This may be in in another post , I looked and I can't find one if there is one.

I decided to upgrade my lighting on 75 Cutlass. Everything but the front lights.
Everything works properly but the flashers.
Of course the blinker flashing becomes an issue once replaced.
I got a 2 flasher units from NAPA said they will work with led bulbs. Nope no go.
I got a Grote LED relay flasher 44891. 1amp to 20amp . It does NOT work either with LEDs in or one incandescent bulb in the circuit. So I pulled it out and put the original flasher back in again with all LED, no go. I then took the front signal led out and replaced it with an incandescent bulb, This circuit will flash properly with the original flasher relay.

Question is.... is it possible the LED flasher relays are not picking up the led bulbs because of the resistance if less than 1amp . Keep in mind, I replaced the back bulbs , marker lights and both front blinker bulbs.
.... Is it possible the flasher relays are polarity sensitive? I didn't want to switch wires and blow something. You would think a 2 wire flasher relay would be wired for our cars. They only plug in way.

 

I found this website that makes adapters to reverse polarity. I will just use wire to reverse if I need too.
From the website, does this make sense?... I didn't know this.

Turn Signal LED Flasher Relay with Polarity Adapter - 2 Prong 12V

• Two terminal flasher for LED conversion
• Includes clip-on adapter for reversing polarity - many older vehicles are wired backwards (incandescent bulbs will work with reversed polarity, but LED bulbs will not)
• For use in Classic vehicles with built in turn signal switch
• For use in Class 8 trucks (see diagram shown in photos)
• Must update relay when converting from incandescent to LED
• Original incandescent flasher will burn out and/or turn signals will flash too fast

 

I put LED's into my '57 tail lights and left the incandescent in the front. Works great with regular flasher.

 

update... Jan 16th.
I reversed the jumper wires feeding to the LED flasher relay. The LED flasher started to work ONLY on the right side with the incandescent bulb. This proves it was polarity sensitive. I tried the LED flasher on the left side blinkers and still would not with all LED bulbs and with the jumper wires reversed.
The grote flasher unit is designed for 1 amp to 20 amps. One 1157 incandescent bulb pulls 2 amps approx. That's why the LED flasher will work on the side with the incandescent bulb when I reversed the jumper wires to flasher.
On the left side with all LED's between the front 1157 LED bulb (.2amp) & back 1157 LED bulb (.2 amp) and 2 side marker LED bulbs approx. .1 amp each for a total of .6 amps - .7 total, isn't enough to allow the LED relay to work. I have come to realize that I need an LED flasher that starts at .1 amp and may need to reverse the pins possibly.
Two different automotive shops have sold me 2 different types of LED flashers and said they will work, well they don't for my application.

 

Update Jan 19th revised....
I ordered 2 Led Flasher 2 prong Relays. .1 watt to 150 watts, reversed the polarity on the flasher relay under steering wheel left side, works great with no issues using all LED bulbs. It doesn't click when it flashes, not that it matters as I can't hear it anyways with my exhaust. (: The led bulbs all flash correctly.

Revised Jan 20th .... I found an issue,,, when I pull my parking lights on or full head lights, the blinkers on either side with all LED bulbs will flash very dim... everything works perfect no with running lights or head lights on. I put a incandescent bulb in, everything works fine with the parking lights or head lights on.
Trying to understand what the difference is when the parking lights are on with the LED bulbs. Polarity sensitive using a different circuit?
Any ideas ....?

 

Who was the manufacturer and what was the part number of the flasher that worked for you?

 

MGI Speed ware

Have malfunctioning blinkers after installing LED signal lights? This hyper flash issue is caused when a thermal relay is connected to a low current consuming LED signal.
The fix? An electronic signal relay will make sure your lights flash at a normal rate. This 2-pin, completely silent electronic relay also works with regular filament type bulbs up to 150W.
To install your new relay, simply disconnect and replace the OEM 2-pin flasher.

This 2-pin flasher relay will NOT replace a 3-pin relay.

Specifications
• Wattage: 0.1W-150W
• Operating Voltage: 12V
• Lifetime: 400 working hours
• Dimensions: 1.2” x 1.2” x 1.2” (30mm x 30mm x 30mm)
• Includes 2 x flasher relay

Why Buy MGI

We pride ourselves in delivering quality products at a superb price — Whether you're looking to revamp a classic muscle car, give a personal touch to a new vehicle,
or prepare a custom build for the big race, MGI automotive accessories will help you speed across the finish line.

