LED equalizers/resistors -- what is adequate and safe installation?

[BonzaiDuck]

I assume that many Garage forum members post and read threads in the computer forums, particularly "Cases and Cooling", in which there are always discussions about which might be the best thermal paste or thermal adhesive to use for electronic parts.

I pursued my quest to install all LED lights for my side-marker, parking, brake, back-up and signal or cornering lights. I wish I hadn't pursued it, but it's almost done to my satisfaction. The LEDs cost too much. On an old car, like my 95 Trooper, there is a phenomenon called "hyper-flashing". Turn signal and hazard flashing lights can be a problem, since the car computer doesn't detect an adequate load from the signal lights, causing them to flash frenetically, and this can also interfere with cruise-control, the auto-trans shift-lock solenoid or switch, and other features.

For brake, parking, backup and stop lights, there doesn't seem to be a problem. But the signal lights are a different matter.

So . o o o o. . . . I discovered, in addition to the Tridon/Novita turn-signal flasher switch that I installed, that Sylvania produces these "equalizers". They are resistors, designed to make the car "think" there's a normal load on the flasher circuit when the turn signal or hazard lights are being used:

Sylvania LED Equalizers

One would install one pair each for the front and rear turn-signal lights.

The Load Equalizers have an aluminum heatsink, as shown in the Amazon picture. They generate a lot of heat, and users are warned to install them so they contact body metal to dissipate the heat.

Most of the You-Tube installation videos I've seen demonstrate the use of sheet-metal screws to make this installation.

I don't see why I shouldn't use a good two-part thermal epoxy after sanding paint off the body-metal surface. Finding a place to put the load equalizers can be troublesome, with few alternative positions -- for instance, near my front parking-light lens assembly. Getting a drill to work in such tight and cramped spaces is also problematic.

Does anyone see any kind of problem with sanding a metal surface to bare metal and affixing the load equalizer with an epoxy such as this?

Thermal epoxy from Newegg

I just cannot have those load equalizers coming loose and bouncing around with the other wiring. I know the misery of having short circuits in an automobile -- from the time I had a battery cable's insulation melt when it contacted the engine of my 64 SS Impala. Nasty business!

 

[NutBucket]

https://www.amazon.com/Alla-Lighting-Electronic-Flasher-Related/dp/B07GNXL7PF

Not that exact one per se but basically a solid-state relay. Why band-aid the problem when you can just fix it properly?

 

[BonzaiDuck]

https://www.amazon.com/Alla-Lighting-Electronic-Flasher-Related/dp/B07GNXL7PF

Not that exact one per se but basically a solid-state relay. Why band-aid the problem when you can just fix it properly?

You are absolutely correct about "Band-Aid" fixes.

I had already replaced the flasher switch/relay with this, from Rock-Auto/Pep-Boys:

Tridon/Novita Turn Signal Flasher EP34 or EP34C

There is potential confusion, in that this flasher switch is located on the driver-side fuse-box in the passenger compartement -- below the dashboard. There is also a "cornering light" or turn-signal "relay" in the engine compartment fuse-box. The pinouts for that relay are different, and your recommendations match the one I've already replaced.

On other recommendations from an O'Reilly's Auto Parts employee, I bought these load equalizers shown in my original post.

With no mention of the Novita flasher, other car-owners were complaining about adverse interaction between Cruise Control etc. and the LEDs. In my case, I noted the following symptom. When the Trooper is in "Park", the clicking noise you usually associate with the dashboard turn-signal indicator is about three times louder and coming from two locations -- the second location is under the auto-trans shifter console between the driver and passenger seats. Further investigation shows that the console cover hides a shift-lock controller, shift-position sensor and a shift-lock solenoid. If I shift into neutral and back to Park again with foot on the brake, the sound goes away. When I lift my foot off the brake pedal, the sound returns. Of course the brake switch is integrated with the auto-trans shift-lock: you can't move the shift lever unless the foot is on the brake.

I mentioned this to the auto-parts employee, and he recommended the load equalizers, even as I told him about replacing the flasher with the Tridon-Novita unit.

Maybe you have some more insights about this. I was getting ready today to go to the garage, remove the taillight and front corner light lenses, and go to work. If I install the equalizers, it will have no adverse effect, but the flashing will likely have a reduced frequency from what it is, in turn less than it was without the Tridon/Novita but more than originally.

 

[NutBucket]

A quick glance says that flasher supports LEDs....so why are you investigating resistors?

I highly doubt there's any single control module that connects/controls all the systems you mention in your car.

The reason you need a resistor is old "thermal" flashers rely on proper current draw to control the flashing speed. https://auto.howstuffworks.com/turn-signal2.htm There are still plenty of cars sold today that use thermal relays....because they are cheap and reliable.

