Audiovox Cruise Control & Strobe LED Brake Lights - Don’t Play Nice

[STlicious]

So I’ve been running by 2005 ST1300A for 11 years with the Audiovox cruise control. I decided to upgrade my brake lights to LED bulbs that flash when brakes are applied. I fully expected for these bulbs to interfere with the functioning of the cruise control as I remember it being talked about years before in one forum or another. I wasn’t disappointed and now the cruise control will not engage. I know the fix involves the use of a relay that isolates either the cruise control or the brake lights until the brakes are engaged (I am very fuzzy on the specifics). So if anyone with more reliable brain cells on the specifics of the type of relay, placement and how it needs to be wired could spell it out for me, I’d be much appreciated.

 

[Igofar]

I think your going to find its the cheap made in China bulbs that are causing your cruise control to turn off.
This is a common problem for Goldwing's as well.
The bulbs bleed over and the bike thinks the brakes are activated and turn the cruise control off.

 

[Larry Fine]

It's actually a little different. The cruise control uses the brake light as a cancel signal, and "monitors" that connection by looking for the purple wire to be grounded through the brake-light bulb filament when the brake light is off. LED bulbs don't conduct well enough when off to effectively ground the purple wire.

The solution is to use a small 12v relay (it need not be a typical 30a relay) to ground the purple wire when the brake is not being applied. So you need to use a normally-closed (or the NC contacts of a double-throw relay) with the coil wired to the brake-light wire, so the purple wire is ungrounded when you hit the brakes.

 

[STlicious]

It's actually a little different. The cruise control uses the brake light as a cancel signal, and "monitors" that connection by looking for the purple wire to be grounded through the brake-light bulb filament when the brake light is off. LED bulbs don't conduct well enough when off to effectively ground the purple wire.

The solution is to use a small 12v relay (it need not be a typical 30a relay) to ground the purple wire when the brake is not being applied. So you need to use a normally-closed (or the NC contacts of a double-throw relay) with the coil wired to the brake-light wire, so the purple wire is ungrounded when you hit the brakes.

That’s exactly what I was looking for. Thanks for the help. I’ll get back to post how adding the relay works.

 

[mlheck]

+1 on Larry's post. I had the same issue when I went to LED's. The relay fixed the issue.