LED Brake Lights

[69porsche]

Originally Posted by spoke

PM sent.

See PM for needed info...thanks

[Canada Kev]

Originally Posted by 69porsche

So Kevin, you did not have to solder any wires within the flasher is what I am reading from your post?

Sorry, I had forgotten that I purchased Spoke's flasher with my lights. My apologies for that.

[lipsurne]

I am also thinking to improve my car headlight. The thread I was looking for. Some solid information here how to do that.

[69porsche]

Originally Posted by Arne2

After reviewing your post, and thinking about how it must work, I decided that any of the 3 should be ok to remove. So I went with R3 because it was off by itself and easier to get the soldering irons on. Worked like a champ. The tail lights are still a bit brighter than the old incandescent bulbs, but there is more difference in brightness between tail and brake than before. I am totally happy with this change, but I'll keep the resistors just in case. Now back to replacing the tail light seals, a dirty job.

Before


After

Arne,
So in order to ensure there's a significant contrast between brake and tail light, you removed the R3---How's that working for you? and how were you able to remove the R3 and did it take any other skills or modifications to the existing board?

[spoke]

Checked the fit of the converter board on the back of the heatsink. Four of the inside row of screws for the LED board will be long enough to mount the converter board on. The further away the converter board can be from the heatsink the better.

I didn't quite line up the wires from the LED board to the converter board. They're off by 90 degrees. Should be ok. I'll put the wires in heat shrink tubing to protect it.

[spoke]

Originally Posted by 69porsche

Arne,
So in order to ensure there's a significant contrast between brake and tail light, you removed the R3---How's that working for you? and how were you able to remove the R3 and did it take any other skills or modifications to the existing board?

Gordon,

There's 3 identical resistors providing the current limit for the running lights. R2, R3, and R4. In the pic they're the smaller blue resistors. They're in parallel so removing any one of the 3 will reduce the running light current by 33%.

Unsoldering the resistors is best done with 2 solder guns/irons. Because there's a soldered pad on each side of the resistor, one solder gun/iron isn't large enough to span across the resistor to heat both pads to release the resistor.

With 2 solder irons, touch each pad with an iron and wait for the solder to liquefy. Once liquefied, just push the resistor to the side. Clean up any splattered solder with one of the irons.

The resistor can be replaced in the reverse order and adding a bit of solder to fill each pad.

[69porsche]

Jerry,
Just seeing this-Thanks. I might go this route once I get the flasher installed and see I f I want a more distinct contrast between brake and tail light
Gordon

[spoke]

Assembled the switching converter board for the driving lights and connected it to the LED board.

Seems to be working as planned. Total power is 21W; about 19W of that in the LEDs operating at 0.35Amps.

Will put it all together and do some temperature measurements. Outside of the case, the switching MOSFET is running about 55C above ambient. Will have to keep an eye on that.

[spoke]

Here's the converter board connected to the LED board. Fits nicely into the enclosure.

[spoke]

A couple of steps forward and a fried MOSFET backwards.

I was testing low voltage (10V) operation which is the highest MOSFET current and the FET melted. It also damaged the converter board beyond repair.

The melted FET is FQD7N10LTM with an ON resistance of 0.35 ohm. I'm considering using the IPD053N08N3GATMA1 with an ON resistance of 0.0053 ohm.

Will also replace the inductor which has 68uH inductance with .089 ohm series resistance. Looking at 47uH inductors with .02 ohm or 4x less resistance.

Also need to look for a thermal insulator to put between the converter board and the heatsink to attenuate radiant energy from the heatsink.

[RDM]

Originally Posted by spoke

So the brake and 3rd brake LEDs are on very dimly with the car shut off?

Do you have cruise control on the car?

During operation the cruise control senses the brake light wire and dumps several milliamperes into the brake light wire causing the brake lights to light dimly (during key on) even with the brake pedal not pressed.

Does the dim lighting decay over time? Like by the next morning?

This is interesting. If anything, the very high impedance of the LEDs isn't causing the leak but has allowed the leakage current to light them up when the car is off.

If you're into checking this out, it would be interesting to do a couple of tests:

1) With key off, disconnect one of the brake boards and see if the other LEDs get brighter.
2) With key off, disconnect one of the brake boards and measure the voltage from chassis to the brake button in the socket.

I finally had a chance to look at this. With the cruise control connected, I have 6.5 volts, ~0.2 mA through the brake circuit. Disconnecting one side changes the brightness on the other side only as long as the wires are being moved.

OK, so disconnect the main connector to the cruise to solve the problem, right? Wrong. Disconnecting the cruise makes the lights brighter, ~7.1 volts, and I couldn't get a stable current measurement because the light would flash bright, then dim, then out, then change again. Unstable. Weird. Here's video. https://drive.google.com/file/d/1qAHVqRoT_MCLYre56mnHZukLgD54reew/view?usp=sharing

Key off, no one in the car.

Ideas?