Because FAST starts with MGI SpeedWare

 

I am running into the same issue myself on my 83 Delta and yet to find a solution. I purchased the non-polarity version of these flashers to bypass a reversal kit after testing the power/ground to find that the older cars are wired backwards. These are the products im running.

Flashers:
Taillight:
T/S:
I just tested mine, LED taillights signal fine with parking lights on/off ONLY when T/S lights are incandescent. And vice versa, LED T/S light signal fine with parking lights on/off ONLY when taillights are incandescent.

For now im running only my LED's in my taillights but if anyone has a wiring/flasher solution it would be greatly appreciated.

 

I wonder how many people have $$$ sitting on their work benches from LED bulbs, flashers, relays, etc. that won't work in their classic cars? I tried on both my '70 Nova & '78 Trans Am. Finally surrendered. Haven't even considered it on the Cutlass.

 

What is the great advantage to using LED bulbs? These cars were designed for 1157 incandescent bulbs and they seem to work just fine. I understand if you have a older 40-50's car that has small hard to see taillights that a person would want to put brighter bulbs in the tail lights,so hopefully you don't get rear ended by a texting kid-( another story). But the tail lights on our 60-70's and newer cars seem to be pretty big. 75 Cutlass has a big tail light.

 

The only sure-fire fix is to use a 3 wire relay - the type that have the normal two pins plus a separate ground wire. That lets them run real logic in the flasher without relying on the lights to provide a ground.

I went LED in the tails for precisely that reason - much, much brighter. I also added relays because the current draw was killing the dash, and definitely need a "smart" flasher to drive relays.

 

Thanks for posting this Tuffnut. I just started researching the archives for the same issue and to find out if anyone has any experience with swapping to LED dash light bulbs.

Mine is a 66' Toronado. I just received a sequential light module kit #90656, (6) 1" red LED tail light bulbs # 911-31022 (Alt. #1157,) & a (2) prong flasher for LED #910-64110. Just about to wire it in and this discussion is a big help for potential issues that might come up.

In refurbishing the dash gauge cluster, I was thinking about swapping the #68 Sylvania bulbs (pictured Left) with White LEDS.(pictured Left. However, I have read the same thing where and LED will not draw enough power.
My goal on both the tail lights and dash lights is to have them brighter, not just for me, but for driver's behind me. The stock #1157 tail lights on a Toronado are not that visible in the first place IMO, or it's because of the density of the lenses, or my old age.

Anyway, anyone that has experience with these and can share would be greatly appreciated.

Incandescent to LED Dash Bulbs


Thanks

 

Dash conversion to LED is simpler - there's no flashing - but with two caveats:
1) Dimming probably won't work. You need a special dimmer module that actually pulses the LEDs, but those usually have their own ****, etc etc
2) An LED can't provide enough current on the alternator excite circuit, which just so happens to be the charging warning light. You can add a high wattage resistor in parallel to the LED to make it work though.

 

Great point. I've not seen this warning in any thread about changing dash lights to LEDs. The easiest solution would be to not replace the charging warning light with LED. That light only comes on at start, so there's no life or other advantage to changing it out.

 

Great insight oddball-thanks. Should be easy to test run in a dark garage to see if there's a significant difference between the two.
i know it's old school having the charging warning light stock and operational, just going to see if it's worth it.

 

I appreciate that as well VC455 and will leave it in there to see how it acts.

 

What I find hilarious is old alternators need quite a bit of current on the excite, so they need a bulb or can be directly wired to an IGN circuit.

Meanwhile, the latest alternators from GM? Definitely the AD, maybe some of the CS series also, will fry the regulator if you connect the excite directly to IGN. So if you're retrofitting, you HAVE to run a bulb, a resistor bypass, or use a resistor inline if going straight to IGN.

 

Great info... I will be changing my warning light back....
Thanks

Jeff

 

Thanks for putting that info out oddball. I hope to test the LED dash lights against the stock incandescents this weekend and will post some pics if they come out okay. Don't like the idea of loosing dimmer control though and going through the extra work you mentioned.