EDIT: After reading your additional comments, I guess that would have to be quite vehicle dependent. A "dumb" light relay in the fuse box doesn't care what the current draw is. I find your observation quite interesting.

 

[BonzaiDuck]

A quick glance says that flasher supports LEDs....so why are you investigating resistors?

I highly doubt there's any single control module that connects/controls all the systems you mention in your car.

The reason you need a resistor is old "thermal" flashers rely on proper current draw to control the flashing speed. https://auto.howstuffworks.com/turn-signal2.htm There are still plenty of cars sold today that use thermal relays....because they are cheap and reliable.

EDIT: After reading your additional comments, I guess that would have to be quite vehicle dependent. A "dumb" light relay in the fuse box doesn't care what the current draw is. I find your observation quite interesting.

Anyway, my options at this point are these:

1) give up on having LED turn-signals -- replace them with the original 1156 (rear) and 1157 (front) light bulbs, leaving the brake/stop, backup and parking light LEDs in place.

2) Try the Alla flasher unit and observe

3) Go forward with the Sylvania load equalizer installations

(3) brings me back to my original question: What would be wrong with using the two-part thermal adhesive to affix the resistors, as opposed to screws?

Restoring this old Trooper has got me entangled in a lot of tedious, seeming unnecessary tasks. The other day, I repaired the spare-tire cover -- a naugahyde/vinyl-simulated leather fabric. It was 24 years old, and looked like s***, with the stitching split and unraveling. I used a can of "Mothers vinyl/plastic Restorer" and it looks like new. Then took a sail-making needle and heavy-duty thread to repair the stitching. My hands! My hands! They are f***ing SORE! But -- it looks brand new! One more detail: the "Isuzu Trooper" lettering needs silver vinyl paint touch-up with a Q-tip application. People who know I'm doing all these things will think I'm totally nuts . . . .

UPDATE: I'm going to examine the circuit diagrams again, but I'm always exploring "intuitive leaps". To reduce the amount of work and repetition -- or avoid stripping the screw for the rear taillight lens -- I'm going to test the brake/stoplight with a regular bulb replacement first*. I was planning to remove the lenses anyway to replace the foam rubber weatherstripping. Then, the next step if that one fails, would be to pull the front lens on the same side, replace the flasher LEDs with bulbs, and test with a single turn-signal switch position. After that, I have the remaining choices I mentioned.

I'm not too savvy about electricity -- went as far as freshman physics and special-relativity. Amps x Volts = Watts. Resistance, heat, etc. Parallel versus serial, etc. Eventually, this should all be sorted out -- maybe accompanied by pulling the lenses only once and reinstalling them.

* If depressing the brake and releasing it causes the extra clicking noise, I could suspect the LED brake-light replacement. That would only be two LEDs to replace, as opposed to four turn-signal LEDs.

SECOND UPDATE: BINGO! It was the brake switch and the stop-lights! Symptom Gone!!

SOMETIMES -- INTUITION SAVES THE DAY! The brake light and directional lights are wired (I think) in parallel to the same ground. I'd have to check the diagram for more insight, but that's . . it. The shift-lock solenoid should make one, single, solid "click" when the brake is depressed. Now -- it does -- only that. The directional signals have no effect on the shift-lock solenoid.

SooooooOOO! I only have to replace the rear stoplights with regular #1157 bulbs. Done!

Too bad I bought the resisters for $15 per pair. Then again, I could wire a pair of them into the stoplight circuit instead, and go back to LEDs. Maybe . . . . a small project for later, since removing the wrought-iron tail lens protectors and the lenses, then adding the weather-strip, was downright effortless with no damage to the taillight lens thread hole.

I almost want to thump my chest and say "Only I can fix it!" [heh-heh -- a little "P&N" there . . . ] Only had to replace 2 out of 12 bulbs, and not the signal/flasher lights! Only had to remove two plastic lens assemblies, as opposed to four! DONE!!

 

[mindless1]

Thin body sheet metal, especially steel, is a relatively terrible conductor. I'd throw them on an old computer/etc heatsink and screw or strap that *anywhere* else. You can calculate the heat based on the ohms and voltage and get a rough idea how much heatsinking it needs.

It might need nothing more than a scrap of plate aluminum, and if you use a plate then both sides are flat so not only can the resistor be heatsunk to it, but also it can be heatsunk to whatever you mount it on (if necessary).

If you want to use thermal adhesive instead of grease, it should be fine, but you must have a very clean structural piece that can not flex. Thermal adhesive would be a bad choice on thin sheet metal (but see above why not to mount there), it could pop off.

Since I would not mount on sheet metal, there would be no problem for me to drill holes somewhere else convenient and use screws too.

Also, the epoxy you linked is expensive for what it is. I'd sooner go for Arctic Silver Alumina Epoxy which is about $12, or investigating further I'm sure I could get a larger quantity of something else for $20 or less... not that you necessary need more, and it does have a shelf life so new old stock should be avoided.

