LED turn signal flash pattern

[Gastrap]

LED turn signal flashing characteristics

I've searched for a couple hours already, and didn't see this covered...

With incandescent lighting, my deuce turn signals and hazards flashed from bright to off. With front incandescent, and rear Grote LED's they functioned the same. Now I have installed the front Grote LED turn/park lights, and all 4 turn signals flash from bright to dim instead of bright to off. This is with the light switch in position 1 or 2 and park off. Parking lights work properly and all grounds are good.

Is this normal? I have the newest style flasher, and the flashing funtion is fine, just bright to dim. I though maybe this had something to do with the built in resistance in the grote lights.

 

[Suprman]

You may have switched a connection on one of the lights. The led lights require a separate ground also. I know on the 5ton the numbers on the harness for the tail lights match the numbers on the lights wiring but they are not accurate. Disconnect your back lights use a test light to figure out what is what blinker brake running lights it's a lot easier to troubleshoot them one at a time.

 

[Gastrap]

I'll double check. There are multiple circuit code numbers on each of the new lights, but each corrosponds with ones on the truck. 461,491, and 20. Have the ground run right to the frame, and park, blackout and flash functions work fine. Tail lights have been on for months, and worked fine until front LEDs installed.

 

[gimpyrobb]

You need a LED compatible flasher unit. The older ones don't work with them.

 

[Gastrap]

Got one. Flashes great, just goes from bright to dim instead of bright to off.

 

[Suprman]

Something has to be miswired I would check the rears first even though they appeared to work. The led lights were not designed for deuce or 5tons the numbers may match on the wires but they are not always the correct match. The test light will tell all.

 

[cranetruck]

Got one. Flashes great, just goes from bright to dim instead of bright to off.

What about your pilot light by the steering wheel, does it flash normally?

 

[Gastrap]

It flashes normally, just dimmer than before.

 

[Gastrap]

These fronts are some of the first Grotes, dated '06. I wonder If they dont play well with the newer rears? I remember a post that said they made some changes in '07. My flasher is a new SCR type dated '05.

I double checked the wiring, all plugged in correctly. Used test light to verify what wires were needed. Switched 461 and 491 just for kicks on the fronts. Then it just flashed beginning with dim (park) and then even dimmer instead of off.


Edited to add- flasher is actually dated '01, is P/N 19207-11613631, and is properly grounded. beginning to think this isn't right after all. Plug in the stock fronts and all is well again, rear LEDs work perfectly, like there's just not enough resistance to operate it without at least one regular bulb in the circuit. I thought I had the newest model flasher, and the place I bought it from advertises it as "Compatible with LED or incandescent lights or a combination of both"

 

[papakb]

Because the LEDs use so much less current to illuminate they will show any current leakage in the flasher as a dim light where incandescents wouldn't. That's where I'd begin TS this problem. As for "designed to work with", no matter who the manufacturer is the lamp specifications are for the lamp, not for the truck. The assigned stock number is a universal stock number applicable for any vehicle that uses this style composite light.

 

[cranetruck]

To solve the problem with poor flasher performance, leaky or sensitive to overloads, I wired in an electromechanical relay to handle the switching. Did this years ago and have since never had a problem with the flasher.
On the 8x8, I installed heavy duty relays, which also lets you hear them (click, click) in case you'd forget to turn them off.
The second relay is for the headlights, which now have a separate circuit breaker, so that the light switch CB tripping won't effect them.

 

[Gastrap]

Thanks for all the input.

I test wired in one incandescent in parallel on 460/461 and all 4 LED's worked perfectly. I ordered a new flasher of the same style. I suspect my 3 year old flasher has just developed a problem. Checked every terminal & wire and all grounds are clean and zero resistance to frame.

 

[Gastrap]

No luck with the new flasher, works the same. I did notice that if I remove the indicator bulb on the directional switch everything works fine. So it seems the power that drives this bulb is backfeeding to the lights through the bulb. Disassembled the switch to check for pinched or shorted wires, everything looks good in there.

Is the normal function of the bulb on the switch to flash out of sequence with the lights, or do they all cycle on-off at the same time when working properly ?

Off to search TM's for a schematic...

 

[Suprman]

Disconnect them all. Start with making sure they are all grounded well. Put the lights switch to headlight and the hazards on. Go to the back lights with your test light find the flashing one that is brake/turn and there will be one that is constant on that goes to the tail light running light. Just connect those 2 along with the ground and then do the same on the other rear. To to the front do the same thing there will be running light on constant and flashing for blinker. Don't go by wire numbers they don't always match up.

 

[Suprman]

Check the ground on the flasher itself also.

 

[Gastrap]

Even though I had eliminated any problem with wiring/grounds in the truck, I moved all components to the bench. With just one or two LED's, a flasher, direction control, and a power supply, the same problem persists and is still cured by removing the interior pilot light or adding an incandescent in parrallel. The pilot light is backfeeding the flasher through its filament. Control unit passes all bench tests in TM ( those are done with bulb removed.)

I've found that my pilot light in the control is not wired internally from H to ground as TM 9-2320-230-20 shows, but rather from H to F. If I wire this to ground all is well. This was why I asked if normally these lights flash in sync with the LEDs or not.