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Coach Multiplex Lights Not Working Properly - Solved by using LEDs

Frank McElroy

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Offline I’ve been helping Doug with a new to him 2009 Beaver Patriot Thunder and I want to share the following with the group.  Sorry for the long post but there is a lot of technical information to cover.

When Doug turned on his Living Room Lights, all was fine. BUT when he also turned on other lights like the Dinette Lights, after a few minutes, the Living Room Lights would go out and come back on with the cycle repeating.

The purpose of this technical post is to share how we identified the root cause of the problem and to explain why changing form factory halogen light bulbs to LED lights will solve this problem.


Monaco house multiplex lighting systems used an Intellitec 000-00844-120 Module to control turning interior lights on/off and having the option to dim them.

This module has outputs to control up to ten sets of lights.  BUT, there is a maximum load rating of 120 watts for any single channel output and a total maximum of 224 watts for all 10 module output channels if all are on at the same time.  If you exceed these design limits, the module could go into an overload protection mode and shut down output channels.

In Doug’s case, Monaco designed his living room ceiling lights with 8 small 10 watt halogen lights plus 3 large 20 watt halogen lights. That adds up to 140 watts on a single channel designed with a FET (Field Effect Transistor) to only handle 120 watts (10 amps max).  The intellitec spec for the module is a maximum fuse of 10 amps per channel, but Monaco used a 20 amp fuse for the living room lights. 

If only the Living Room lights were on, everything worked but as soon as another set of lights associated with that same module were turned on the Intellitec module overloaded, overheated the output FET, and FET internal to the module went into overload protection mode and turned the lights off – when the FET cooled down, the lights came back on for a minute or two and then went back off and the cycle repeated.

To temporary solve the problem, I had Brett remove 3 of the large 20 watt Halogen light bulbs as part of the living Room light string and now all the lights in the coach stay on with no problem because the Living Room lights channel output FET now wasn’t overloaded.

LED’s use far less current that halogen lights.  As many on the group already have, Brett will be changing all his ceiling lights to LEDs.  If others haven’t, they should do the same both to save energy and to avoid overloading the Intellitec light dimmer modules.  This is especially true on high end coaches that may be at the max or above the FET output current rating of 10 amp max on any output channel.

I’m posting this to help others who may be experiencing similar issues and may not realize that the house Intellitec modules can be overloaded and result in lights turning on and off on their own as the module is trying to reset itself to prevent heat overload.

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I bought mine about 10 years ago.  Today there are a lot more options out there.  Just Google G4 dimmable warm color LED lights.

Maybe someone who recently bought them will chime in with a direct link.

When I replaced mine I used an old photographic light meter placed on the counter to measure luminance.  The specs on the LEDs were so close to the old halogens that the light meter really couldn't tell any difference in light brightness.  I had both 10 and 20 watt halogen bulbs and easily found LED equivalents.  So far, none of the LEDs have burned out.

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