# 1990 e350 built by mcoy miller



## blackturbo (Nov 16, 2009)

Hello folks, 
        I just bought this ford ambulance to convert to a work truck. its a 1990 mccoy miller box, some people refer to it as level 3 or something like that. but its the bigger one and not the van. well anyway, right behind the drivers seat in a storage cabinet is all the electrical, relays,etc. theres a switch in there, looks like a standard wall switch in a house. what does this do? theres actually two switches, one is a breaker . my guess maybe a switch to the engine block heater, maybe somewon will know.. thanks..

mark


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## exodus (Nov 16, 2009)

It wold probably help if you took a few pictures.


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## medicdan (Nov 16, 2009)

I believe those are the main power breakers for the truck's systems (most in the back). They also tend to be a relay and failsafe if there is a short or surge in the shoreline connection. Pictures would, however help


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## MRE (Nov 16, 2009)

My guess is that it is a switch for the 110VAC outlets in the box.  These are usually powered by an inverter connected to one or both of the truck's 12V batteries.  When the truck is plugged into the wall (shore power) they are powered from that.  

My truck is an 03 McCoy Miller and there is a GFCI in the spot that you mentioned and it functions as I described above.


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## blackturbo (Nov 16, 2009)

*picture*

heres a picture, in this compartment there is loads of relays,wiring,etc. only two switches,, one breaker, and this one. below this compartment is where the inverter is. flipping this switch doesnt seem to do anything as with controlling the outlets..mystery switch  Also, do the wig wag headlights hook into the high beams? there some wires near the headlights disconnected.. there was one private owner before me that removed or disconnected emergency red lights and anything else flashing. thanks for all your help.


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## redcrossemt (Nov 16, 2009)

Hard to tell from your picture. It's obviously 110 volts. Could be for shore power disconnect, an inverter or individual outlet(s), block heater, or perhaps battery charger. 

Did they leave the inverter onboard?

I would be careful and not connect shore power to the truck before figuring out what has been done electrically. That means having an electrician look at the truck if you don't know. 

Shore power and/or inverters are as dangerous as home electricity... Not comparable to 12v DC at all.


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## blackturbo (Nov 17, 2009)

*switch*

No, the inverter was gone. I put in a 5,000 watt as a replacement (5,000 peak, and 2500 continous. I have already plugged to shore power and tried the switch, and nothing happens . The outlets remain charged regardless of switch position. I know all about AC and DC power so I feel confident with this new vehicle I have acquired. My guess its for a block heater, did all these mccoy miller boxes come with a block heater stock? Or was the block heater an option. There is a AC line under the hood with a female connector as the old owner said it was a power line when hooked up to shore. I havent tested yet if this line remains on with the switch. Maybe its for this. There is no type of battery charger, or 12 volt source other than the batteries. On RV's,, you usaully have a 12 volt power source other than the batteries when plugged into shore power. I might use this line under the hood to install a battery charger under the hood to provide 12 volt dc when plugged in so I dont have to run the motor to get 12 volt power or have the batteries on.   So far Ive spent a few hours with a volt meter and have figured out most of the electrical system. I was thinking this switch was common in this area and somewon could tell me what it was for. or maybe its something for the oxygen system that has been removed. Also, my friend said this thing was meant to idle for hours, is this true? He says real busy ambulances in busy places stay running 24/7 . this is my first diesel engine. The computer seems to control the idle, and idles up when theres a big load on the system. SOrry for all the questions, I never thought I would be driving an ambulance


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## redcrossemt (Nov 18, 2009)

blackturbo said:


> Also, my friend said this thing was meant to idle for hours, is this true? He says real busy ambulances in busy places stay running 24/7 . this is my first diesel engine. The computer seems to control the idle, and idles up when theres a big load on the system.



Diesels in general do a good job staying running for days on end. Many ambulance services keep their trucks on for 12-24 hours straight at a time, sometimes 24/7. Others just run their trucks when on calls.

When you're in park (and sometimes have to have the parking brake applied), typically an engine idler controller kicks in and keeps the rev's up for your air conditioning, generator, etc.


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## rescuepoppy (Nov 18, 2009)

When installing the box witj all of the different options that a client can get in them I would be afraid to try to guess what those switches are for. My advice would be to contact the manufacturer or the previous owner ( if known ) to see if they can help you.


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## MRE (Nov 19, 2009)

blackturbo said:


> did all these mccoy miller boxes come with a block heater stock?



Ours came with a block heater, we disconnected it though since the ambulance sits in a heated bay and  it was running up our electric bill quite a bit.


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## blackturbo (Nov 20, 2009)

*switches*

Yes i dont think Ill be driving it alot during the winter. Iam in the process of hooking up the emergency lights with yellow caution lighting. I cant figure out how the wig wag headlight flashers worked. I found a few flasher boxes, one in the rear with "A, B, C" terminals that work with the primary and secondary emergency lights, then I found another flasher under the dash, that only has A and B terminals, and the "intersection" switch turns that on regardless of primary or secondary switch position. Anyone know what all gets activated by the "intersection" switch?  Its pretty cool how they wired this stuff up. all ready for me to wire in my many gadgets .


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