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Wiring 12 v air inflator to 7 pin trailer plug?

skon1212

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Dec 18, 2013
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I just bought a 2003 GMC 2500hd with air bags. The thing is, there is no on board compressor and the air inflatio shrader valve is next to the licence plate. I saw an old post where someone took a 12 volt portable inflator, cut off the cigarette lighter plug, and wired it to a 7 pin trailer plug. Bad thing is there are on instructions how he did it. Do simply just wire the hot and ground from the compressor wire to the hot and ground screws of the trailer plug or is there more to it? Thanks
 
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Jagmandave

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If you did it that way it would run all the time, wouldn't it?

At the very least you'd want an inline fuse and a switch. But is the 12V+ line heavy enough to carry the current draw of the compressor? Most cig lighters were protected with a 30 amp fuse.

On my (Euro style) connector one of the wires looked about 10 ga, if you have one that heavy it should work fine.
 
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skon1212

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It should only run when I plug it into the trailer receptacle shouldn't it? The inflator would not be plugged in all the time.
c38ba8a6.jpg

this is what I trying to do.
 

Jess

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Vancouver Island, BC Canada
I have a similar setup on a 2005 2500HD. The 12V trailer power is fused with a 40A fuse in the box under the hood. The Owners manual has the info on what/where if its not already installed. My fuse was in the bag with the trailer brake controller harness and other stuff I never used until we put a small camper on the truck. There should be lots of current to run a small compressor. I have a cheap one that uses the same set up as you have in the picture and its works fine to air up the bags or to do a tire inflate.
 
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skon1212

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Yeah me truck is wired for a trailer and already has the receptacle mounted to the truck. Just need the 7 pin plug and the inflator. I like the one in the pic but have no clue where to get one or what brand it is based on the pic.
 

Daves69

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Kernersville, N.C.
All you need is a 7 pin trailer connector and attach the wires to the number 1 ground and number 4 12v hot. The number 4 pin is usually protected with a 30amp fuse.

335572d1407682961t-converting-4-pin-trailer-7-pin-bargman-7-pin-connector.jpg
 
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skon1212

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Is there an easy way to tell which is hot and which is ground on the inflator? Still would like to know what brand inflator is in the pic.
 
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Daves69

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If you still have the original cig lighter plug the wire going to the center pin is hot. Look carefully at the wire sometimes there is a white tracer or ribbed on one of the wires.
 
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skon1212

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Haven't got the inflator yet but I will keep that in mind when I get it.
 

xyster101

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Upstate NY
Most cigarette lighters are fused with only 15amps. You will be fine. +1 to writing it up with both the trailer plug and cigarette plug.
 

c4cruiser

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Lacey WA
It sounds as though you are wanting to build a dedicated inflator just for the air bags. It might be a better idea to find a small 12V air pump (like this one from Harbor Freight)that uses a cig lighter plug and a cord that could be 10-12' long. That makes it useable for inflating tires too. Does your truck have "power ports" in addition to a cig lighter? Those outlets should have at least a 15A fuse protecting it.

I have had this Campbell-Hausfeld 12v inflator for a good 20 years now and it works great. It goes in my car trailer on race weekends and it simply plugs into the cig lighter port and easily reaches both sides of my car.
 

Falcon67

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Merkel, TX
Note that in some trucks - like my 2004 F150 - the +12 at the 7 way plug is not hot unless the engine is running.
 
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