IRD ignition wiring


2018/2019 Unity CB
To avoid clogging up another thread, I'm posting the question here after not seeing anything with search. I want to install a manual switch on my IRD so that I can turn off alternator charging at times. I saw another install that had this switch on the passenger seat outboard side but that seems hard to use.

I ordered a lighted rocker switch off Ebay that I can snap into the Mercedes instrument panel. Looking at my schematic, the IRD has a blue wire labeled "To Ignition in Drivers Pedestal". What exactly is the "drivers pedestal" (does that mean under the drivers seat?)

Basically asking if anybody has traced the blue wire and the easiest way to run a wire from the IRD to under the dash, i.e., should I start under the passenger seat or the drivers seat for the easiest path?


2018 Unity MB
This doesn't answer your question about the wire run, other than the blue wire connects to a post under the driver's seat.
I installed on the outboard passenger seat, right beside the other switches, because there was plenty of room for the switch (I used a round switch that secured by securing a thin nut from inside the seat, not the snap-in switch type). I used this location because it was the easiest and had a short wiring run and easy ground. Hole cut with Drlll/Forstner bit. The switch is very low profile, and I don't think it would be easy to accidentally flip the switch.
My logic was also that I would not be turning on/off alternator charging except prior to engine starting, so the location was not a detriment to me. I didn't think it was probably a good idea to flip this switch on/off with the engine running, but this was simple farmboy logic, not based on any engineering knowledge.


2018/2019 Unity CB
That makes sense. That panel would be my fallback position. But I'm thinking the switch on the dash if it's not much work. The light would remind me if it's on or not.

The other reason is I was thinking to wait till geting on a highway or main road.

I'm pretty sure that based on what the IRD does it would be perfectly fine to switch on and off at any time, or for that matter switch the output of it instead.

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2018 Unity TB
I installed the switch (a Blue Sea Contura) on the inside of the passenger seat so I can easy control the alternator changing while driving. If I expect my solar will be sufficient to charge my batteries, I want the alternator off. Other times, if the alternator is needed to help charge the batteries (and power the coach), I can switch the alternator on and then off when no longer needed. But, except at night, I generally do not continuously run the alternator. With the alternator on, once the batteries are fully charged and my solar controller drops from bulk voltage to float voltage, the solar output stops (because the float voltage is lower than the alternator voltage). When this happens, I switch the alternator off until the batteries discharge a bit and the solar controller goes into bulk mode; then I can turn the alternator back on and still use the solar output. This all probably sounds more complicated than it is in practice, at least for someone me who periodically checks the solar output and battery charge state.

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