LED tail brake lights and flashing glow plug light

Zheking · Feb 20, 2019

LED brake lights and flashing glow plug light - adding resistance

Put some led brake lights in and got the flashing glow plug light. Rather than installing resistance at the back by the lights or dummy light, I ordered a new brake pedal switch and I'm just going to install an internal resistor in it. Problem is, after looking through the FSM I just downloaded (these are much much more difficult to navigate through than the nissan ones i'm used to), I can't seem to find which pins / wires are for what. I found voltage specifications, max resistance ohms, and a few things like that.
Does anyone who's a little more well versed in the FSM know which pins are what?which ones the resistor will need to go between that's monitoring the brake lights? labeled 1,2,3,4 on the outside, and obviously on the back side they're going to be opposite.

arniewallace · Feb 20, 2019

Fit a relay, with an internal diode in it, at one of the rear lamp units. The lamp units have male terminals on them, so you can use small female recepticals to attach the relay. I done it to both my Golf and Bora (Jetta) and it works like a charm and stops the flashing glow lamp and the ghosting on the rear high level brakelamp.

Mike_04GolfTDI · Feb 20, 2019

I tried LED tail lights once and to stop the flashing glowplug light all I did is solder a 1/8 watt (because they’re very small) 10,000 ohm resistor between the contacts on the bulb. The bulb could still fit in the socket because the resistor was small and not in the way.

The ECU only needs to see continuity at the bulb and very little current needs to flow. I’m pretty sure it was 10,000 ohms that I used, but if that doesn’t work try 1000 or lower. The higher resistance you can get away with the better so it doesn’t heat up or waste power.

Also your cruise control won’t work if the brake lights are burnt out, or the ECU thinks they are because they’re LED.

I eventually removed my LED bulbs because they were dim. This was years ago and they are probably better now.

I also recall there was an issue with the flasher module flashing rapidly with LED signal bulbs. There’s a modification you can make to the flasher unit to prevent that. I was never successful doing that mod because of variations in flasher modules. Mine wasn’t the right one for the instructions that I found by googling.

Zheking · Feb 21, 2019

Mike_04GolfTDI said:
I tried LED tail lights once and to stop the flashing glowplug light all I did is solder a 1/8 watt (because they’re very small) 10,000 ohm resistor between the contacts on the bulb. The bulb could still fit in the socket because the resistor was small and not in the way.

The ECU only needs to see continuity at the bulb and very little current needs to flow. I’m pretty sure it was 10,000 ohms that I used, but if that doesn’t work try 1000 or lower. The higher resistance you can get away with the better so it doesn’t heat up or waste power.

Also your cruise control won’t work if the brake lights are burnt out, or the ECU thinks they are because they’re LED.

I eventually removed my LED bulbs because they were dim. This was years ago and they are probably better now.

I also recall there was an issue with the flasher module flashing rapidly with LED signal bulbs. There’s a modification you can make to the flasher unit to prevent that. I was never successful doing that mod because of variations in flasher modules. Mine wasn’t the right one for the instructions that I found by googling.

If it only needs to see continuity you can just put a piece of wire between them with no resistance. and it has continuity with an LED bulb, so I definitely think there's a resistance factor needed.

I got a new flasher relay for $20 to prevent the hyperflash from led turn signals. there's a guy selling them now. It was easier than trying to do myself, I'll pay for convenience.

also, turns out it's pins 1 & 4.. well technically it's pin 4 to ground, but that isn't possible, I put a 1k ohm resistor between 1 and 4, cleared the code, and it worked, about half way to work (15 miles or so) it came back on though. I'll pull the switch back out and see if the resistor broke or what the deal was. First resistor i put in broke after reassembly due to space issues, so who knows.

Mike_04GolfTDI · Feb 22, 2019

Well the reason you wouldn't use just a wire instead of a resistor is because too much current would flow and the wire would melt, or a fuse would blow.

LED's have continuity in one direction. They're diodes. It's what they do (and they emit light).

Zheking · Mar 6, 2019

after sitting down and looking at the switch more, the only place to put a resistor is on the bottom portion, since the switch is NO, a resistor closes the switch, but when the brake pedal is pressed it closes the switch leaving no resistance. I'm sure if someone got real crafty with their soldering and bending of resistors, they MIGHT could do it, but I just threw one in the back and was done with it.

phaser · Mar 6, 2019

For A4's, disable the low voltage sensing circuit (#7 pin) contained in the emergency flasher switch, and problem solved.

Read through this thread: http://forums.tdiclub.com/showthread.php?t=296614

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LED tail brake lights and flashing glow plug light

Zheking

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arniewallace

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Mike_04GolfTDI

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Zheking

Well-known member

Mike_04GolfTDI

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Zheking

Well-known member

phaser

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