Need to tap some power in the rear

[M1165A1]

I'm putting an air system in the M1165 and will be mounting the air storage tank in the vicinity of the rear cross member. I need a tap for 24V to run the auto drain on the tank and the pressure switch relay.

I took a look and can't find anything other than the main harness to the trailer plug, which I don't want to tap, and the lights.

If I want full time hot, then it seems my closest power pickup is maybe off the TCM or even off the batteries.

Have I missed anything here? Can anyone suggest something closer?

 

[Mogman]

The TCM operates on 12V.

 

[M1165A1]

The TCM operates on 12V.

Yes sorry should have been clearer - don't necessarily need 24 V as I can get versions of the air drain and relay in 12 or 24. I need hot power.

The compressor itself is sitting in the engine bay and is a 24V model. I plan to have switched relay power from the cabin, and a pressure relay in the tank for 120-150 PSI run on the unit. Still figuring this out as I only have the compressor and bracket and not much else yet. The compressor is taken from the field expendient refueling setup below:




More on this to come as I do the work in the next two weeks.

 

[Mogman]

Yes sorry should have been clearer - don't necessarily need 24 V as I can get versions of the air drain and relay in 12 or 24. I need hot power.

Others may have ideas, if it were me I would leave the TCM alone and grab power out of the battery box, fused of course.

 

[Mrgior31513]

Others may have ideas, if it were me I would leave the TCM alone and grab power out of the battery box, fused of course.

I just buy extension cords for projects like that and run new wire. They are all copper per U.S. codes, and the double insulation makes for easier install and more peace of mind. Figure out current draw, use adequate gauge for draw. I just picked up some 50ft 16ga extension cords on clearance for $6 at Home Depot to run some new wire for my trailer. When I get my engine swap done I'm going to grab some 12ga to rewire and rebulb it for 12v LED. Grabbing two different colored cables makes identifying wires easy enough, and wire is wire.

 

[Coug]

When I needed to run new power to the back for my trailer plug, I used a length of hard pex and ran the hot wire through it. The pex fit above the cross braces for the truck bed in the little gaps they have up there (just stick your head up under there and take a look)
Fused power from the battery is probably your best choice for any power back there.

 

[TOBASH]

I’ve read the title of this thread three times, and I still think it could have been written by Bob Guccione.

Tap power from batteries and use a relay. My strong suggestion.

 

[M1165A1]

So I think I will run from the battery bay. I'm not taking much power on the run to the pressure switch as it's the control side of the relay. Going to drop an in-line 10 amp fuse and forget about it. The compressor power will be getting a breaker and not a fuse in case. Compressor is continuous duty and I'm curious to see what it draws, I am going to measure as it fills up the tank during the install to see how many amps.

 

[Retiredwarhorses]

So I think I will run from the battery bay. I'm not taking much power on the run to the pressure switch as it's the control side of the relay. Going to drop an in-line 10 amp fuse and forget about it. The compressor power will be getting a breaker and not a fuse in case. Compressor is continuous duty and I'm curious to see what it draws, I am going to measure as it fills up the tank during the install to see how many amps.

the compressor should have its ratings on a decal or the mfg website…

 

[M1165A1]

The data tag is painted over on the compressor so I can’t read it there and I’m not sure which one of two models it is. It will either be 32 or 40 A.

 

[TOBASH]

Double that amperage when selecting wires and relays and switches.