
If you use incandescent bulbs with this modified flasher, you will have a current of about 9 Amps, so power dissipation of about 12 Watts. Poof goes the resistor and maybe starts a fire and the car burns to the ground. So please be sure to only use LEDs with your modified flasher module, and only the LEDs you used to calculate the appropriate resistor. (At least check the calculation if you change to different bulbs.)
Let me know if something didn't make sense. I chose the resistor that I went with, which was pretty easy to determine with a spreadsheet so I could try different values.
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Ok. Just installed LED bulbs for my tail lights, did the ground on the passenger side and it cleared the brake lamp warning. But when I turn on my lights the brake lights are on as if I was pressing on the brakes, checked the ground and it seems fine, when I unplug the driver side tai lights the passenger side works fine. What am I missing here?
That is strange. One other Primer was have strange things happen like that. He ditched his LEDs and bought the ones I have listed in the write up and all worked fine.
Yes, that would be me. I originally purchased the Pilot brand sold at Autozone but the dual-element replacement version had issues that caused wackiness to ensue so I replaced those with the SuperbrightLEDs in mcrider's write up and all is well
Awww. Those are the one I bought. Spend 90 buck on them too.
- - - Updated - - -
I found the fix. Started by testing each build on the driverside since I knew the problem was on that side. Turned on the lights and they all turned on as if I was pressing the brakes. Removed each bulb and found one that when I removed it everything worked fine, for some reason it had a small metal ring at the bottom which touch both terminals. Removed it, reinstalled and everything works normal.
- - - Updated - - -
I found the fix. Started by testing each build on the driverside since I knew the problem was on that side. Turned on the lights and they all turned on as if I was pressing the brakes. Removed each bulb and found one that when I removed it everything worked fine, for some reason it had a small metal ring at the bottom which touch both terminals. Removed it, reinstalled and everything works normal.
Could someone explain to me (in common English the difference between a "normal" LED & A CANBUS LED please? I just went through & installed the brake light LED's (with McRider's jumper fix), and had the same problem as this Primer - my radio would dim every time I put on the brakes :-(
Lastly, if it must be CANBUS - are there any cheaper / but still good alternatives to superbrightleds?, as their prices are huge compared to most...
Thanks!
[MENTION=3875]Teej[/MENTION] care to share what exact bulbs you're using? Providing a link would help also.
Nothing overly special... bought at I think superbright LEDs.. But...
I do have a blue wire running tapped from the white/green wire to a grounding point. Maybe that's all you need.
You should check your ground point. I recall I tested that location and it was not a good ground. If the multipin connector in the photo is the same as in my write up, the black wire is a good ground.
Yeah I shaved off some of the coating and have had zero issues. Been like that now for almost 2 years (shrug)
I just fixed the LED hyperflashing problem with a simple mod to the Mitsuba FR-3501 flasher relay.
Instead of messing with the shunt resistors (marked RS on the board) I disabled the lamp-out sensing altogether. It's easier to just take a part out than to fiddle with getting the right resistor values.
Just remove the transistor marked T1 as shown above.
With a fine soldering iron and some solder wick, remove solder from the three leads of the transistor on the bottom of the circuit board. With needle nose pliers, grab the lead sticking out of the board and wiggle it to break loose the last of the solder. The transistor practically fell out of the board for me.
Put it back in the car and your flashers should operate at normal speed no matter what combination of LEDs and incandecent bulbs you use.
Truth in advertizing, I did this to my '93 Honda del Sol, not my NSX...oh wait, I don't have an NSX...but I wish I did. At least I have the same overpriced flasher relay!
Instead of messing with the shunt resistors (marked RS on the board) I disabled the lamp-out sensing altogether. It's easier to just take a part out than to fiddle with getting the right resistor values.
Just remove the transistor marked T1 as shown above.
With a fine soldering iron and some solder wick, remove solder from the three leads of the transistor on the bottom of the circuit board. With needle nose pliers, grab the lead sticking out of the board and wiggle it to break loose the last of the solder. The transistor practically fell out of the board for me.
Put it back in the car and your flashers should operate at normal speed no matter what combination of LEDs and incandecent bulbs you use.
Truth in advertizing, I did this to my '93 Honda del Sol, not my NSX...oh wait, I don't have an NSX...but I wish I did. At least I have the same overpriced flasher relay!
