Hello all, newbie here. Last year I bought an 86 F250 2wd with 460. I have been working on it over the winter. I am down to some wiring and relay questions and issues. First thing..one of the previous owners has wired up a push switch in order to start it. Turn key on push switch and it may or may not start? It has always cranked, takes a couple of tries to get it fired. I thought that maybe the wiring and relay under hood were suspect? Yesterday I purchased a new relay and relay connector from NAPA. Swapped in new relay and harness, now nothing. No cranking, no clicking, I do have dome lights, headlights, etc. After doing some searching here, I am not sure what I have? There are 2 relays under the hood by the brake master cylinder. One I assume is for the fuel? The other relay is where the P.O. has wired in the push switch. Wire from the fuse box into push switch, out of push switch into relay. I had thought it was the EEC relay, but now I am not sure? I have a Chilton's manual (which is junk as far as I am concerned). I have tried searching for wiring diagrams here. Can someone look at these pics and verify what I have? The ignition lock cylinder and also the ignition switch have already been replaced.

 

Welcome to FTE....
You can look at this, while others who have more knowledge see this post and chime in.

Gary's Garagemahal - Home

Also, how old is that NAPA module ?

 

Thanks for the link, I will do some reading there. Not sure how old the box is? I did buy a new one of those yesterday also. First want get it back to where it was, then on to the next thing.

 

The relay with the green socket screwed to the fender should be the fuel pump relay; that other one, no idea there... but the push-button-to-start functionality is exceedingly simple, all you need to do is apply power to the S terminal on the starter relay (normally done via a red/light-blue-stripe wire from the ignition switch to the clutch or NSS switch to the starter motor relay) to engage the starter motor, and how one goes about doing that is up to them.

 

You have a fuel pump relay, connected to a tank selector relay.
Default is the rear tank.

Bill Vose has this wiring diagram on his 'old school hotrodder' web page.

 

Here's a link to the wiring diagram. (And, oddly enough, this comes from Bill as well.) http://www.garysgaragemahal.com/elec...p-control.html

 

Thanks for all of the assistance. I wanted to give an update on this issue.


First, the relay in question was in fact for the fuel pump cut off relay. The other one that is attached to the fender is from the trailer lights harness. I discovered all of this using the EVTM manual pages posted on Gary's Garagemahal - Home link. I was able to download and print them out while working in the garage.


Second, I had found out that the previous owner had reversed 2 of the wires at the starter relay (solenoid). They had put the fusible link power wire for the fuel relay on the "S" terminal. They then wired the push button start to power back through the relay. Once I had that figured out, I removed the push button and wiring. After connecting the proper wire on the proper S terminal, it would engage the starter in the Run and Start position. I had then replaced the Ignition Control Module to cure that issue.


Every day working on this is an adventure!


Thanks again!
Ron

 

Ron - Well done! Thanks for letting us know.