North American Turbocoupe Organization



LEDs and Cruise Control operation
anasazi4st Offline
Senior Member
#1
I wanted to share an issue that has been bugging me for some time, and I finally found a solution to it: since the LED installation several years ago, the Cruise Control shuts off when I signal to change lanes on the highway. It’s very annoying, and while I would hit the RESUME button, it’s still distracting (I like to have everything just so). If you switch to LEDs from the original incandescent bulbs you will likely have the same issue as well.

And I would heartily urge that you DO switch to LEDs. The benefits are: less power drain, brighter white light, cooler temperatures of operation. In my experience it really doesn’t matter what the country of origin is, especially nowadays—I would suggest Amazon, though, so you’ll receive them from a more reputable manufacturer: read the reviews from other buyers. I’ve had ZERO problems with mine since I got them—again, about 3 years ago.

Backstory: After replacing the incandescent bulbs by installing LEDs in my Turbo Coupe, I found a lot of “bugs” that had to be worked out. For one, both the “Low Beam Out” and “Rear Lamp Out” warning indicators in the System Sentry came on and would not go off. As Jeff (Korn) has suggested, simply putting black tape over the indicator or, better yet, removing the LED/warning lamp has solved that problem. But this other issue didn’t seem to have as simple of a fix. Well, after a lot of Internet research I found the solution, which is also simple.

Replace the LEDs you just put in the High Mount Stop Light with the original incandescent bulbs. Problem solved, no more Cruise Control cancellation.

I found this answer on several truck and SUV websites, but there was no explanation as to why it would work (“The brake lights don’t come on when you use the turn signals, so how would changing the bulbs in the High Mount Stop Light work?”). One site in particular—dedicated to Honda Element owners—was particularly helpful, with easy to understand explanations of how the system worked and the solution. That site can be found Here.

Here is an excerpt from the first post in the thread, for those who don’t want to or can’t click on that link. This is from the elementownersclub.com website, as linked to above. The OP (Original Poster) is ai4px.

“I just installed LED taillights (brake lights), and my cruise stopped working. Or it would work and cancel after 5 to 20 seconds. I replaced one brake light with a standard incandescent light, and the cruise went back to working.

What I discovered is that LED taillights do not "pull" the 12v brake wire to ground as incandescent lamps do.... it has to do with LED's having a voltage drop of 1.2 volts. So this causes the brake line to "float" at 1.2v instead of being either at 12v or 0v. This "gray area" is enough to trick the cruise control into thinking you have hit the brakes. The solution is to make sure the brake line goes all the way to 0v when the brakes are not pressed.

There are two ways to do this. Make sure that ONE of the brake lights is incandescent. The best looking (most symmetric) is the 3rd brake light. 

Another solution is what I did. Wire a 10k ohm resistor across the LED lamp for the 3rd brake light. I got my lamp from superbrightleds.com , and the plastic body has little holes in it. I was able to thread a 1/4watt 10kohm resistor into the body and simply bend the leads down just like the wires that were already on the lamp. Works like a champ. Best of all, I didn't have to splice the load resistors (which get very warm) into any of my wires.”

And there you have it. I replaced the LEDs with the original incandescent bulbs in the High Mount Stop Light, and road tested it. Fixed!
Another proud dues-paying member.

1987 Turbo Coupe w/T5OD, 8.8 axle, grey smoke; most options. Got it in 1991 with 41K miles: 3 turbos, 2 heater cores, 3 T5OD full rebuilds, 6 clutches, 1 head gasket, 2 Teves II ABS units, etc. later....
dolphin1, 88chickentc and Mikey97D like this post
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spittinfire Offline
Member
#2
I wonder if adding a resistor would be enough to fix the sentry system problem as well. I know lamp out warning light problems are common when switching to LEDs because the system doesn't see the voltage that it does with incandescents.
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