[spoke]

Originally Posted by RDM

I finally had a chance to look at this. With the cruise control connected, I have 6.5 volts, ~0.2 mA through the brake circuit. Disconnecting one side changes the brightness on the other side only as long as the wires are being moved.

OK, so disconnect the main connector to the cruise to solve the problem, right? Wrong. Disconnecting the cruise makes the lights brighter, ~7.1 volts, and I couldn't get a stable current measurement because the light would flash bright, then dim, then out, then change again. Unstable. Weird. Here's video. https://drive.google.com/file/d/1qAHVqRoT_MCLYre56mnHZukLgD54reew/view?usp=sharing

Key off, no one in the car.

Ideas?

Agreed; Weird.

You wrote:
Disconnecting one side changes the brightness on the other side only as long as the wires are being moved.

What do you mean "as long as the wires are being moved? You mean they flicker brighter when you jiggle the wires?

So disconnecting the CC ECU made the lights get brighter? Then the CC ECU was loading whatever is driving these lights.

On my '86 930, fuse 4 powers the brake lights. In this sheet, the wire exiting fuse 4 is the brake power lead. Find this fuse in your car maybe from a wire diagram or the owners manual. The brake lights are the only components on this fuse. Pull the fuse and see if the lights go out. Measure voltages on both sides of the fuse once pulled.

[RDM]

Yes, the moving wires I referred to was the plugging/unplugging process of the LED board. As I was doing that, the lights got dimmer/brighter, but once fully plugged in light output was constant.

I couldn't get the brake lights to go out by removing any single fuse, and I didn't have time to try combinations, BUT

Everything connected, key off.


With this fuse removed (labeled in the fuse box lid as stop lights)


The light brightens to look like this:


And unplugging the cruise ECU (with or without the relay unplugged), the lights further brighten like this:


Here's the wiring diagram for '81 brake lights.


I feel like I am getting further from understanding, not closer.

[spoke]

Originally Posted by RDM

I feel like I am getting further from understanding, not closer.

Yeah, electronics will do that to you. I can't tell you how many times some circuit issue has kicked my ass. I usually find a solution by just keep plugging away. Sometimes you have to walk away and do something else then come back to it. We're always on the look out for that "ah ha!" moment when the issue gets resolved.

Looking at your schematic, it looks like your car has different brake switches than my '86 930. See below where the 2 brake light switches on my car only have 2 contacts. So my switches are either open (foot off pedal) or connected to fuse 4 (foot on pedal).

In your car, the brake light wires are switched between power coming from fuse 15 (foot on pedal) or to where ever V24 goes to (foot off pedal). Can you find where V24 goes to on the schematic?

On my '86, the brakes do not come on when the car is off. Maybe yours is the same. If so, a quick test to see if what ever is at V24 is powering the lights with key off is to do this: With key off, press the brake pedal and see if the brake lights go out. You'll be switching brake light power from V24 to Fuse 15.

Also, if you pull fuse 15, the brake lights shouldn't come on with car on and brakes applied.

'86 930 Brake switches (red arrow)

[spoke]

Your '81 brake switches have 3 terminals.

[spoke]

More fun stuff with 911 wiring. There are a few first adopters of the front sidemarker boards doing installations.

For one of them, one side works ok but the other side won't light up although the standard bulb does light up.

After disassembling the socket and measuring the wires, it appears the voltage on the wires is backwards. Notice the measurement is -12.49V instead of +12.49V.

Question to those who have disassembled/reassembled the front bumper: How is it possible to reverse these 2 wires and how to fix this? TIA.

[spoke]

Here's the wire diagram for an '86 930 for the front sidemarker. It looks like the sidemarker gets its power from the front turnsignal on that side.

Can someone confirm how to get at these wires and is the connection of the sidemarker wires at the back of the front turnsignal bucket? How do we get at these wires?

[spoke]

The owner confirmed that the bumper was removed before for repaint. The shop may have reversed the front sidemarker wires during reassembly. Everything was ok with incandescent front sidemarker bulbs as the bulbs don't care if the center is positive or negative. LED replacement boards aren't so care-free about voltage polarity.

[spoke]

OK, problem solved. The front sidemarker wires were swapped when the bumper was reinstalled after a repaint.

First time I've seen this for a front sidemarker and interesting that it occurred during one of the first installations of this sidemarker.

This wire swapping has been observed several times for the 3rd brake light as incandescent bulbs light up regardless of voltage polarity.

[A horse with no name]

First...Thanks Jerry for helping me find out why my new LED park light would not work on the R side even though the original bulb did...After reversing the connections within the R signal light, the problem was resolved.

Now for the difference...Wow! - Genuienly 'day and night'- as usual- with the other LED light conversions that I have purchased from you!... No more not seeing the front end side anymore when driving or parked...I also like that you have provided another wire (red) on the board that I can use to hook up to my signal lights... I'm going to do this as it is a great feature to have...Very 'mod'

I guess that I can genuienly now say that my ride is not missing any more 'Spokes' eh!

Again, thanks for the fine products, including your help in resolving the issue that I had.
( New park light R hand side)