 

[Fallen Kell]

I pursued my quest to install all LED lights for my side-marker, parking, brake, back-up and signal or cornering lights. I wish I hadn't pursued it, but it's almost done to my satisfaction. The LEDs cost too much. On an old car, like my 95 Trooper, there is a phenomenon called "hyper-flashing". Turn signal and hazard flashing lights can be a problem, since the car computer doesn't detect an adequate load from the signal lights, causing them to flash frenetically, and this can also interfere with cruise-control, the auto-trans shift-lock solenoid or switch, and other features.

For brake, parking, backup and stop lights, there doesn't seem to be a problem. But the signal lights are a different matter.

So . o o o o. . . . I discovered, in addition to the Tridon/Novita turn-signal flasher switch that I installed, that Sylvania produces these "equalizers". They are resistors, designed to make the car "think" there's a normal load on the flasher circuit when the turn signal or hazard lights are being used:

A quick glance says that flasher supports LEDs....so why are you investigating resistors?

I highly doubt there's any single control module that connects/controls all the systems you mention in your car.

The reason you need a resistor is old "thermal" flashers rely on proper current draw to control the flashing speed. https://auto.howstuffworks.com/turn-signal2.htm There are still plenty of cars sold today that use thermal relays....because they are cheap and reliable.

EDIT: After reading your additional comments, I guess that would have to be quite vehicle dependent. A "dumb" light relay in the fuse box doesn't care what the current draw is. I find your observation quite interesting.

It all has to do with the car's circuit design for the flashers. Many cars used a very simple oscillating design that the load of the lightbulb was a part of the calculation as to why it works. With the much higher efficiency of the LED bulb, the load value drops, which causes the resistance values to the capacitor in the circuit to be lower than originally calculated. This means that the capacitor charges up faster than originally designed and hits the charge level where it triggers the circuit to switch from charging to discharging (and thus opening and closing the circuit for electricity to flow through the light), meaning it will blink on and off faster. Here is an example of this type of circuit (cars would obviously be using a different voltage level of around 14V, which does cause a change in the required resistance and capacitor values of the circuit, but as I said, this is just an example):
https://electronics.stackexchange.com/questions/157960/blinker-circuit-theory?rq=1

The reason for adding a resistor in series with the LED is to more closely match the original resistance value of the old lightbulb, and thus allowing the capacitor to charge at its previous calculated pace. (For those that don't really read circuit design, R = resistor, C = capacitor, Q = transistor. They will typically have a number like C1, C2, C3 to identify the individual items in the design and a value (for capacitors, it is typically micro-farads, resistors it is typically ohms, transistors usually give a model/type).

 

[BonzaiDuck]

Many thanks to Fallen Kell and mindless1 for their contributions.

The flasher switch/relay in the cockpit fuse-box seems to take care of the signal and hazard "hyper-flashing", but it interacts with whatever senses the load on the stoplight. When the stoplight is "off", apparently something causes the shift-lock-solenoid to "click" with the frequency of the signal flashing.

If I replaced the stop-light/tail-light LED with a standard white #1157 double-filament bulb, this behavior of the solenoid goes away. Therefore, I should think I should splice in an LED equalizer-resistor to the stop/brake-light circuit -- IF -- IF -- I replace the #1157 bulb with its LED equivalent -- again.

I understand that sheet steel is an unhappy thermal conductor, but the advice about these resistors is to use exactly that for contact with the resistor -- the sheet-steel of the body. The problem with the epoxy mostly arises with some future need to remove it. My understanding is that these equalizer-resistors have a very long life, and if I no longer wanted to splice it into the brake-light circuit, I would simply sever one of the two wires from the resistor. The resistor can stay affixed to body metal indefinitely, whether I use it or not.

But there is certainly no urgency to replace the currently-installed #1157 bulbs with LED. As I said -- of the 12 bulbs in the tail-lights and front corner light assemblies, I've replaced 10 with LEDs, and the two remaining #1157 bulbs should last a good long time. They're not going to impact power-draw too much, since the bulbs are only used at night and when the brake-light is activated by the brake switch.

I even hear from some tech veterans that despite the reputation of low power-draw, brighter lighting and greater longevity, that these LEDs can still occasionally go south.

The other thing I've yet to investigate after this learning episode also has some potential complications: the replacement of Halogen headlights with LED equivalents. While I could certainly wire in a set of LED Fog lights and just as easily use a separate harness/relay/switch-and-fuse instead of the wiring harness already in the car, the headlights may not be a simple matter.

 

[NutBucket]

The issue with LED headlight "upgrades" is the same as with HIDs: the beam pattern will be different since the light comes out of the bulb differently than a halogen. Just don't do it. You could try a bulb like a European Philips NiteBreaker (eBay is your best source) for more output from a halogen.