Fuel shutoff solenoid wiring help

crewgirl

Inmate #28
Joined
Feb 16, 2007
Messages
4,913
Ok, so I've used the search function for 2 days now and I just want to make sure I'm doing this right. Well, at this point I want to make sure I buy all the right stuff and don't have to make a half a dozen trips to the store, but then I will want to do it right. I also don't want it to look all crappy and messy when I'm finished. Once I get all the stuff I need, and the proper instructions, I intend to do a pictorial write up about this for everyone's benefit.

Here's what I have/know I need....
Fuel shutoff solenoid off of an class 5 or 6 truck (thank you TSTC).... This is the slightly bigger one. I have the bracket that fits it. The solenoid has the wiring harness connector still attached.
I have been reading all about this and I know I need a 70 amp 3-prong relay and some of those lil blade terminal thingys to slip on the relay prongs.
I know I need an inline fusible link in 65 amps.
And I know I need a bunch of wire.

This is where I get all cross-eyed and confused. Let me just say that wiring in general confuses the hell out of me. In theory it should be simple, but I just can't wrap my brain around it and then I start second guessing myself.

So, the solenoid I have has 3 wires, red, black, and white. They all appear to be the same gauge wire. If what I've learned is correct, black is ground, white goes to the relay and red goes to a key on "hot" wire. I know at least one person grounded the black wire to the cylinder head, is there any reason why this is a bad idea? I saw where someone else spliced the red wire to the fuel heater circuit. Does that circuit have enough power to hold the solenoid open? Someone posted a wiring schematic from Dodge and it shows that the fuel heater circuit is 20 ga wire. The wire coming from the solenoid is much larger than that, which gauge wire should I use to route the red wire?
Now on to the relay wiring.... Does it HAVE to be 70 amp? This would be more helpful if I already had the relay and I'm sorry for not thinking of it before I began this post. How do I know which prong on the relay does what? I know there are numbers on the bottom next to the prongs, but the only relays I've messed with are 5 prong, so that's the only notes I have to look at. The wiring diagram posted by someone shows 14 ga wire going from the relay to the battery, 10 ga wire coming from the solenoid to the relay and 12 ga wire going to the (insert useless components here and replace with starter solenoid). Should I use that gauge of wires?
Ok, last couple questions. What's the difference between an inline fuse and a fusible link? Does it HAVE to be 65 amp? And finally, where the heck in this wiring mess does the fusible link go?
 
the black is ground. the white is pull and can be ran off the ignition wire on the starter. the red is the hold wire and is the one that needs to have a relay. i will put up this pic for reference only. http://www.the12volt.com/relays/relaydiagram25.html on the bottom of the relay there should be a similar diagram as in the picture. 87 will need a constant 12v source, 30 will be plugged into the red wire on your solenoid, 85 is to ground, and 86 will be connected to a 12v source that is constant while the vehicle is running. you should use the same gauge wire that is on the solenoid for the wire to the starter, the wire from the solenoid to the relay, and from the relay to the 12v constant source. the 12v acc wire can be a 14ga or whatever gauge wire is the normal wires( i am not good with actual sizes). if you run the white straight to the starter i would put a fuse inline with that, and the other fuse should be on the 12v constant source wire to the relay. i think that you only need a 30 amp fuse or the same size for the starter. if this doesnt help let me know and i will try to translate using thingamajig, whatchacalit, dewhicky, and other terms that might be easier to understand lol
 
Last edited:
The relay that is OEM on 12v's has only 3 prongs. Your telling me to use 4 prongs, and the picture has 5. Do the extra prongs not matter? What kinda relay did you use for your p pump 24v?
 
tyler did it before i bought the truck. on the 5 prong relays dont worry about the middle prong it has no use for what you are doing. anything i wire up that needs a relay i use the one i put in the pic as we have an over abundace of them at work and thats all we really use. yes you only use 4 out of the 5 prongs on the relay i showed you an example of. the one that is probably shown as oem that uses 3 wires is self-grounded by the case and it has the 12v source, then wire to solenoid, and the 12v acc wire to engage it.
 
This is so confusing! And now I've had someone put the idea in my head to wire the hold in circuit to a switch in the cab.....
 
Correction! On closer inspection of pictures online.... it appears to be a 4 prong relay
 
Why not use a cable? It scares some off but it is by far the most reliable and cheapest.
 
Mostly aesthetics. I want everything to look clean and "factory" as much as possible.
 
dont fret it too much. you'll get it figured out. your bus bar idea should help out some too.
 
My conversion is in a first gen, but I'd be happy to take a picture and detail where the wires go for the solenoid hookup.
 
I used a Standard auto RY116 relay
Napa 30A fuse holder


Shut off wires-Black wire to black wire on harness(C)
-White wire to Red wire on harness(B), then to #87 (Yellow wire) on relay
-Red wire to Small green wire on harness(A), then ran inside the truck through the firewall inside to #9 fuse



#85 (Blue wire) on relay went to starter
#86 (Lime green wire) went to ground (as seen in pics) and (C) on wiring harness went to this ground also
#30 (Red wire) went to fuse holder wire then other wire coming out of fuse holder goes to the positive on the battery
#87A middle(Orange wire) is not used

Probably still really confusing, but not sure if I can make it any easier.
 
Here are some pictures I took real quick.
 

Attachments

  • dtf 044.jpg
    dtf 044.jpg
    29.7 KB · Views: 0
  • dtf 045.jpg
    dtf 045.jpg
    72.2 KB · Views: 0
  • dtf 046.jpg
    dtf 046.jpg
    48 KB · Views: 0
  • dtf 047.jpg
    dtf 047.jpg
    55.4 KB · Views: 0
  • dtf 048.jpg
    dtf 048.jpg
    28.3 KB · Views: 0
  • dtf 049.jpg
    dtf 049.jpg
    28 KB · Views: 0
Have two trucks wired as such using same parts and both work great. Let me know if you have any questions.
 
Good thing i didn't post mine. It would probably have just confused the heck out of the issue.
 
Since I am on my phone, I can't figure out how to post a link to another thread. But, if you search 'shutoff' in the ppump 24v section, there is a thread with a wiring diagram from a book. I think posted by mech2161 or something. I followed that thread and wires mine in no time at all. Works flawless.
 
Back
Top